RENATO TEIXEIRA SOUZA
UMA ANÁLISE DO PARTO PREMATURO TERAPÊUTICO NO
CONTEXTO DA PREMATURIDADE NO BRASIL
AN ANALYSIS OF PROVIDER-INITIATED PRETERM BIRTH
IN THE CONTEXT OF PREMATURITY IN BRAZIL
UNIVERSIDADE ESTADUAL DE CAMPINAS Faculdade de Ciências Médicas
RENATO TEIXEIRA SOUZA
UMA ANÁLISE DO PARTO PREMATURO TERAPÊUTICO NO
CONTEXTO DA PREMATURIDADE NO BRASIL
AN ANALYSIS OF PROVIDER-INITIATED PRETERM BIRTH IN
THE CONTEXT OF PREMATURITY IN BRAZIL
Dissertação de Mestrado apresentada à Pós-Graduação em Tocoginecologia, da Faculdade de Ciências Médicas da Universidade Estadual de Campinas para a obtenção do título de Mestre em Ciências da Saúde, área de concentração em Saúde Materna e Perinatal.
Master Dissertation presented to the Graduate Program on Obstetrics and Gynecology, School of Medical Sciences, State University of Campinas – UNICAMP to obtain the title of Master of Health Sciences, concentration area Maternal and Perinatal Health
ORIENTADOR: Prof. Dr. JOSÉ GUILHERME CECATTI
ESTE EXEMPLAR CORRESPONDE À VERSÃO FINAL DA DISSERTAÇÃO DEFENDIDA PELO ALUNO RENATO TEIXEIRA SOUZA
E ORIENTADA PELO Prof. Dr. JOSÉ GUILHERME CECATTI
BANCA EXAMINADORA DA DISSERTAÇÃO DE MESTRADO
Aluno: RENATO TEIXEIRA SOUZA
Orientador: Prof. Dr. JOSÉ GUILHERME CECATTI
Membros:
1.
2.
3.
Curso de Pós-Graduação em Tocoginecologia da Faculdade de Ciências Médicas da Universidade Estadual de Campinas
Resumo
Introdução: Mais de 15 milhões de bebês nascem prematuros anualmente no
mundo, sendo a prematuridade a maior causa de óbitos no período neonatal. A prematuridade terapêutica tem papel importante nesse contexto, pois se estima que 20 a 40% dos partos prematuros ocorrem por indicação dos provedores de assistência obstétrica. Dessa forma, a redução dos partos prematuros terapêuticos adquire cada vez mais importância para o controle da taxa de prematuridade e da morbimortalidade neonatais. O conhecimento dos fatores relacionados ao parto prematuro terapêutico é ponto fundamental para atingir essa redução. Objetivos: Avaliar a ocorrência do parto prematuro terapêutico e seus fatores associados na população do Estudo Multicêntrico de Investigação em Prematuridade (EMIP). Métodos: Análise secundária do EMIP, um estudo brasileiro de caso-controle aninhado a um corte transversal multicêntrico. O estudo ocorreu em 20 hospitais de referência em 3 regiões do Brasil de abril de 2011 a julho de 2012 e realizou a vigilância de 33.740 partos nesse período. O principal desfecho a ser avaliado é a ocorrência de parto prematuro terapêutico, definido como o parto que ocorreu antes de 37 semanas e que foi indicado pela equipe de assistência devido uma condição materna ou fetal. O grupo controle foi composto pelas mulheres com parto a termo. Os partos prematuros foram categorizados, conforme recomendações da Organização Mundial da Saúde, em prematuro extremo, muito prematuros e pretermo moderado Uma quarta categoria de idade gestacional, contemplando apenas os prematuros tardios, também foi analisada. Variáveis relacionadas a características sociodemográficas, pôndero-estaturais e de estilo de
presença de morbidade ou complicação durante a gravidez, parto ou puerpério foram avaliadas na análise de risco para parto prematuro terapêutico. Foi realizada uma análise bivariada para estimar o risco de parto prematuro terapêutico para cada e uma análise multivariada com regressão logística não condicional para obter os fatores independentemente associados ao desfecho. Resultados: O parto prematuro terapêutico foi responsável por 35,4% dos partos prematuros na amostra estudada. As síndromes hipertensivas, o descolamento prematuro de placenta e a diabetes foram as condições que mais frequentemente motivaram a resolução prematura da gravidez. A idade materna avançada, a hipertensão crônica, a obesidade e a gravidez múltipla foram as principais condições maternas relacionadas à ocorrência de parto prematuro terapêutico. Houve uma tentativa de tratamento da condição materna que motivou a resolução em mais de 50% dos casos e 74,5% das mulheres com parto entre 28 e 31 semanas receberam corticoterapia. A cesariana foi a via de parto mais frequente. A proporção de mortalidade neonatal, do Apgar do quinto minuto menor que sete e da admissão em unidade intensiva neonatal foi muito maior nos prematuros terapêuticos do que no termo, mesmo considerando os prematuros tardios. Conclusões: Os resultados do estudo corroboram com a crescente importância do parto prematuro terapêutico, devido sua prevalência e impacto nos resultados perinatais. A gravidez múltipla, idade materna avançada, a obesidade e a presença de morbidades pré-gestacionais são os fatores que requerem especial atenção nas estratégias de prevenção da prematuridade terapêutica.
Financiamentos: este estudo foi financiado pelo CNPq (Conselho Nacional de
Pesquisa) e FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo), processo FAPESP 2009/53245-5 (chamada AP.PPSUS-1).
