Am J Obstet Gynecol MFM. 2021 Mar 20:100353. doi: 10.1016/j.ajogmf.2021.100353. Online ahead of print.
ABSTRACT
BACKGROUND: Non-Hispanic Black (NHB) maternal race is a known risk factor for preterm birth (PTB). However, the contribution of paternal race is not as well established.
OBJECTIVES: We sought to evaluate the risk of PTB among NHB, NH White (NHW), and mixed NHB/NHW dyads.
STUDY DESIGN: This is a population-based cohort study of all live births in the United States from 2015-2017, using live birth records from the National Vital Statistics System. Singleton, non-anomalous infants whose live birth record included maternal and paternal self-reported race as either NHW or NHB were included. The primary outcome was PTB <37 weeks’ gestation; secondary outcomes included PTB <34 and <28 weeks’ gestation, and delivery gestational age (as a continuous variable). Data were analyzed using chi-square, t-test, ANOVA, and logistic regression. A Kaplan-Meier survival curve was also generated.
RESULTS: There were 11,809,599 live births during the study period; 4,008,622 births met inclusion criteria. Of included births, 291,647 (7.3%) occurred <37 weeks’ gestation. Using the maternal race/paternal race convention, PTB <37 weeks’ gestation was most common among NHB/NHB dyads (n=70,987; 10.8%), followed by NHB/NHW (n=3,137, 9.5%), NHW/NHB (n=9,136, 8.3%), and NHW/NHW (n=209,387, 6.5%), p<0.001 for trend. Births <34 weeks’ (N=74,474) and <28 weeks’ gestation (N= 18,474) were also more common among NHB/NHB dyads. Specifically, 24,351 (3.7%) NHB/NHB, 1,017 (3.1%) NHB/NHW, 2,408 (2.2%) NHW/NHB, and 46,698 NHW/NHW dyads delivered <34 weeks, and 7,988 NHB/NHB (1.2%), 313 (1.0%) NHB/NHW, 584 (0.5%) NHW/NHB, and 9,589 (0.3%) NHW/NHW dyads delivered <28 weeks. NHW/NHW dyads delivered at a mean 38.8 ± standard deviation of 1.7 weeks’ gestation, while NHW/NHB, NHB/NHW, and NHB/NHB dyads delivered at 38.6 ± 2.0, 38.5 ± 2.3, and 38.3 ± 2.4 weeks’, respectively, p<0.001. Adjusted odds ratios (aORs) for the association between maternal/paternal race and PTB were highest for NHB/NHB dyads at each gestational age cutoff: aOR=1.60, 95% CI: 1.11,1.19 (<37 weeks’), aOR=2.47, 95% CI: 2.41,2.53 (<34 weeks’), and aOR=4.22, 95% CI: 4.04,4.41 (<28 weeks’) compared to the NHW referent group. Models adjusted for insurance status, chronic hypertension, tobacco use during pregnancy, history of prior PTB, and male fetus. In the Kaplan-Meier survival analysis, NHB/NHB dyads delivered earliest across the range of delivery gestational ages as compared to all other combinations of dyads.
CONCLUSIONS: NHB paternal race is a risk factor for preterm birth and should be considered when evaluating maternal a priori risk for prematurity. Future research should investigate the mechanisms behind this finding, including determining the contribution of factors such as racism, maternal and paternal genetics and epigenetics to an individual’s risk of PTB.
PMID:33757934 | DOI:10.1016/j.ajogmf.2021.100353
