Disparities in Adverse Maternal Outcomes Among Asian Women in the US Delivering at Term

Disparities in maternal outcomes are representative of racial/ethnic health inequities in the US.¹ Recent data suggest that Asian women, even those considered at low risk, have higher rates of certain adverse outcomes in the peripartum period compared with White women.² Many studies are limited regarding outcomes for Asian women, either excluding them entirely or grouping diverse ethnicities despite known differences in culture, lifestyle, comorbidities, and risk.^3-5 Given the understudied nature of this increasing demographic of the US population, our objective was to assess the risk of maternal adverse outcomes at term for Asian women in the US according to ethnicity.

This population-based retrospective cohort study used US Vital Statistics data from 2014-2017. The study population was restricted to women with nonanomalous singleton pregnancies who labored and had live births between 37 and 41 completed weeks of gestation. Women whose self-reported race was Asian or White according to the 2003 revised birth certificate were included. Asian women were further subdivided by self-reported ethnicity: Asian Indian, Chinese, Filipina, Japanese, Korean, Pacific Islander, Vietnamese, or other. Institutional review board approval for the study was obtained from the University of Texas Health Science Center at Houston with a waiver of informed consent.

The main exposure variable was maternal race/ethnicity. Non-Hispanic White women served as the reference group. The primary outcome was a composite of adverse maternal outcomes, defined as any of the following: obstetric anal sphincter injury, admission to the intensive care unit, maternal blood transfusion, uterine rupture, or unplanned hysterectomy. Because of the high prevalence of obstetric anal sphincter injury relative to the other components of the composite outcome, a sensitivity analysis was performed with this injury excluded.

Maternal characteristics were compared using the χ² test for categorical variables. Rates of the composite outcome were reported as the number of cases per 1000 live births. Multivariable Poisson regression models were used to estimate the association between racial/ethnic group and the composite outcome while adjusting for possible confounders (eMethods in the Supplement).

For 15.8 million live births, 8 815 877 (56.5%) women met inclusion criteria. Of these women, 758 709 (8.6%) were Asian and 8 057 168 (91.4%) were White. Significant differences in baseline characteristics were observed between groups, including differences in education, marital status, insurance, prenatal care, and smoking (Table 1). Vaginal delivery rates were similar for Pacific Islander and Japanese women compared with White women, but lower for other groups. Women of all Asian ethnic groups had higher rates of gestational diabetes, but generally lower rates of neonates large for gestational age.

The risk for maternal morbidity among Asian women varied by ethnic group (Table 2). In the adjusted model, the risk of the composite adverse outcome was higher for all groups, except for Japanese women, compared with White women. Asian Indian mothers were most likely to experience the composite maternal outcome; the predominant component was obstetric anal sphincter injury (28.7 per 1000 live births). In the sensitivity analysis, increased risk persisted only for Filipina and Pacific Islander women.

Our results indicate variability in maternal risk across Asian ethnic groups, with an increased risk for most groups compared with White women. This increased risk was strongly driven by obstetric anal sphincter injury, which has previously been associated with Asian race/ethnicity.⁶ The reasons that Filipina and Pacific Islander women remained at increased risk in the sensitivity analysis are unknown and deserve further attention. In particular, research on social determinants of health, access to care, and structural racism is needed.¹ This analysis was limited to maternal outcomes reported in the data set; thus, some outcomes could not be analyzed. Our study highlights the need for specific data on racial/ethnic subgroups to fully appreciate maternal health disparities.

Accepted for Publication: July 31, 2020.

Published: October 9, 2020. doi:10.1001/jamanetworkopen.2020.20180

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Wagner SM et al. JAMA Network Open.

Corresponding Author: Stephen M. Wagner, MD, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Texas Health Science Center at Houston, 6431 Fannin St, MSB 3.270, Houston, TX 77030 (stephen.m.wagner@uth.tmc.edu).

Author Contributions: Dr Wagner had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: All authors.

Acquisition, analysis, or interpretation of data: Bicocca, Gupta, Chauhan, Mendez-Figueroa.

Drafting of the manuscript: All authors.

Critical revision of the manuscript for important intellectual content: Bicocca, Gupta, Chauhan, Mendez-Figueroa, Parchem.

Statistical analysis: Bicocca, Gupta.

Administrative, technical, or material support: Wagner, Mendez-Figueroa.

Supervision: Chauhan, Parchem.

Conflict of Interest Disclosures: Dr Parchem is supported by the Foundation for SMFM/American Association of Obstetricians and Gynecologists Foundation Scholar Award. No other disclosures were reported.