Palavras-chave: Nascimento prematuro; Morbidade materna grave; Mortalidade
Abstract
Background: More than 15 million babies are born prematurely each year
worldwide and its the leading cause of deaths in the neonatal period. Provider-initiated preterm birth (piPTB) plays an important role in this context because it is estimated that 20-40% of preterm births occur by indication of obstetric care providers. Thus, the reduction in piPTB rate acquires more importance to decrease the rate of prematurity and neonatal morbidity and mortality. Knowledge of the factors related to piPTB is a key factor to achieve this reduction. Objectives: To evaluate the occurrence of provider-initiated preterm birth and the associated factors in the Multicenter Study on Preterm Birth in Brazil (EMIP) population. Methods: Secondary analysis of EMIP, a Brazilian multicenter cross-sectional study plus a nested case-control. The study took place in 20 referral hospitals in 3 regions of Brazil from April 2011 to March 2012 and conducted surveillance of 33,740 deliveries in this period. The primary outcome to be evaluated is the occurrence of provider-initiated preterm birth, defined as birth that occurred before 37 weeks and was medically indicated due to maternal or foetal condition. The control group was composed of women with term delivery. Preterm birth was categorized into extremely premature, very premature and moderate preterm, according to the World Health Organization. Another category that includes only the late preterm was also evaluated. Maternal, socio-demographic, obstetrical, prenatal care, delivery and postnatal characteristics were assessed as factors associated with piPTB. A bivariate analysis to estimate the risk for piPTB and a multivariate analysis using
piPTB was performed. Results: The therapeutic preterm labor accounted for 35.4% of premature births in the sample. Hypertensive disorders, placental abruption and diabetes were the main conditions related to pi-PTB indications. Advanced maternal age, chronic hypertension, obesity and multiple pregnancy were the main maternal conditions related to pi-PTB. There was an attempt to treat maternal condition that led to the resolution in over 50% of cases and 74.5% of women with birth between 28 and 31 weeks received corticosteroid therapy. Cesarean section was the most frequent mode of delivery. The proportion of neonatal mortality, Apgar score<7 at 5 minutes and NICU admission were much higher in provider-initiated preterm newborns than in term newborns, even considering the late preterms. Conclusions: The results of our study corroborate the increasing notability of provider-initiated preterm birth, due to its prevalence and impact on perinatal outcomes. Multiple pregnancies, advanced maternal age, obesity and the presence of pre-gestational morbidities are the main factors that require special attention in prematurity prevention strategies.
Fundings: the study was sponsored by CNPq (Brazilian National Research
Council) and FAPESP (Foundation for Support to Research of the State of Sao Paulo), process FAPESP 2009/53245-5 (Call AP.PPSUS-1).
Sumário
Resumo ... vii
Abstract ... ix
Símbolos, Siglas e Abreviaturas ... xvii
1. Introdução ... 1 2. Objetivos ... 11 2.1. Objetivo Geral ... 11 2.2. Objetivos Específicos ... 11 3. Publicação ... 13 4. Discussão Geral ... 45 5. Conclusões... 51 6. Referências Bibliográficas ... 53 7. Anexos ... 63
7.1. Anexo 1 – Centros participantes do EMIP ... 63
7.2. Anexo 2 – Publicação do projeto original do EMIP ... 64
7.3. Anexo 3 – Termos de Consentimento Livre e Esclarecido ... 71
7.4. Anexo 4 – Ficha de Coleta de Dados... 73
7.5. Anexo 5 – Manual do Entrevistador ... 84
7.6. Anexo 6 – Manual de Operações do OpenClinica® ... 129
Dedico este trabalho...
Aos meus pais, João Carlos e Maria do Carmo, que tanto fizeram para que seu filho pudesse seguir seus objetivos.
Às minhas irmãs, Regina e Rafaela, que sempre me deram suporte com tanto carinho.
À minha esposa, Maíra, amor da minha vida, minha companheira e porto seguro.
Agradecimentos
Aos meus pais, escolhidos não por acaso, pelo amor, carinho, respeito, dedicação e zelo que sempre tiveram com seus três filhos.
À minha irmã mais velha, que muito me ensinou e que trouxe outras duas pessoas muito importantes à minha vida: Luiz e Pietra.
À minha irmã mais nova, Rafaela, alma de artista, por sempre me receber com carinho e paciência.
À minha esposa, Maíra, por tantas alegrias que compartilhamos, pela ajuda e paciência nos momentos de dificuldade, pela companhia maravilhosa e constante aprendizado.
Aos meus padrinhos, Adelvacir e Nair, pelo carinho incondicional.
Aos meus avós, Jesuína e Tomas (in memoriam), Aparecida e Durvalino, pelos momentos maravilhosos da infância, pela paciência e cuidado com os netos. Aos meus familiares, Helena, Vanessa, Ana Beatriz, Rita, Batista e seus filhos pelo
apoio e carinho.
Aos meus sogros, Gustavo e Lilian, pelo carinho e suporte.
Aos meus amigos, pelos momentos de descontração, apoio e confidência.
Ao Prof. Dr. José Guilherme Cecatti, exemplar mestre, líder competente e generoso, pela confiança, orientação e pelos ensinamentos sempre com muita paciência. Pela inestimável oportunidade que me foi dada em poder aprender e trabalhar com um grupo que se encontra no estado da arte da pesquisa e ensino.
Ao Prof. Dr. Renato Passini Jr, pela iniciativa, inovação e competência nos estudos em prematuridade e pelo suporte na realização desse trabalho.
Aos Profs Dra. Mary Angela Parpinelli, Dr. Rodolfo Pacagnella, Dra. Maria Laura e Dra. Fernanda Surita, pela colaboração, ensinamentos e recepção carinhosa e paciente.
Aos outros pesquisadores e colaboradores do Estudo Multicêntrico de Investigação em Prematuridade no Brasil, que tornaram possível esse estudo.
Aos colegas da Red Room, Carla, Maria Júlia, Karayna e Nathália, pela amizade, carinho e ajuda, sempre acompanhados de boas energias e companheirismo. Pela conversa descontraída e pelos sérios momentos de reflexão. Pela agradável surpresa de conhecer pessoas especiais.
Aos Professores, funcionários e pacientes que colaboraram na minha formação nas Universidades Federais do Paraná e de São Paulo e na Universidade Estadual de Campinas.
Ao CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) e Fapesp (Fundação de Amparo à Pesquisa do Estado de São Paulo), pelo patrocínio financeiro deste estudo.
Às pacientes que participaram desse estudo, razão pela qual trabalhamos inquietamente.
