98 - The relation of hypertension to preterm birth rates among US-born and foreign-born Black women.

Poster Number: 98
Publication Number: 98.211

Davlyn Tillman, Baylor College of Medicine, Houston, TX, United States; James Collins, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, United States; Nana Matoba, Northwestern University, Chicago, IL, United States

Background: In the US, African-American women have a 1.6-fold greater preterm birth (PTB, < 37 weeks) rate than non-Latinx White women. Interestingly, US-born Black women have higher PTB rates than foreign-born Black women. Hypothesized upstream contextual factors include US-born Black women’s lifelong exposure to structural racial discrimination. Hypertension during pregnancy (HTN-PREG) and consequent development of placental hypoperfusion are established biologic risk factors for PTB, suggestive of a potential unifying downstream biologic mechanism.

Objective: To examine the relationship between HTN-PREG and PTB rates among US-born and foreign-born Black women.

Design/Methods: Stratified and multiple logistic regression analyses were performed on the 2017-18 U.S. natality files. The study population was limited to singleton live-births to non-Latinx Black women. Mother’s country of birth was defined as US-born or foreign-born. Co-variates examined include age, level of educational attainment, marital status, parity, prenatal care, and tobacco use. HTN-PREG was defined by the presence of chronic HTN, gestational HTN, or eclampsia.

Results: US-born Black women (Nf 697,226) had a PTB rate of 12.2 % versus 7.7 % for foreign-born Black women (Nf 158,184); RR = 1.6 (1.5, 1.6). US-born (compared to foreign-born) Black women had a greater incidence of HTN-PREG (Table). In both maternal nativity subgroups, HTN-PREG was associated with PTB rates (Figure). US-born and foreign-born black women with (compared to without) HTN-PREG had an increased risk of PTB, RR=2.5 (2.5, 2.6) and 3.6 (3.4, 3.7), respectively. In logistic regression models, the adjusted (controlling for maternal age, level of educational attainment, marital status, parity, prenatal care, and tobacco use) RR of PTB for US-born and foreign-born Black women equaled 2.6 (2.4, 2.7) and 3.5 (3.2, 3.6), respectively. Most striking, the population attributable risk of PTB for US-born and foreign-born Black women equaled 16.9% and 16.4%, respectively. Conclusion(s): Although US-born (compared to foreign-born) Black women have a greater prevalence of hypertension during pregnancy; it’s negative impact on PTB rates is attenuated among the former. Consequently, a similar relatively high proportion of preterm births to US-born and foreign-born Black women are attributable to hypertension during pregnancy.
Table 1. Hypertensive Disorder of Pregnancy (HTN-PREG) According to Maternal NativityF0BD292F-1C93-452F-A7B1-08B930BAEC9E.jpeg
Figure 1. Preterm Birth According to HTN-PREG Diagnosis9CB6CB24-7D76-48E5-8CF3-83B82B27AAFA_4_5005_c.jpeg