Reproductive
Preconception Cannabis Use and Total Gestational Weight Gain in a North American Prospective Cohort Lauren A Wise* Lauren A Wise Krystal E Kuan Alyssa F Harlow Kenneth J Rothman Lisa M Bodnar
Background: The effects of preconception cannabis use on gestational weight gain (GWG) are not well studied.
Methods: We assessed the association between preconception cannabis use and total GWG in a North American prospective cohort of 5,423 females aged 21-45 years who delivered singleton births during 2014-2024. Participants reported their average frequency of cannabis use in the previous 2 months on baseline and bimonthly follow-up questionnaires during preconception. On the postpartum questionnaire, participants reported GWG in 5-lb categories, which we validated against birth records from 7 US states. We converted GWG (kg) to z-scores using gestational age- and BMI-specific charts and defined excess GWG as >1 SD (equivalent to >50 lb at term for normal-weight female). We used log-binomial regression to estimate risk ratios (RRs) for excess GWG and linear regression to estimate mean differences (β) in GWG z-scores by prepregnancy BMI (kg/m2), adjusted for preconception behaviors, SES, race, ethnicity, and medical history.
Results: Mean GWG was 31 lbs (SD: 13.6); 7% and 5% used cannabis <1 and ≥1 time/wk, respectively. Cannabis users were more likely than non-users to be younger, less educated, smoke cigarettes, and report higher perceived stress, depressive symptoms, and prepregnancy BMI. There was moderate agreement between self-reported and birth-record-abstracted GWG (weighted Kappa=0.64, 95%CI: 0.60-0.67). Cannabis use (≥1 time/wk vs. non-use) was associated with a higher risk of excess GWG: RR=1.47, 95%CI: 1.08-2.02 and the β in GWG (lbs) for a 40-wk delivery increased with greater prepregnancy BMI (BMI 18.5-24.9: 2.16, 95%CI: -0.09, 4.47; BMI 25-29: 3.08, 95%CI: -0.31, 6.64; and BMI ≥30: 4.09, 95%CI: 0.11, 8.32).
Conclusions: Preconception cannabis use ≥1 time/week was associated with a clinically-relevant increase in total GWG. The magnitude of the increase was larger among participants with greater prepregnancy BMI.