Símbolos, Siglas e Abreviaturas
ACS – Antenatal corticosteroids
ANS – Agência Nacional de Saúde Suplementar BMI – Body mass index
CI – Confidence interval
CNPq – Conselho Nacional de Desenvolvimento Científico e
Tecnológico
CONEP – Conselho Nacional de Ética em Pesquisa DALY – Disability-adjusted life years
DATASUS – Departamento de informática do sistema único de saúde EMIP – Estudo Multicêntrico de Investigação em Prematuridade
no Brasil
EUA – Estados Unidos da América
Fapesp – Fundação de Amparo à Pesquisa do Estado de São Paulo FGR – Fetal growth restriction
HDI – Human Developmente Index
HELLP – Hemolysis, elevated liver enzimes, low plaquelets count HIV – Human immunodeficiency virus
IL – Illinois
IPD – Ischemic placental disease
Lilacs – Literatura Latino-americana e do Caribe em Ciências da
Saúde
MedLine – Medical Literature analysis and Retrieval System Online NICU – Neonatal intensive care unit
OMS – Organização Mundial da Saúde OR – Odds ratio
ORadj – Adjusted odds ratio
PHPN – Programa de Humanização no Pré-natal e Nascimento PHU – Primary health unit
piPTB – Provider-initiated preterm birth
pPROM – Preterm premature rupture of membranes PPT – Parto prematuro terapêutico
RPM – Ruptura prematura de membranas
SINASC – Sistema de Informações de Nascidos Vivos SISPRENATAL – Sistema de acompanhamento do programa de
humanização do pré-natal e nascimento
SPSS – Statistical Package for the Social Sciences sPTB – Spontaneous preterm birth
TX – Texas
Unicamp – Universidade Estadual de Campinas US – Ultrasound
USA – United States of America WHO – World Health Organization
YLD – Years of life with disabilities YLL – Years of life lost
1. Introdução
O parto prematuro é todo parto que acontece antes das 37 semanas de gestação segundo a Organização Mundial da Saúde – OMS (World Health Organization, 1977). Historicamente, os dados oficiais brasileiros relativos à taxa de prevalência de prematuridade são subestimados e não contemplam os diferentes subtipos de condições que determinam o parto prematuro (SILVEIRA
et al., 2009). O SINASC, Sistema de Informações sobre Nascidos Vivos, foi
implementado em 1990 e fornece informações epidemiológicas online referentes aos nascimentos notificados em todo território nacional desde 1994 (MINISTÉRIO DA SAÚDE, BRASIL; SILVEIRA et al., 2009). Segundo esses dados oficiais, a prevalência de prematuridade aumentou de 6,2% em 1994 para 12,4% em 2012, considerando apenas os casos em que o dado sobre a idade gestacional não foi ignorado (MINISTÉRIO DA SAÚDE, BRASIL).
Em 2008, Silveira et al, através de uma revisão nas bases de dados
MedLine e Lilacs, evidenciaram que os primeiros estudos de prevalência em
prematuridade no Brasil datam da década de 80 e são levantamentos institucionais ou loco-regionais (SILVEIRA et al., 2008). Esses estudos regionais e os dados do SINASC demonstram a tendência de aumento das
tendência mundial. A prevalência global estimada de nascimentos prematuros é de 15 milhões por ano, o que corresponde a 11,1% de todos os nascimentos (BLENCOWE et al., 2012).
As complicações provenientes do parto prematuro são a principal causa de morte neonatal, sendo também grande responsáveis pela morbidade a curto e longo prazos (BLENCOWE et al., 2013b; LAWN et al., 2005; LIU et al., 2012). O controle da prematuridade impacta, inclusive, no quarto objetivo de desenvolvimento do milênio, uma iniciativa das Nações Unidas que tem como meta a redução em dois terços da mortalidade de menores que 5 anos até 2015 (HOWSON et al., 2013; NOUR, 2012). Em torno de 40% das mortes de crianças abaixo de 5 anos acontecem no período neonatal e a prematuridade é a segunda maior causa de óbito nessa faixa etária (LIU et al., 2012). Considera-se, portanto, de extremo destaque o papel da redução da mortalidade por prematuridade para controlar a mortalidade neonatal e reduzir os índices de óbitos abaixo de 5 anos.
O aprimoramento das assistências obstétrica e neonatal, através do incremento dos tratamentos e medidas preventivas secundárias, terciárias e quaternárias, vem acarretando uma melhoria nas taxas de mortalidade e morbidade neonatais (HORBAR et al., 2012; LISONKOVA et al., 2011; SHAH et
al., 2012). Um estudo com mais de 350 mil lactentes prematuros extremos da
América do Norte demonstrou que, entre 2000 e 2009, a mortalidade e morbidade neonatais diminuíram em torno de 13% e 10%, respectivamente (HORBAR et al., 2012). Entretanto, é importante observar que o número
absoluto de prematuros e de casos de morbidade a curto e longo prazos seguem uma tendência de aumento, a despeito das melhorias de assistência e consequente melhoria relativa dos resultados neonatais. Além disso, ao possibilitar o aumento da sobrevida dos prematuros, sobretudo dos prematuros extremos, e a diminuição do limite da viabilidade, a melhoria da assistência obstétrica e neonatal vem determinando um aumento bruto do número de prematuros que poderão apresentar sequelas ou disfunções no futuro (MOORE
et al., 2012).
A OMS desenvolveu uma ferramenta capaz de estimar o impacto de uma doença ou condição, sendo um indicador mais abrangente do que a taxa bruta de mortalidade ou do que a prevalência (ARNESEN et al., 2004; MURRAY, 1994a; MURRAY et al., 1994b). O DALY (disability-adjusted life years) quantifica o número potencial de anos perdidos de vida saudável devido a uma determinada doença ou morbidade (World Health Organization, 2014). Ele é calculado através da soma de anos “potencialmente saudáveis” perdidos devido à morte precoce (anos de vida perdidos - years of life lost – YLL) ou devido aos anos vividos com incapacidade (anos vividos com incapacidade - years lived
with disabilities – YLD) em decorrência de uma determinada doença. Ao
ranquear o DALY de 291 agravos à saúde em 21 diferentes regiões do mundo, um estudo da OMS mostrou que a prematuridade é a oitava condição do
ranking, estando à frente de doenças pulmonares obstrutivas crônicas, acidente
automobilístico, depressão, tuberculose e diabetes (MURRAY et al., 2012). O impacto que uma doença exerce na potencial vida saudável da população pode
ser maior ou menor de acordo com a condição socioeconômica da região. A prematuridade mantem-se entre as dez primeiras com maior DALY no ranking nas regiões de baixa ou média renda, enquanto que nas regiões de alta renda (Europa, América do Norte, Leste Asiático e países desenvolvidos da Ásia), a prematuridade cai para além da vigésima posição (MURRAY et al., 2012).
Existem diferentes condições que determinam que o parto aconteça antes de 37 semanas de gestação: o trabalho de parto prematuro espontâneo (em inglês, spontaneous onset of preterm labour), a ruptura prematura de membranas (RPM; em inglês, prelabour premature rupture of membranes) ou o parto prematuro terapêutico (em inglês, provider-initiated preterm birth) (BLENCOWE et al., 2013a). O parto prematuro terapêutico (PPT) ocorre em razão de uma condição materna e/ou fetal que prejudica a evolução saudável e fisiológica da gestação e, mais do que isso, expõe ao risco a saúde materna ou fetal. Dessa forma, entende-se que o parto prematuro terapêutico torna-se, diante de uma situação de risco, a opção mais favorável e inevitável para salvaguardar a mãe e/ou o concepto.
