Background:
Stillbirth is a major health issue, but relatively little research has been conducted to determine whether drug use increases the risk of stillbirth. The objective of this cross-sectional study was to determine whether any history of drug use was associated with stillbirth in the United States. Effect modification by ethnicity was considered as a secondary objective.

Methods:
Data were drawn from the National Health and Nutrition Examination Survey between 2009-2018 and included women between the ages of 20-59 years. Multivariate survey design-adjusted logistic regression was conducted. Effect modification by ethnicity was assessed using simple slopes analysis. Missing data were imputed using multiple imputation by chained equations.

Results:
Among 6,045 participants, drug use was associated with higher odds of stillbirth after adjusting for confounding, but this was not statistically significant (OR 1.13, 95% CI 0.80;1.62). Among Hispanic women, drug use was associated with significantly lower odds of stillbirth (OR 0.54; 95% CI 0.23;0.84). No significant interactions with drug use were identified among other ethnicities.

Discussion:
The primary analysis found no statistically significant association between drug use and stillbirth, but this relationship may be modified by ethnicity. The small number of events identified in the dataset likely explains the lack of statistical significance identified, and the unexpected findings among Hispanic women. Further exploration into this potential effect modification is warranted to ensure pregnant people who use drugs receive prenatal care that best meets their needs.