Risks of preterm birth among non‐Hispanic black and non‐Hispanic white women: Effect modification by maternal age

Abstract

Background Preterm birth (PTB) disproportionately affects African American compared with Caucasian women, although reasons for this disparity remain unclear. Some suggest that a differential effect of maternal age by race/ethnicity, especially at older maternal ages, may explain disparities. Objective To determine whether the relationship between maternal age and preterm birth varies by race/ethnicity among primiparae non‐Hispanic blacks (NHB) and non‐Hispanic whites (NHW). Methods A cross‐sectional study of 367 081 singleton liveborn first births to NHB and NHW women in California from 2008 to 2012 was conducted. Rate ratios (RR) were estimated for PTB and its subtypes—spontaneous and clinician‐initiated—after adjusting for confounders through Poisson regression. Universal age/race reference groups (NHW, 25‐29 years) and race‐specific reference groups (NHW or NHB, 25‐29 years) were used for comparisons. Results Among all women, RR of PTB was highest at the extremes of age (<15 and ≥40 years). Among NHBs, the risk of PTB was higher than among NHWs at all maternal ages (adjusted RR of PTB 1.38‐2.93 vs 0.98‐2.38). However, using race‐specific reference groups, the risk of PTB for NHB women (RR 0.91‐1.88) vs NHW women (RR 0.98‐2.39) was nearly identical at all maternal ages, with overlapping confidence intervals. Analyses did not demonstrate substantial divergence of risk with advancing maternal age. PTB, spontaneous PTB, and clinician‐initiated PTB demonstrated similar risk patterns at younger but not older maternal ages, where risk of clinician‐initiated PTB increased sharply for all women. Conclusions Primiparae NHBs demonstrated increased risk of PTB, spontaneous PTB, and clinician‐initiated PTB compared with NHWs at all maternal ages. However, RRs using race‐specific reference groups converged across maternal ages, indicating a similar independent effect of maternal age on PTB by race/ethnicity. A differential effect of maternal age does not appear to explain disparities in preterm birth by race/ethnicity.

Preterm birth, unplanned hospital contact, and mortality in infants born to teenage mothers in five countries: An administrative data cohort study

“…This sustained gradient effect of maternal age supports previous evidence on the importance of social, economic, and behavioural factors that predispose some young women to pregnancy, rather than biological immaturity, in explaining disparities in infant outcomes for teenage mothers 18 . It also contributes to the debate on maternal weathering, which posits that lifelong exposure to social and environmental disadvantage leads to broader disparities in health outcomes among disadvantaged populations 14,19 . Infants born to mothers aged <25 years represent a large proportion of births, particularly in England and Scotland (around 20%, compared with 15% in NSW and Ontario, and 13% in Sweden; Table ).…”

The epidemiologic characteristics and associated risk factors of preterm birth from 2004 to 2013 in Taiwan

“…This study highlighted a rising trend for preterm birth rate in Taiwan from 2004 to 2013. This finding was consistent with those of previous studies [29,30]. We found that provider-initiated preterm delivery was positively associated with the occurrence of preterm birth in this study.…”

Molecular Mechanism of Microbiota Metabolites in Preterm Birth: Pathological and Therapeutic Insights

“…Environmental and clinical factors such as toxicant particulate matter (PM 2.5–10, bisphenol, etc. ), consumption of a high-fat diet, family PTB history, low education, low socioeconomic status, ethnicity (PTB is higher in non-Hispanic black women), previous PTB history, multiple pregnancies, short pregnancy interval, early (<16 years) or late (>36 years) pregnancy, tobacco or alcohol consumption, high stress, hypertension, obesity, low body mass index, infection, short cervix, uterine anomaly, and miscarriage can affect fetal developmental plasticity, gestational age, or birth outcome [ 5 , 6 , 7 , 8 , 9 ].…”