Um estudo da OMS publicado em 2014 analisou a incidência de prematuridade em 29 países com diferentes Índices de Desenvolvimento Humano (IDH) (MORISAKI et al., 2014). Após avaliar quase 300 mil nascimentos, os autores identificaram que, quanto maior a renda do país, maior a proporção do PPT. Essa proporção variou de 20% a até 40%. Esse estudo também mostrou que o óbito fetal e a mortalidade neonatal foram mais prevalentes nos PPT em comparação com parto prematuro espontâneo. O
Global Survey, outro estudo da OMS realizado em 22 países de baixa e média renda, também identificou maior prevalência de óbitos neonatais nos prematuros de parto terapêutico (VOGEL et al., 2014a). Lisonkova et al. compararam a prevalência de PPT em 1995 e 2005 nos EUA, avaliando mais de 36 milhões de nascimentos (LISONKOVA et al., 2011). O estudo demonstrou que o principal determinante para o aumento da prevalência da prematuridade, que foi de 8,4% em 1995 para 10,4% em 2005, é o PPT. A proporção de PPT em relação aos nascimentos prematuros aumentou 68% nesse período; enquanto que os outros subtipos de prematuridade (parto prematuro espontâneo e RPM) mantiveram-se estáveis. Assim como no estudo de Morisaki et al., os autores identificaram que a mortalidade neonatal foi maior nos recém-nascidos cujos partos foram terapêuticos do que naqueles cujos partos foram espontâneos. Esses dados demonstram a crescente importância do PPT como um dos determinantes da prematuridade e da mortalidade neonatal.
O conhecimento dos fatores relacionados à prematuridade terapêutica é fundamental no processo de entendimento da sua ocorrência, do seu impacto e da sua prevenção (BECK et al., 2010; CHANG et al., 2013; LAWN et al., 2013; MORISAKI et al., 2014). O processo de decisão em “realizar” ou “não realizar” a resolução da gravidez é fundamental na determinação do parto prematuro terapêutico, momento no qual se decide se os riscos em dar seguimento à gravidez superam os riscos da prematuridade. O controle dos fatores
associados às complicações durante a gravidez e o diagnóstico acurado dessas complicações são essenciais para a redução das taxas de PPT.
Alguns estudos identificaram fatores significativamente associados à ocorrência de PPT como idade materna avançada, pré-eclâmpsia, anemia, diabetes, placenta prévia, macrossomia fetal, óbito fetal em gestação anterior, cesárea em gestação anterior e hipertensão crônica (JOSEPH et al., 2014; MORISAKI et al., 2014; TANDU-UMBA et al., 2014; VOGEL et al., 2014a). Esses fatores relacionam-se, em sua maioria, ou com a presença de morbidade materna ou com o antecedente obstétrico. O antecedente obstétrico de pré-eclâmpsia, por exemplo, é sabidamente de maior risco para novo quadro de pré-eclâmpsia e prematuridade na próxima gravidez (DUCKITT et al., 2005; MORISAKI et al., 2014). O sobrepeso e a obesidade são, por outro lado, condições significativamente associadas à morbidade materna crônica como hipertensão, diabetes e doença cardiovascular (WORLD HEALTH ORGANIZATION, 2000). Mais de 40% das mulheres brasileiras entre 35 e 44 anos têm sobrepeso e uma em cada dez, nessa faixa etária, é obesa (GIGANTE et al., 2009). Nessa faixa etária, ainda, estima-se que cerca de 20% tem hipertensão arterial e 3% tem diabetes (SCHMIDT et al., 2009). Tanto a idade materna avançada como o sobrepeso e obesidade, fatores de risco para hipertensão e diabetes, são condições de maior risco de morbidade materna e PPT (OLIVEIRA et al., 2013; TORLONI et al., 2009).
A diminuição da taxa de fecundidade e a gestação em idade cada vez mais avançada fazem já parte da nossa realidade (SANTOS et al., 2008), que
pode ser inserido num contexto mais amplo chamado de “transição obstétrica” (SOUZA, 2013). O processo de transição obstétrica é caracterizado pela diminuição das taxas de fecundidade, das taxas de mortalidade materna e pela diminuição da proporção de óbitos maternos por causas diretas em detrimento das causas indiretas (SOUZA et al., 2014). O Brasil segue com diminuição da taxa de fecundidade e da razão de mortalidade materna (BARROSb et al., 2010), entretanto, ainda se observa a predominância de óbitos por causas diretas, que são potencialmente evitáveis (BARROS et al., 2010b; MORSE et
al., 2011). Esse fato demonstra que ainda enfrentamos um grande problema de
assistência à saúde da mulher, apesar de avançar nos estágios de transição obstétrica e de ter, aparentemente, adequada estruturação das maternidades brasileiras (DE AZEVEDO BITTENCOURT et al., 2014). Esses problemas advêm, em parte, da dificuldade de prover assistência obstétrica de qualidade de forma descentralizada, da dificuldade do manejo de complicações maternas, piorando os resultados maternos e neonatais (PACAGNELLA et al., 2014), e da ineficácia em implementar na prática protocolos de tratamento e de prevenção de complicações obstétricas baseados em evidência (GIORDANO et al., 2014; PACAGNELLA et al., 2014).
Um dos relatórios do “Born Too Soon” (LAWN et al., 2013), uma ação internacional da OMS em prematuridade, enfatiza que é essencial prover adequada assistência pré-concepcional e promover saúde materna também nos âmbitos educacionais e nutricionais, realizar triagem de risco eficaz com adequado atendimento pré-natal para os diferentes níveis de risco, promover
educação aos profissionais responsáveis pela assistência a fim de diminuir as taxas de prematuridade. Para tanto, é prioritário conhecer mais a fundo os fatores de risco e desfechos relacionados aos subtipos de prematuridade e as limitações existentes no modelo de assistência à saúde da mulher. Portanto, as pesquisas em prematuridade que auxiliem a identificação das prioridades locais e ajudem a implementar estratégias de prevenção são urgentes e fundamentais.
