Prenatal Tobacco, Alcohol, and Marijuana Use in the United States By Trimester

Background and Purpose: Prenatal substance use is associated with poor maternal and child health outcomes. Trimester is a potential protective factor that warrants further research. There is typically an inverse association between trimester and substance use. However, it is unknown whether this association is consistent trimester-to-trimester. Therefore, the objective of this study is to examine the overall and trimester-to-trimester trends in the association between trimester and prenatal tobacco, alcohol, and marijuana use – three of the most commonly used substances during pregnancy – among a nationally representative sample of pregnant women in the United States. 

Methods: In this cross-sectional study, pregnant women age 12-44 (N=732) were sampled from the 2016 United States National Survey on Drug Use and Health. Weighted logistic regressions (adjusted for age, race/ethnicity, and poverty status) were used to examine the association between pregnancy trimester and past month tobacco, alcohol, and marijuana use.

Results: The weighted sample was representative of approximately 2.3 million pregnant women. The prevalences of prenatal tobacco, alcohol, and marijuana use were 11%, 8.3%, and 5.0%, respectively. Prenatal alcohol (odds ratio [OR] = 0.18, p≤0.001) and marijuana use (OR = 0.16, p≤0.001) decreased significantly between the 1^st and 2^nd trimesters, but prenatal tobacco use did not decrease (OR = 0.79, p = 0.55). Prenatal tobacco use significantly decreased between the 2^nd and 3^rd trimesters (OR = 0.42, p<0.05), whereas alcohol (OR = 1.35, p = 0.53) and marijuana use (OR = 1.17, p = 0.77) did not decrease. Prenatal tobacco (OR = 0.33, p≤0.01), alcohol (OR = 0.24, p≤0.01), and marijuana use (OR = 0.18, p≤0.01) decreased in the 3^rd trimester relative to the 1^st.

Conclusions and Implications: Prenatal tobacco, alcohol, and marijuana use decreased as trimester increased when comparing the two endpoints (1^st and 3^rd trimesters). However, this inverse association was not consistent trimester-to-trimester. Practitioners should be aware that prenatal tobacco use may persist throughout mid-pregnancy, and significant decreases in use may not be observed until later in pregnancy, between the 2^nd and 3^rd trimesters. Contrarily, prenatal alcohol and marijuana use may decrease early in pregnancy, between the 1^st and 2^nd trimesters, with no significant reductions in use between the 2^nd and 3^rd trimesters. Selective or indicated prevention efforts are warranted to help prevent prenatal tobacco use early in pregnancy, and to prevent prenatal alcohol and marijuana use later in pregnancy. The overall negative trend in prenatal tobacco, alcohol, and marijuana use comparing the 1^st and 3^rd trimesters may mask important differences in substance use observed trimester-to-trimester, which can negatively impact fetal development and maternal health.