(901) Risks of Preterm Delivery and Small for Gestational Age Births Associated with Chronic Hypertension.

We designed a cross-sectional analysis utilizing data on all singleton live births in United States (US), 2015 to 2019, from the National Center for Health Statistics. PTD was defined as delivery at < 37 completed weeks. SGA birth was defined as sex-specific birthweight below the 10^th (SGA10), 5^th (SGA5), and 3^rd (SGA3) percentiles for gestational age. Associations were expressed as adjusted rate difference (RD) and adjusted risk ratio (RR) with their corresponding 95% confidence intervals (CI) using Poisson regression models with robust variance. The number needed to be exposed (NNE) were also estimated for PTD, SGA10, and preterm-SGA5 birth.


Results:

Among 18,556,590 pregnant people who delivered singleton live births in the US (2015-2019), rates of CHTN, PTD, and SGA10 birth were 1.9%, 7.2%, and 8.2%, respectively. Compared to normotensive pregnancies, CHTN pregnancies had higher rates of PTD (21.4% vs 7.8%), SGA10 birth (14.2% vs 10.3%), and preterm-SGA5 birth (2.1% vs 0.5%). The risks of PTD, SGA10 birth, and preterm-SGA5 birth were higher among non-Hispanic black (NHB) and Hispanic people compared to non-Hispanic white (NHW) people. The NNE for CHTN to have one PTD among pregnant people who were NHB, Hispanic, and NHW were 7.3 (95% CI 7.2, 7.4), 7.4 (95% CI 7.2, 7.6) and 9.8 (95% CI 9.6, 10), respectively (Table). The NNE for SGA10 and preterm-SGA5 birth were also lower for NHB and Hispanic people compared to the other race categories.


Conclusion:

Risks for PTB and SGA birth are higher among pregnant people with CHTN, and these risks were numerically greater for NHB and Hispanic people compared to NHW people. Preconception strategies to reduce the prevalence of CHTN among NHB and Hispanic people could reduce racial disparities in adverse perinatal outcomes.