Polydrug Use During Pregnancy and Preterm Birth in a Low-Income, Multiethnic Birth Cohort, Boston, 1998-2018

Objective: The opioid epidemic in the United States increasingly affects women of reproductive age and has resulted in a rise in concurrent polydrug use. The objective of this study was to investigate the effect of this polydrug use on preterm birth in a multiethnic birth cohort. Methods: We analyzed data from 8261 mothers enrolled in the Boston Birth Cohort from 1998 to 2018 in Boston, Massachusetts. We grouped substances used during pregnancy based on their primary effects (stimulant or depressant) and assessed independent and combined associations with smoking on preterm birth. Results: Of 8261 mothers, 131 used stimulant drugs and 193 used depressant drugs during pregnancy. The preterm birth rate was 27.5% (2271 of 8261) in the sample. Mothers who smoked had 35% increased odds of preterm birth across adjusted models. Mothers who used stimulant drugs without smoking were not at increased risk of preterm delivery compared with mothers who used neither (odds ratio [OR] = 0.69; 95% confidence interval [CI], 0.19-1.98), whereas mothers who used depressant drugs without smoking had more than twice the odds of having preterm delivery (OR = 2.31; 95% CI, 1.19-4.44), and infants were at risk of a 1-week reduction in gestational age (OR = −1.05; 95% CI, −2.07 to −0.03). Concurrently smoking and using depressant drugs was associated with increased odds of preterm birth (OR = 1.83; 95% CI, 1.28-2.61), as was concurrently smoking and using stimulant drugs (OR = 1.73; 95% CI, 1.14-2.59). Conclusions: Using stimulant drugs and depressant drugs during pregnancy is a risk factor for preterm birth. The individual and combined effects of using these drugs with smoking must be considered together to reduce the risk of preterm birth in the United States.