Alcohol, Tobacco and Illicit Drug Use During Pregnancy in the Longitudinal BELpREG Cohort in Belgium Between 2022 and 2024.

Background/Objectives: Substance use during pregnancy is associated with adverse outcomes for both mother and child. This study aimed to determine the prevalence and determinants of alcohol, tobacco and illicit drug use before and during pregnancy in Belgium. Methods: An observational study was conducted using data from the longitudinal BELpREG registry. The study included women aged 18 years or older who completed at least one questionnaire on substance use during pregnancy between 2022 and 2024. Data were analyzed using descriptive statistics and logistic regressions. Results: In total, 1441 women were included. Preconception prevalences of alcohol, tobacco and illicit drug use were 82.2%, 10.0% and 4.2%. These self-reported prevalences dropped in the first trimester to 12.9%, 4.1% and 0.6%, respectively. Considering the rates of substance use in pregnancy but before pregnancy awareness, the overall prevalence of alcohol, tobacco and illicit drug use in the first trimester was 41.0%, 6.6% and 1.2%, respectively. Women with a higher education (aOR (adjusted odds ratio), 2.12; 95% CI (confidence interval): 1.14-3.96), unplanned pregnancies (aOR, 2.88; 95% CI: 1.77-4.67), spontaneous pregnancies (aOR, 2.94; 95% CI: 1.51-5.75), cohabitants drinking alcohol daily (aOR, 2.01; 95% CI: 1.09-3.70), and those using tobacco in the first trimester (aOR, 5.37; 95% CI: 2.70-10.66) were more likely to report alcohol use. In addition, women with a lower education (aOR, 7.67; 95% CI: 3.76-15.67), unplanned pregnancies (aOR, 3.31; 95% CI: 1.53-7.15), cohabitants using tobacco (aOR, 9.11; 95% CI: 4.48-18.52), and those who used alcohol (aOR, 6.67; 95% CI: 3.07-14.64) or illicit drugs (aOR, 39.03; 95% CI: 3.72-409.83) in the first trimester were more likely to report tobacco use. Conclusions: Despite a significant reduction in substance use in pregnancy compared to before pregnancy, a relevant portion of women continue to use substances, particularly in the early stages before pregnancy awareness. Targeted public health interventions and (more) awareness among caregivers are needed to further promote substance use cessation before conception.