Até 2011 não havia sido realizado no Brasil nenhum estudo abrangente com o objetivo de avaliar a prevalência dos subtipos de prematuridade, os fatores relacionados a esses subtipos ou seus desfechos perinatais. Diante da necessidade de entender a atual situação dos partos prematuros no Brasil, de conhecer a distribuição em diferentes regiões do país e de reunir informações acerca dos fatores associados aos subtipos de prematuridade, planejou-se o Estudo Multicêntrico de Investigação em Prematuridade no Brasil (EMIP) (LAJOS et al., 2014; PASSINI et al., 2010). Proposto e coordenado pela Universidade Estadual de Campinas, o estudo foi conduzido em 20 hospitais de referência obstétrica (Anexo 1 e 2) que fazem parte da Rede Brasileira de Estudos Saúde Reprodutiva e Perinatal, em 3 regiões do país. O estudo caso controle aninhado a um corte transversal realizou as coletas de dados de abril de 2011 a março de 2012, completando a vigilância de 33.740 partos. Todas as mulheres participantes concordaram em participar do estudo e assinaram o Termo de Consentimento Livre e Esclarecido (Anexo 3). Um rigoroso protocolo de coleta de dados e armazenamento foi implementado, utilizando-se um
formulário de coleta de dados contendo 306 variáveis (Anexo 4), que foram coletadas pelos pesquisadores locais após treinamento utilizando o manual do entrevistador (Anexo 5). Os dados coletados foram digitados em plataforma de dados online, cuja operacionalização foi padronizada pelo Manual do Operações do OpenClínica® (Anexo 6). O estudo teve aprovação do Comitê
Nacional de Ética em Pesquisa - CONEP (Anexo 7). Foi possível estabelecer um grande banco de dados dos partos prematuros (4.150 partos prematuros) e de uma amostra de 1.146 partos a termos (PASSINI et al., 2014). A prevalência global de prematuridade nos centros estudados no EMIP foi de 12,3%. Os dados coletados nesse estudo fornecem informações fundamentais para a concepção e implementação de estratégias e políticas públicas no tratamento e prevenção da prematuridade no Brasil.
A análise dos dados do EMIP com enfoque nos partos prematuros terapêuticos pode trazer informações valiosas para o entendimento do cenário da prematuridade terapêutica e de seus fatores associados no Brasil. A avaliação das condições que levam à indicação do parto prematuro terapêutico, dos resultados perinatais e dos fatores que agregam maior risco para essa prematuridade são inovadoras no nosso meio e poderão ajudar a encontrar o caminho para melhorar os desfechos maternos e neonatais.
2. Objetivos
2.1. Objetivo Geral
Analisar a ocorrência de parto prematuro terapêutico no Brasil através dos dados do Estudo Multicêntrico de Investigação em Prematuridade (EMIP) e seus fatores associados comparativamente a uma amostra de partos a termo.
2.2. Objetivos Específicos
Estimar a proporção de parto prematuro terapêutico dentre os prematuros da população estudada.
Analisar as características da assistência empregada aos casos de prematuridade terapêutica.
Analisar os resultados perinatais de prematuros terapêuticos.
Analisar os principais fatores associados ao parto prematuro terapêutico em uma rede de hospitais no Brasil.
3. Publicação
Artigo – The burden of provider-initiated preterm births and associated
factors: evidence from the Brazilian Multicenter Study on Preterm Birth (EMIP)
Souza RT, Cecatti JG, Passini Jr R, Tedesco RP, Lajos GJ, Nomura
ML, Rehder PM, Dias TZ, Haddad SM, Pacagnella RR and Costa ML, for the Brazilian Multicenter Study on Preterm Birth study group. Bull World Health Organ 2015 (Submitted).
RESEARCH
The burden of provider-initiated preterm birth and associated factors:
evidence from the Brazilian Multicenter Study on Preterm Birth (EMIP)
Renato T Souza, a Jose G Cecatti, a Renato Passini Jr, a Ricardo P Tedesco, a,b Giuliane J Lajos, a Marcelo L Nomura, a Patricia M Rehder, a Tabata Z Dias, a Samira M Haddad, a Rodolfo R Pacagnella, a Maria L Costa, a for the Brazilian Multicenter Study on Preterm Birth study group
a Department of Obstetrics and Gynecology, University of Campinas (UNICAMP)
School of Medical Sciences, Campinas, SP, Brazil
b Department of Obstetrics and Gynecology, Jundiaí Medical School, Jundiaí, SP, Brazil
Correspondence: JG Cecatti DO&G University of Campinas R. Alexander Fleming, 101 Campinas, SP, 13083-881 Brazil E-mail: cecatti@unicamp.br
Abstract
Objectives: To assess the proportion of provider-initiated (pi-PTB) among preterm
births in Brazil and identify associated factors.
Methods: This is an analysis of a multicenter cross-sectional study conducted in 20
referral obstetric hospitals in Brazil, focusing on pi-PTB. Pi-PTB was defined by caregiver indication, regardless of the reason for indication. The current approach corresponds to a nested case-control design where maternal, sociodemographic, obstetric, prenatal care, delivery and postnatal characteristics were assessed as possible factors associated with pi-PTB, compared to term births. The adjusted OR and 95%CI were used in bivariate and multiple regression analysis.
Findings: The overall prevalence of preterm births was 12.3%. Of these, approximately
one-third of cases were initiated by the provider. Hypertensive disorders, placental abruption and diabetes were the main maternal conditions leading to pi-PTB. Caesarean section was the most common mode of delivery. Chronic hypertension (OR 7.47; 95%CI 4.02–13.88), preeclampsia/eclampsia/HELLP syndrome (OR 15.35; 6.57–35.88), multiple pregnancy (OR 12.49; 4.86–32.05) and chronic diabetes (OR 5.24; 2.68–10.25) were the most significant factors independently associated with pi-PTB.
Conclusions: pi-PTB is responsible for about one-third of all preterm births, requiring
special attention, since it has risen in the last decades. The decision-making process relative to the choice of provider-initiated birth is complex and many factors should be elucidated to improve strategies for its prevention, including evidence-based guidelines on proper management of the corresponding clinical conditions.
Funding: Brazilian CNPq and Fapesp played no other role in the study.
