Social Determinants of Health and Stillbirth

Robert M. Silver, MDThe stillbirth rate in the United States decreased slightly in the past few years and was 5.73 per 1,000 births in 2021.1 However, rates remain higher than most countries with similar resources.1–3 An important reason is the considerable disparity in stillbirth rates among various populations in the United States. For example, the rate in non-Hispanic White individuals was 4.85 per 1,000, as in many other countries. In contrast, rates for several other groups were substantially higher, including 9.89 per 1,000 for non-Hispanic Black individuals, 9.87 per 1,000 for Native Hawaiian and Pacific Islander individuals, and 7.48 per 1,000 for American Indian and Native Alaskan individuals.1 There is also an increased rate in individuals living in rural compared with urban areas,4 and there is considerable variation in rates among states. For example, rates are 3.91 per 1,000 in New Mexico compared with 10.00 per 1,000 in Mississippi.1 Reasons for these disparities remain unclear but persist after controlling for access to medical care, comorbidities, and risk factors such as obesity or age.5 In this issue of Obstetrics & Gynecology, Kawakita et al6 shed some light on the problem, showing that neighborhood deprivation is associated with an increased risk of stillbirth. They performed a retrospective cohort study of more than 60,000 births in a five-hospital medical system, assessing the relationship between neighborhood measures of social determinants of health (SDoH) and stillbirth. The Area Deprivation Index (ADI) is a neighborhood measure of SDoH focused on socioeconomic markers such as poverty, employment, education, and housing quality. Compared with the least deprived quartile, those in the other three quartiles had between a twofold and threefold increased risk of stillbirth.6 Individual SDoH are remarkably comingled, and quality data are not always available. Accordingly, a neighborhood measure such as the ADI provides a single datum that is easily available. The Maternal Vulnerability Index (MVI) and Social Vulnerability Index (SVI), two other neighborhood measures of SDoH were less clearly associated with stillbirth.6 These findings are consistent with other studies. Adams et al4 used a national inpatient U.S. database to show that individual SDoH risk factors are associated with a 60% increased risk of stillbirth. Markers associated with stillbirth included occupational risk, upbringing, and primary support group and family.4 Another study in the midlands and northern England showed unemployment to be independently associated with a more than twofold increase in late stillbirth.7 Area level deprivation also has been linked to perinatal mortality in a study from the United Kingdom8 and to stillbirth in a systematic review in high-resource settings.9 Thus, findings in the current study are likely robust. It is noteworthy that SDoH also are associated with most other adverse maternal, fetal, and neonatal adverse pregnancy outcomes.4 The authors propose that ADI score associated with deprivation be used to risk-stratify pregnant individuals at risk for stillbirth. This is a reasonable approach, because current American College of Obstetricians & Gynecologists’ recommendations are to consider screening for placental insufficiency, with antenatal testing such as nonstress tests for conditions increasing the risk of stillbirth at least twofold.10 Importantly, pregnant individuals at increased risk for stillbirth are also at increased risk for other adverse pregnancy outcomes, further justifying surveillance. Also, the ADI may prove even more predictive of stillbirth when combined with other clinical, ultrasound, or biomarkers. Numerous studies are underway using artificial intelligence and biomarker discovery to improve risk stratification for stillbirth. Ultimately, it will be important to perform risk stratification for all pregnant individuals to truly influence stillbirth occurrence, because many stillbirths occur in the absence of recognized risk factors.5 These data are welcome and further illustrate how SDoH relate to adverse pregnancy outcomes, including stillbirth. Further epidemiologic studies should strive to tease out which specific factors, behaviors, and pathophysiologic pathways contribute to adverse maternal and perinatal health. Ideally, the next steps are to identify strategies to mitigate the effects of SDoH on pregnancy. This is an incredibly complex problem that requires multiple strategies far beyond the scope of medicine to truly remedy. Shah et al11 propose a useful framework to mitigate the adverse perinatal effects of SDoH aimed at national-, regional-, health system–, hospital-, clinician-, and individual patient-level solutions. Examples of multipronged approaches include advocacy and lobbying for better health care access and public policy, use of digital health and technology to reach rural patients, and screening for and delivery of needed social services.11 In addition, trials should target novel biologic pathways that may mitigate pathophysiology leading to adverse outcomes, perhaps reducing chronic stress and placental damage. We are indebted to Kawakita and colleagues for highlighting the critical nature of SDoH and stillbirth. I hope these data will spur more work to develop strategies to successfully lessen the effects of SDoH on stillbirth and maternal and perinatal health.