A large California cohort study shows that aggregating Asian American and Pacific Islander populations can obscure substantial differences in hypertensive disorder risk during pregnancy.
The risk of pregnancy-related high blood pressure differs substantially across Asian American, Native Hawaiian, and Pacific Islander subgroups, underscoring the importance of disaggregating data to better identify individuals at elevated risk, according to a large population-based study published in the Journal of the American Heart Association.1
Hypertensive disorders of pregnancy (HDPs)—including chronic hypertension, gestational hypertension, preeclampsia, eclampsia, and chronic hypertension with superimposed preeclampsia—are associated with serious maternal and neonatal complications. Although prior research has shown racial and ethnic disparities in HDP risk, Asian American, Native Hawaiian, and Pacific Islander populations are often analyzed as a single group, potentially masking meaningful differences within these communities.
To address this gap, investigators analyzed infant and fetal vital records linked with maternal hospital discharge data from California between 2007 and 2019. The retrospective cohort included 772,688 pregnant individuals who self-identified as Asian American, Native Hawaiian, or Pacific Islander and were categorized into 15 distinct subgroups. Chinese individuals, the largest subgroup, served as the reference population.
The prevalence of hypertensive disorders of pregnancy varied more than 3-fold across subgroups. Chinese individuals had the lowest prevalence, at 3.7% (n = 7,930), whereas Guamanian individuals had the highest prevalence, at 13.0% (n = 247). After adjustment for maternal sociodemographic and health-related factors, all Pacific Islander subgroups—including Hawaiian, Guamanian, Samoan, and Other Pacific Islander individuals—as well as Filipino individuals, remained at significantly higher risk for HDPs compared with Chinese individuals. In contrast, Korean, Vietnamese, and Japanese individuals tended to have the lowest risk and were not consistently at elevated risk relative to the reference group.
Across the highest-risk groups, adjusted relative risks were approximately 2-to-3-fold higher than those observed among Chinese individuals, even after accounting for factors such as age and other maternal characteristics. These findings suggest that differences in risk are not fully explained by commonly measured clinical or demographic variables.
“There are known ways to help prevent and treat high blood pressure during pregnancy. Our findings can help health care professionals identify those who are at higher risk,” said Jennifer Soh, MS, lead author of the study. “Early identification and treatment can help prevent serious, downstream complications for both the pregnant individuals and their infants.”2
The study adds important nuance to existing evidence on pregnancy-related hypertension. According to the American Heart Association, about 1 in 7 pregnancies in the United States is affected by a hypertensive condition, and these disorders are a leading cause of maternal illness and death. By highlighting heterogeneity within Asian American, Native Hawaiian, and Pacific Islander populations, the findings support more tailored prevention and monitoring strategies.
Researchers emphasized that structural and social determinants of health may contribute to the observed differences.
“The observed racial-ethnic differences in risk highlight the variation in lived experiences of the individuals included in this study,” Soh said, adding that future research should examine broader social and environmental factors that may drive elevated risk in some subgroups.
The authors acknowledged several limitations. The analysis relied on medical diagnostic codes, which may be subject to misclassification or underreporting. Additionally, the data were limited to California and may not be generalizable to other regions. The study period also preceded the COVID-19 pandemic, preventing assessment of pandemic-related effects on hypertensive risk during pregnancy.1,2
Overall, findings reinforced the need for disaggregated data in maternal health research across. Identifying subgroup-specific risk patterns may help clinicians improve prevention, screening, and management of hypertensive disorders of pregnancy, ultimately reducing adverse maternal and neonatal outcomes.1
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