Keywords: preterm birth, provider-initiated preterm birth, risk factors, multicentre
Introduction
The World Health Organization (WHO) estimates that the worldwide incidence of preterm births is 15 million annually, accounting for 11.1% of all births.1 More recently, the prevalence of preterm births in Brazil has been estimated to range from 9.9% 1 to 12.3%.2 The main conditions leading to preterm birth are spontaneous preterm labor, preterm premature rupture of membranes (pPROM) or provider-initiated (medically indicated) delivery, due to maternal or fetal indications. 3–5 Contributing factor vary widely among different regions or countries. 6,7 There is some indication that the substantial rise in preterm births observed during the last few decades may be explained by growing pi-PTB rates. 3
Multiple risk factors play a role in such distinct rates. Pi-PTB is recurrently associated with either maternal pathological conditions (severe preeclampsia, eclampsia, placental abruption, placenta previa, and other severe maternal clinical conditions); or fetal conditions (fetal growth restriction, fetal distress or even fetal malformations). In addition, some maternal characteristics and morbidities including age, race/ethnicity, body mass index, assisted reproductive procedures, hypertension, diabetes and others are closely linked to a higher pi-PTB risk. 4,7–10
The WHO Multicountry Survey analysed more than 300,000 births, concluding that maternal age >35, nulliparity, previous C-section, anaemia, malaria/dengue, chronic hypertension and preeclampsia/eclampsia were maternal conditions associated with pi-PTB. Furthermore, stillbirth and early neonatal death rates were higher in pi-PTB than in spontaneous preterm births (sPTB). 6
Preterm birth is the current leading cause of neonatal mortality. It is also responsible for more than half of long-term neonatal morbidities. 11-13 However, death rates resulting from prematurity have not shown the same reduction as global neonatal mortality rates in recent decades. 11 A study from 192 countries showed that the lower the neonatal mortality rate, the higher the importance of prematurity in the etiology of neonatal death. Despite the decrease of neonatal mortality, the preterm component remains static. In some cases, it is even higher and most likely attributed to pi-PTB.14
A decrease in pi-PTB is essential to reduce global prematurity and its resultant neonatal morbidity and mortality, 4,13 particularly in middle-, and very
high-income countries 6, as part of effective preventive strategies for the preconception or
postconceptional periods. 15–17 It is then fundamental to investigate the underlying
conditions related to pi-PTB in different backgrounds. 15,18 Therefore, we intend to identify the prevalence and main factors associated with pi-PTB, as well as corresponding perinatal outcomes in the Brazilian Multicentre Study of Preterm Birth (EMIP). 19,20
Methods
Analysis of the Brazilian Multicentre Study on Preterm Birth (EMIP) that took place in 20 referral obstetric hospitals located in the three most populated regions of Brazil. Methodological details of this study were published elsewhere. 19–21 Briefly, this cross-sectional study carried out surveillance of 33,740 deliveries from April 2011 to July 2012. A dataset of all preterm deliveries and preterm infants was established, implementing a nested case-control component to compare preterm births with term-birth sample. A term term-birth immediately after a preterm term-birth was included as a proxy for a randomly selected control group, until reaching the previously estimated sample size. Sample calculation for the whole study was based on the Brazilian preterm birth prevalence of 6.5% in 2006 and at least 1054 subjects per group for the case-control component. 2,19,22
During the data collection period, each participating centre monitored preterm births continuously to identify women eligible for the study. Once identified, women were invited to participate. After receiving explanations, agreeing to participate and signing a consent term, these women were enrolled. Information was collected through three sources: postpartum interview using a structured questionnaire and medical chart review. Neonatal data was collected up to sixty days after birth.
The main outcome was pi-PTB, defined as childbirth occurring at less than 37 weeks, medically indicated for maternal/fetal compromise or both; or term birth, childbirth at or after 37 weeks. Preterm birth were classified as extremely preterm (before 28 completed weeks), very preterm (from 28 to 31 completed weeks) and moderately preterm (from 32 to 36 completed weeks), according to World Health
(from 34 to 36 completed weeks) was reported. 23 Other secondary outcomes were
admission to neonatal intensive care unit (NICU); Apgar score < 7 at 5 minutes; low birth weight (<2500g); and neonatal mortality.
Variables assessed as potential predictors of pi-PTB were related to sociodemographic characteristics, working status, maternal weight assessment, reproductive and obstetric history, prenatal care (including adequate number of prenatal care visits for gestational age, previously defined by the Brazilian Ministry of Health 24), lifestyle and habits, data on short cervix (clinical history or cervical length < 25 mm measured between 14 to 24 weeks by vaginal ultrasound scan), suspected cervical insufficiency (clinical or ultrasound signs), cerclage during pregnancy, uterine fibroid, vaginal bleeding, oligohydramnios or polyhydramnios, fetal malformation, fetal growth restriction, multiple pregnancy, features of maternal and fetal care, and maternal and/or fetal indication for delivery.
Several procedures were adopted to ensure high-quality data and reliable information, including preparatory meetings, use of a detailed manual of operation, site visits, technical visits to participating centers, closely monitored data collection and data entry, concurrent query management, inconsistency checks, and database correction. 20
The study was approved by the National Research Ethics Council (CONEP) and the Institutional Review Board of each centre. All participants signed an informed consent term before study entry and confidentiality of patient identity was ensured. The study complied with the Declaration of Helsinki, following Brazilian National Health Council Resolution 196/96.
Statistical Analysis
Pi-PTB prevalence was estimated among all preterm births occurring in participating centres during the data collection period. Estimation was based on geographical region, gestational age and delivery indications. Delivery indications, maternal and neonatal outcomes were distributed according to gestational age, and evaluated by χ2 tests.
Bivariate analyses were conducted to estimate pi-PTB risk, using the Odds Ratio (OR) with 95% confidence intervals (CI) for each predictor, adjusting for clustering effect design. To identify factors independently associated with pi-PTB, a multivariate analysis using non-conditional multiple logistic regression was performed, reporting the
estimated adjusted ORadj with a 95% CI. Backward stepwise regression was performed
including all variables in the logistic regression model. Each centre was considered a cluster. Low intracluster correlation coefficients for variables were considered appropriate, since centers heterogeneity strengthen sample representation. 21
Statistical analysis was carried out using SPSS version 20.0 (SPSS, Chicago, IL, USA) and Stata version 7.0 (StataCorp, College Station, TX, USA). A p-value <0.05 was considered significant.
Results
EMIP carried out surveillance of 33,740 births in 20 participating centres, identifying 1,468 pi-PTBs, and selecting a sample of 1,146 term births (Figure 1). The global prevalence of preterm birth was 12.3%. The proportion of pi-PTB among all preterm births was 35.4%, ranging from 34.7% in the Southeast to 39.6% in the South of Brazil. The Southeast region accounted for the majority of the pi-PTB (54.1%), while only 14% occurred in the South in this sample (Table 1). Multiple pregnancies occurred in 7.7% of pi-PTB, representing 25.9% of all preterm multiple births identified. More than three-quarters (76.7%) of births occurred between 32 and 36 weeks, while the lowest proportion occurred in pregnancies less than 28 weeks (6.9%). The late pi-PTB (34-36 weeks) corresponded to almost 60% of them.
