Association Between Self-reported Prenatal Cannabis Use and Maternal, Perinatal, and Neonatal Outcomes

Abstract

IMPORTANCE Recent evidence suggests that cannabis use during pregnancy is increasing, although population-based data about perinatal outcomes following in utero exposure remain limited. OBJECTIVE To assess whether there are associations between self-reported prenatal cannabis use and adverse maternal and perinatal outcomes. DESIGN, SETTING, AND PARTICIPANTS Population-based retrospective cohort study covering live births and stillbirths among women aged 15 years and older in Ontario, Canada, between April 2012 and December 2017. EXPOSURES Self-reported cannabis exposure in pregnancy was ascertained through routine perinatal care. MAIN OUTCOMES AND MEASURES The primary outcome was preterm birth before 37 weeks' gestation. Indicators were defined for birth occurring at 34 to 36 6/7 weeks' gestation (late preterm), 32 to 33 6/7 weeks' gestation, 28 to 31 6/7 weeks' gestation, and less than 28 weeks' gestation (very preterm birth). Ten secondary outcomes were examined including small for gestational age, placental abruption, transfer to neonatal intensive care, and 5-minute Apgar score. Coarsened exact matching techniques and Poisson regression models were used to estimate the risk difference (RD) and relative risk (RR) of outcomes associated with cannabis exposure and control for confounding. RESULTS In a cohort of 661 617 women, the mean gestational age was 39.3 weeks and 51% of infants were male. Mothers had a mean age of 30.4 years and 9427 (1.4%) reported cannabis use during pregnancy. Imbalance in measured maternal obstetrical and sociodemographic characteristics between reported cannabis users and nonusers was attenuated using matching, yielding a sample of 5639 reported users and 92 873 nonusers. The crude rate of preterm birth less than 37 weeks' gestation was 6.1% among women who did not report cannabis use and 12.0% among those reporting use in the unmatched cohort (RD, 5.88% [95% CI, 5.22%-6.54%]). In the matched cohort, reported cannabis exposure was significantly associated with an RD of 2.98% (95% CI, 2.63%-3.34%) and an RR of 1.41 (95% CI, 1.36-1.47) for preterm birth. Compared with no reported use, cannabis exposure was significantly associated with greater frequency of small for gestational age (third percentile, 6.1% vs 4.0%; RR, 1.53 [95% CI, 1.45-1.61]), placental abruption (1.6% vs 0.9%; RR, 1.72 [95% CI, 1.54-1.92]), transfer to neonatal intensive care (19.3% vs 13.8%; RR, 1.40 [95% CI, 1.36-1.44]), and 5-minute Apgar score less than 4 (1.1% vs 0.9%; RR, 1.28 [95% CI, 1.13-1.45]). CONCLUSIONS AND RELEVANCE Among pregnant women in Ontario, Canada, reported cannabis use was significantly associated with an increased risk of preterm birth. Findings may be limited by residual confounding.

Opioid and Cannabis Use During Pregnancy and Breastfeeding in Relation to Sociodemographics and Mental Health Status: A Descriptive Study

“…At the same time in Canada, the legalization of non-medical cannabis use came into effect in 2018 [4] and reported use increased in the following year [5]. Prenatal exposure to cannabis has been associated with impairments to physical growth and cognition [6] and the chemical compounds in cannabis can be present in breast milk up to 6 days after maternal use [7]. Despite these major changes in the national landscape, there is a lack of information regarding use and predictors of these substances during pregnancy and postpartum.…”

Update on the developmental consequences of cannabis use during pregnancy and lactation

“…Results indicated a 70% increase in risk of small-forgestational age (SGA) infants in women who used cannabis during pregnancy. An elevated risk of SGA infants has been found in other studies using THC urine assays to confirm exposure (Rodriguez et al, 2019;Warshak et al, 2015) and in studies relying on maternal self-report (Corsi, Walsh, Weiss et al, 2019;Luke, Hutcheon, & Kendall, 2019;Saurel-Cubizolles, Prunet, & Blondel, 2014). The association between maternal cannabis use during pregnancy and SGA infants remained significant in a study where women cousing tobacco were excluded from the analysis (El Marroun et al, 2009).…”

“…When compared to unexposed controls, prenatallyexposed infants may also be at an increased risk for prematurity and reduced birthweight (Baer et al, 2019;Corsi, Walsh, Weiss et al, 2019;Howard, Dhanraj, Devaiah, & Lambers, 2019;Luke et al, 2019;Petrangelo, Czuzoj-Shulman, Balayla, & Abenhaim, 2019;Rodriguez et al, 2019). Despite research findings that suggest prenatal exposure is associated with changes in early growth trajectories, there is no robust evidence of an enduring negative effect.…”

Commentary – Marijuana use during pregnancy and premature birth: A problem likely to worsen

“…Previous studies have been marred by small numbers, faulty study design and lack of careful attention to confounders. A recent study of 661, 617 pregnant women in Canada appears to avoid these concerns [1]. The principal finding was a 2-fold higher rate of preterm birth less than 37 weeks' gestation among cannabis users during pregnancy (12.0% in cannabis users; 6.1% in nonusers).…”

“…This Commentary was provoked by three recent reports, concerning (1) the association between marijuana (cannabis) use during pregnancy and perinatal outcomes [1], (2) the increasing use of cannabis during pregnancy (see later), and (3) recent insights into the effects of cannabis on the developing brain [2]. Taken together, the data suggest that prenatal cannabis use has the potential to harm the developing brain and support the recent opinion of the Committee on Obstetric Practice of the American College of Obstetrics and Gynecology to discourage use of marijuana during pregnancy and lactation [3].…”