Differences in risk factors for incident and recurrent preterm birth: a population-based linkage of 3.5 million births from the CIDACS birth cohort

Abstract

Background Preterm birth (PTB) is a syndrome resulting from a complex list of underlying causes and factors, and whether these risk factors differ in the context of prior PTB history is less understood. The aim of this study was to explore whether PTB risk factors in a second pregnancy were different in women with versus without previous PTB. Methods We conducted a population-based cohort study using data from the birth cohort of the Center for Data and Knowledge Integration for Health (CIDACS) for the period 2001 to 2015. We used longitudinal transition models with multivariate logistic regression to investigate whether risk factors varied between incident and recurrent PTB. Results A total of 3,528,050 live births from 1,764,025 multiparous women were analyzed. We identified different risk factors (Pdifference <0.05) between incident and recurrent PTB. The following were associated with an increased chance for PTB incidence, but not recurrent: household overcrowding (OR 1.09), maternal race/ethnicity [(Black/mixed—OR 1.04) and (indigenous—OR 1.34)], young maternal age (14 to 19 years—OR 1.16), and cesarean delivery (OR 1.09). The following were associated with both incident and recurrent PTB, respectively: single marital status (OR 0.85 vs 0.90), reduced number of prenatal visits [(no visit—OR 2.56 vs OR 2.16) and (1 to 3 visits—OR 2.44 vs OR 2.24)], short interbirth interval [(12 to 23 months—OR 1.04 vs OR 1.22) and (<12 months, OR 1.89, 95 vs OR 2.58)], and advanced maternal age (35–49 years—OR 1.42 vs OR 1.45). For most risk factors, the point estimates were higher for incident PTB than recurrent PTB. Conclusions The risk factors for PTB in the second pregnancy differed according to women’s first pregnancy PTB status. The findings give the basis for the development of specific prevention strategies for PTB in a subsequent pregnancy.

Recurrent preterm delivery following twin versus singleton preterm delivery: A retrospective cohort

“…Multiple etiologies are suspected to be involved in PTD recurrence, and it is likely that persistent factors, such as genetics and environmental exposures, contribute to the risk for PTD recurrence. 21 The findings in this study support the benign nature of PTD in twin gestations as a risk factor for subsequent PTD compared with singleton gestation. Length of pregnancy is shorter in twin pregnancies, possibly due to the over-distension of the uterus which affects birth timing.…”

“…Multiple etiologies are suspected to be involved in PTD recurrence, and it is likely that persistent factors, such as genetics and environmental exposures, contribute to the risk for PTD recurrence 21 …”

“…However, as this is a retrospective study, some limitations are nested in this design and the use of data not created or collected to answer a specific research question, including possible unmeasured confounding, such as information on maternal diet and changes in body mass index between pregnancies, as well as environmental exposures, which have been shown to be associated with PTD recurrence. 21 Another limitation is the unexpected, relatively low incidence of progesterone treatment in the subsequent pregnancies. Possible explanations for this may be the wide range of years included in the study, including before progesterone treatment was recommended, the fact that approximately 60% of the study members were Bedouin Arab women, who are less likely to confer with the pregnancy follow-up program, 27 and there is a possibility that some medications were not identified in our database, leading to a misclassification of this documentation.…”

Maternal factors during pregnancy influencing maternal, fetal, and childhood outcomes

“…To address this question, the authors examined a large retrospective dataset from Brazil representing 1.7 million births [ 13 ]. They focused on women who had a preterm birth in their second pregnancy and split them according to whether their first pregnancy was delivered at full term (> 37 weeks gestation, “incident preterm birth” cohort) or they previously had a preterm birth (< 37 weeks gestation, “recurrent preterm birth” cohort).…”

Sociodemographic and gestational factors of adolescent mothers associated with prematurity

“…Ainda que os resultados deste estudo tenham demonstrado associação da prematuridade com o número de consultas pré-natal adequado, considerando-se as possíveis justificativas apresentadas, recomenda-se veementemente a realização da assistência pré-natal qualificada para prevenção e detecção de condições de risco à saúde da mãe e do bebê (16) . O acompanhamento pré-natal efetivo favorece o reconhecimento de condições clínicas desfavoráveis ao seguimento da gestação, possibilitando diagnóstico e tratamento das complicações da gravidez em momento oportuno, além de auxiliar na redução dos fatores de risco comportamentais associados à prematuridade (26)(27) .…”