Exclusive maternal condition was the main indication for delivery in 45.9% of pi-PTB. Hypertensive disorders (preeclampsia – 58.2%, chronic hypertension – 15.3%, gestational hypertension – 12.9%, and HELPP syndrome – 9.4%) were the most common indications, regardless of gestational age (Tables 1 and 2). HELLP syndrome and placental abruption occurred more frequently before 32 weeks (Table 2). Fetal distress and fetal growth restriction (FGR) were the most important fetal indications in all gestational ages (Table 2). Major fetal surveillance methods used were Doppler ultrasound and cardiotocography. Fetal movement counting was rarely employed. Table 2 also shows that only 58.2% of women with pregnancies interrupted at less than 28 weeks received antenatal corticosteroids (ACS). However, almost three-quarters of women between 28-31 weeks received corticosteroids for fetal lung maturation at least
Table 3 shows that the proportion of vaginal delivery was only 11.4% in pi-PTB and 56.7% in term births.The prevalence of vaginal delivery before 28 weeks doubled in comparison to other gestational ages, although it was only 26.7%. Neonatal outcomes in preterm groups were much worse than in the term group, even comparing the 34-36 week group to the term group (Table 3). Neonatal death before dischargewas more than 200 times higher in the subgroup under 28 weeks and 54 times higher in the 28-31 week subgroup than in the term group. The difference is still significant between the 34-36 week group and the term group (6.3-fold).
Tests supporting the decision to deliver and obstetric care characteristics according to indication for pregnancy interruption among pi-PTB are shown in Table 4. Doppler ultrasound was the most frequently used test in fetal or maternal/fetal indications (43.8% and 46.4%, respectively). When maternal compromise indicated pregnancy interruption, haematological (27.7%) and liver function panel (23.5%) were the most common tests ordered. Attempts to treat the clinical condition causing pi-PTB and ACS use were lower in fetal (29.2% and 32.8%, respectively) than in maternal indication (66.9% and 43.3%, respectively) or maternal and fetal (68.5% and 49.6%, respectively). However, no difference was identified in treatment duration between both conditions (Table 2 and 4).
Case assessment of estimated pi-PTB risk showed that maternal age ≤ 19 had a 28% lower risk, while > 12 years of schooling had a 64% higher risk, and maternal age ≥ 35 had a 99% higher risk. Furthermore, having children aged 5 years or younger exerted a protective effect. On the other hand, some obstetric conditions were associated with increased pi-PTB risk, e.g. previous C-section, inter-pregnancy interval ≤ 12 months, previous preterm birth and previous newborn under 2500g (Table 5 and 6).
Table 7 shows conditions associated with increased pi-PTB risk: fetal growth restriction (12-fold), multiple pregnancy (9-fold), preeclampsia/eclampsia/HELLP (9-fold), oligohydramnios (7-fold), fetal malformation (5-fold), chronic hypertension (5-fold), chronic diabetes (4-fold), systemic lupus erythematosus (5-fold), prenatal care not only in primary health unit (2-fold), polyhydramnios (2-fold), gestational hypertension (2-fold), gestational diabetes (2-fold), inadequate number of prenatal care visits (2-fold), obesity (1.8-fold), smoking during first and second trimester (1.8-fold), overweight (1.4-fold), vaginal bleeding
(1.4-fold) and weight gain ≤7kg (1.3-fold). Women who gained more than 12kg during pregnancy and initial BMI < 18.5kg/m2 were at lower risk for pi-PTB.
Finally, results of multivariate analysis are in Table 8. Preeclampsia/eclampsia/HELLP (ORadj 15.35; 95%CI 6.57–35.88) or multiple pregnancy
(ORadj 12.49; 4.56–32.05) were the strongest risk factors for pi-PTB. Other hypertensive
disorders (chronic hypertension and gestational hypertension), maternal morbidities (chronic diabetes, cardiac disease and systemic lupus erythematosus) and vaginal bleeding during pregnancy also showed higher risks for pi-PTB. The higher the maternal age or initial BMI, the higher the pi-PTB risk, whereas the higher the final BMI, the lower the risk for pi-PTB. Non-white skin colour was identified as factor associated with a lower pi-PTB risk.
Discussion
The EMIP study corroborates a recent upward trend in national and global preterm rates.
2,4 Previous studies have shown that pi-PTB is responsible for almost one-third of
preterm births in Latin America. In higher-income populations with better access to health care, pi-PTB has increased, remaining the fastest growing determinant of preterm birth in recent decades. 3,6,7,25 Consistent recognition of pregnancy complications and maternal morbidities using screening protocols could partially justify the higher pi-PTB rates in middle and high-income settings.
Pi-PTB is not only the result of provider preference when faced with either pregnancy complications or prematurity consequences. It can also be a life-saving decision for both the mother and fetus. Pregnancy interruption seems more reasonable in the “near term” (34-36 weeks) group. Almost 60% of all pi-PTB currently occurs in this gestational age group. Nevertheless, this decision-making emblematic scenario in the late preterm group requires careful attention, since previous reports have described that more than 50% of late pi-PTB indications were not evidence-based. 26 In our data, less
than 50% of pi-PTB due to fetal compromise had the support of Doppler ultrasound or cardiotocography. Only about one-quarter of pi-PTB due to maternal conditions were supported by maternal exams/tests, highlighting the importance of evidence-based decisions.
Obesity and advanced maternal age are factors related to a higher risk of preeclampsia, diabetes, chronic hypertension and other pregnancy complications or chronic diseases, and also resultant pi-PTB. 27–31 The higher the BMI before pregnancy, the higher the pi-PTB risk. 30–33 In contrast, underweight women before pregnancy and maternal age < 19 were related to a higher sPTB risk for the EMIP population, 2 but not for pi-PTB. Advanced maternal age also increases the need for assisted fertility treatments, elevating the prevalence of multiple pregnancy, an important condition for both pi-PTB and sPTB.4 Brazilian women conceive at increasingly older ages. In overweight or obese women, the scenario is unfavourable for a healthy pregnancy. 34,35 Preconception care package including nutritional, educational and family planning programs should be considered to prevent this situation. 18
Management of the clinical condition leading to pregnancy interruption was performed in more than 50% of cases. The most commonly treated or prevented maternal conditions were decompensated hypertension and diabetes. 36,37 However, the prevention of complications exclusively related to fetal conditions seems limited. 38,39
Caesarean section was significantly more frequent in pi-PTB than in term births, reaching 91.3% between 28 and 31 weeks. This potentially life-saving therapeutic mode of delivery increases maternal and neonatal morbidity and mortality. 40 Some women
and/or fetuses are already at risk when a pi-PTB is indicated, therefore additional risk factors should be only considered when an evidence-based indication exists.
