Pre-pregnancy substance use and first trimester cardiovascular health among nulliparous pregnant people: The nuMoM2b Study.

Background: Suboptimal pre-pregnancy health, including substance use and cardiovascular risk factors, is associated with higher risks of maternal-foetal morbidity and mortality.

Objective: To determine if pre-pregnancy substance use is associated with early pregnancy cardiovascular health (CVH). It is hypothesised that pre-pregnancy use of substances is associated with worse CVH in the first trimester of pregnancy.

Methods: This is a secondary analysis from the 2010-2015 United States nuMoM2b cohort (n = 9895). Pre-pregnancy alcohol, tobacco, marijuana, and illicit substance use were assessed through questionnaires. Latent class analysis categorised participants based on their 3-month pre-pregnancy or ever(*) substance use: (1) Illicit substances*, marijuana*, and alcohol use (n = 1234); (2) marijuana* and alcohol use (n = 2066); (3) tobacco and alcohol use (n = 636); and (4) alcohol only use (n = 3194). The referent group reported no pre-pregnancy substance use (n = 2765). First trimester CVH score from 0 (least healthy) to 100 (most healthy) was calculated using a modified American Heart Association Life's Essential 8 framework and included body mass index (BMI), blood pressure, blood glucose, non-HDL cholesterol, diet, sleep, and physical activity. Multiple linear regression evaluated the relationship between pre-pregnancy substance use classes and CVH scores.

Results: CVH score varied by class: No substance use (mean: 65, SD: ±1.3), illicit substances*, marijuana*, and alcohol use (68 ± 1.3), marijuana* and alcohol use (67 ± 1.3), tobacco and alcohol use (62 ± 1.4), and alcohol only use (67 ± 1.3). In adjusted models, those who used tobacco and alcohol compared to the no substance use class had a lower CVH score (-2.82); other classes had scores ranging from 1.81 to 2.44 points higher than the no substance use class. Individual CVH component scores followed similar patterns.

Conclusions: All groups, but most markedly those who used tobacco and alcohol prior to pregnancy, began pregnancy with only moderate CVH and may benefit from CVH promotion efforts along with substance use treatment.