OBJECTIVE:
To evaluate whether cannabis use during pregnancy was associated with depressive symptoms and whether ongoing use beyond the first trimester and higher amounts of cannabis use were associated with increased depressive symptoms.
METHODS:
This was a secondary analysis of the nuMoM2b (Nulliparous Pregnancy Outcomes Study: Monitoring Mothers to Be) study with participants enrolled from October 2010 to September 2013 at eight academic centers. Individuals with pregnancy outcome data who completed the EPDS (Edinburgh Postnatal Depression Scale) in the first and third trimesters and had available frozen stored urine samples were included. Cannabis exposure was ascertained by urine immunoassay for THC-COOH (11-nor-9-carboxy-delta-9-tetrahydrocannabinol); positive results were confirmed with liquid chromatography tandem mass spectrometry. Cannabis exposure groups for the primary analysis were classified as any exposure (positive urine assay at any of the three time points: 6 0/7–13 6/7 weeks of gestation, 16 0/7–21 6/7 weeks, and 22 0/7–29 6/7 weeks) or no exposure. In a secondary analysis, cannabis exposure was classified as no, only first trimester, or ongoing exposure beyond the first trimester. The primary outcome was depressive symptoms (EPDS score higher than 10) at 22–29 weeks of gestation. The association between cannabis exposure and later depressive symptoms was assessed with multivariable logistic. In an exploratory analysis, first-trimester urine THC-COOH was quantified to determine whether heavier use was associated with greater odds of depressive symptoms later in pregnancy.
RESULTS:
Of 10,038 nuMoM2b participants, 8,424 met the inclusion criteria, and 6.4% (n=535) were exposed to cannabis. Of those exposed, 32.1% (n=172) had only first-trimester exposure, and 67.9% (n=363) had ongoing exposure. Any cannabis use was not significantly associated with later depressive symptoms (adjusted odds ratio [aOR] 1.3, 95% CI, 0.97–1.6) compared with no exposure. However, ongoing exposure beyond the first trimester was associated with later depressive symptoms (aOR 1.6, 95% CI, 1.2–2.2). Higher levels of urine THC-COOH in the first trimester and across pregnancy were associated with increased odds of subsequent depressive symptoms.
CONCLUSION:
Any cannabis exposure was not associated with later-pregnancy increased depressive symptoms. However, ongoing use beyond the first trimester and higher levels of cannabis metabolite in first-trimester urine were associated with greater odds of depressive symptoms in later pregnancy. Directionality of this association cannot be determined given the study design.