In the current study, more than half of pi-PTB occurred in conditions defined as ischemic placental disease (IPD), including preeclampsia, eclampsia, HELLP syndrome, fetal growth restriction, chronic hypertension and placental abruption. IPD culminates in uteroplacental underperfusion, a phenomenon mediated by many biochemical angiogenic factors and autoimmune response regulators that are associated with its pathophysiology. 41 Further studies of IPD could help prevent this condition. 42
It is also important to compare factors associated with sPTB to those related to pi-PTB in order to identify interrelationships between such complex outcomes. The population at higher risk for each condition, neonatal outcomes and risk factors may vary depending on the main determinant (spontaneous onset, pPROM or pi-PTB). 4,6,7,25 Previous analyses of EMIP showed that maternal age and years of schooling were the
main factors associated with sPTB. 2 It was demonstrated that older white women, with
higher schooling had more pi-PTB. This is not an indubitable phenotypic risk. A high-risk group could be at increased high-risk for pi-PTB, and receive more specialized care. 6 These women have more access to prenatal care, adhering strictly to medical appointments. Owing to higher education, they have a better self-perception of risk, undergoing more fertility treatments due to advanced age, resulting in a higher proportion of multiple births.
Some possible limitations of this study exist. First, the evaluation of antenatal corticosteroid use according to WHO gestational age subcategories could be misinterpreted. The percentage of corticosteroid use was probably underestimated in women with pi-PTB below 28 weeks because there is no evidence-based indication below 24 weeks. 43 In fact, at that gestational week none of the women received ACS (n=11, data not shown). Additionally, the moderate to late preterm subcategory (32-36 weeks) includes gestational age when ACS use is not recommended (34-36), underestimating its use. However, ACS was used in almost three-quarters of the 28-31 week group. Although this is not yet an ideal rate for a pi-PTB, it was significantly higher than ACS provided to one-third of preterm births in Brazil, as reported by the WHO Multicountry Survey. 44 It is worth mentioning that some pi-PTBs had urgent
indication, with insufficient time for a complete ACS regimen. Second, although the study was conducted in 20 referral facilities throughout Brazil, definitely this is not a population study. The higher prevalence of high-risk pregnant women in participating centres weakened sample representativeness for the entire Brazilian population. Finally, weight gain during pregnancy would be better assessed if the weight gain pattern had been used separately by different BMI categories, since suitability of weight gain depends on the initial maternal BMI. 45 This point is planned to be the focus for a further in depth secondary analysis, as is also the case for fetal malformations, multiple pregnancies and some other very specific conditions.
Neonatal outcomes in pi-PTB are dependent on some antenatal factors, including gestational age, multiple pregnancies, ACS use, maternal complications (preeclampsia, HELLP syndrome, chronic hypertension, diabetes, infection, etc.) and fetal
the risk of early neonatal death in sPTB infants was shown to be lower than in pi-PTB infants. 46. Maternal and fetal compromise before delivery may determine worse
outcomes. The higher prevalence (6-fold) of late preterm neonatal death compared to term neonates indicate that an alternative approach for decision-making strategies and high-quality neonatal support for this group should be considered. 26
The main strengths of EMIP study were the high number of cases, and validation and crosschecking rules of data collection for more than 300 variables, allowing analysis of the Brazilian preterm background with high-quality reliable data. To the best of our knowledge, there is no other official data on determinants of preterm birth in Brazil with such a comprehensive approach. Therefore, the EMIP database is extremely important to assess conditions related to pi-PTB, at least for the Brazilian population. Recognition of conditions related to pi-PTB, evaluation of perinatal outcomes, reassessment of correlated clinical practices and management protocols are the key to making progress in primary, secondary and tertiary preventions of preterm birth. 15,17,18
Competing interests:
The authors declare no conflicts of interests.
Acknowledgements
The authors acknowledge CNPq (Brazilian National Research Council) and FAPESP (Foundation for Support to Research of the State of Sao Paulo) for financial sponsorship of the study, Process Fapesp 2009/53245-5 (Call AP.PPSUS-1). These organizations did not participate in the study proposal, implementation or interpretation of results.
The Brazilian Multicentre Study on Preterm Birth study group: Sergio T Marba,
Ruth Guinsburg, Francisco E Martinez, Vilma Zotarelli, Lucio T Gurgel, Francisco E Feitosa, George N Chaves, Ana M Porto,Isabela C Coutinho, Antonio C Barbosa Lima, Elias F Melo Jr, Débora F Leite, Melania M Amorim, Adriana SO Melo, Fabiana O Melo, Marília G Martins, Marynea V Nunes, Cláudio S Paiva,Moises D Lima, Djacyr M Freire, Edson G Tristão, Denis J Nascimento, Carlos A Menezes, Marcelo Aquino, Janete Vettorazzi, Cintia E Senger, Augusta MB Assumpção, Marcela AF Guedes, Maria EL Moreira, Vera T
Borges, Nelson L Maia Filho, Jacinta P Mathias, Eduardo Souza, Ana CP Zamarian, Silvana M Quintana, Patrícia PS Melli, Fátima A Lotufo, Kaliane Uzilin, Elvira A Zanette, Carla B Andreucci, Tenilson A Oliveira, Laércio R Oliveira, Marcos A N Santos, Nelson Sass, Mirian RF Silveira, Pedro R Coutinho, Luciana Siqueira.
What was already known of the topic concerned
Provider-initiated preterm birth is gaining more importance in recent decades, since major efforts to prevent preterm births have achieved limited results. The proportion of pi-PTB has increased with decreasing neonatal mortality and increasing human development index. Some conditions, including advanced maternal age, preeclampsia, previous caesarean section, placenta previa and hypertension were identified as risk factors for pi-PTB. There is no previous comprehensive study specifically exploring this preterm birth subtype and its associated factors. In-depth knowledge of underlying conditions associated with PTB is essential to improve preventive strategies for pi-PTB and consequently preterm birth, that no longer occur only in high-income, but also in middle-income settings.
What new knowledge the manuscript contributes
Identifying factors associated with pi-PTB contributes to strategies for preterm birth prevention, including preconception care package, high-risk pregnancy screening, and human and material resources required in obstetric and neonatal care facilities. The proportion of pi-PTB is also already high among all preterm births in a middle-income country, as probably occurs in other similar settings. The need for future larger studies is highlighted to build a real profile of these conditions and understand how to implement primary and secondary pi-PTB prevention.
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Figure 1. Flow chart of cases in the Brazilian Multicentre Study on Preterm Birth Sample of term births Total births 33,740 Controls 1,146 Preterm births 4,150 12.3% Spontaneous onset 1,491 35.9% pPROM 1,191 28.7% Provider-Initiated 1,468 35.4%
