Associations Between Cannabis Use and Sleep Outcomes in a Sample of Pregnant Women

Importance. Both sleep difficulties and cannabis use during pregnancy (CUP) are common and associated with adverse birth and offspring outcomes. Sleep problems are a commonly reported motive for cannabis use during pregnancy. Objective. Estimate associations between cannabis use during pregnancy and common sleep difficulties across trimesters. Design, Setting, and Participants. This cohort study recruited pregnant women with lifetime cannabis use who used (n=298) and did not use (n=143) cannabis during pregnancy. Women who reported heavy episodic alcohol consumption or use of other illicit substances were excluded. Some women tested positive for cotinine in urine drug screens. Exposures. Cannabis use was assessed at each trimester using self-report and urine drug screening. Presence of the nicotine metabolite, cotinine, was measured via urine drug screening at each trimester. Cannabis use during pregnancy (CUP) status was defined separately for each trimester as use versus no use and was treated as a time-varying exposure. The nicotine metabolite cotinine was included as a covariate in all models to account for nicotine exposure. Motivation for cannabis use during pregnancy was assessed during the first trimester. Main Outcomes and Measures. Insomnia symptoms (Women's Health Initiative Insomnia Rating Scale), daytime sleepiness (Epworth Sleepiness Scale), subjective sleep quality (Pittsburgh Sleep Quality Index single item), and restless legs symptoms were assessed at each trimester. Results. A CUP Status x Trimester interaction was observed for insomnia symptoms (F(2,737.81)=4.98, PFDR=0.03) wherein use during the third trimester was associated with heightened insomnia. Women reporting sleep difficulties as a motive for use reported worse insomnia symptoms (F(1, 223)=13.09, PFDR=0.001) and worse sleep quality (F(1, 219)=7.86, PFDR=0.01), relative to those using for other reasons. Conclusion. Elevated third trimester insomnia symptoms among pregnant women using cannabis compared to women who did not use cannabis suggest a potential trimester-sensitive association. Despite perceptions that cannabis improves sleep, women who reported sleep as their motive for CUP during the first trimester experienced greater insomnia symptoms and poorer sleep quality across pregnancy than those using cannabis for other reasons. Additional studies are needed to determine whether sleep-related difficulties precede cannabis use, follow it, are modified by it, or represent an epiphenomenon.