Marijuana Use During Pregnancy and Breastfeeding: Implications for Neonatal and Childhood Outcomes [pediatrics.aappublications.org]

Epidemiology

Data from 2016 reported in the National Survey on Drug Use and Health (NSDUH) revealed that 4.9% of pregnant women 15 through 44 years of age reported use of marijuana* in the past month, compared with 11% of nonpregnant women in the same age group.¹ This was an increase from the prior year, 3.4% and 10.3%, respectively. Among 18- through 25-year-old pregnant women, 8.5% reported past month marijuana use in 2016, compared with 3.3% of pregnant 26- through 44-year-old women. Although 2016 data are not available for pregnant 15- through 17-year-old women, 2012-2013 data revealed 14.6% reporting use of illicit† drugs in the past month. Among these illicit substances, marijuana is the substance most commonly used by pregnant women. Widely variable rates are reported among published studies in both the United States and the United Kingdom. Authors of a US multicenter lifestyle study in 2001 reported a prevalence of δ-9-tetrahydrocannabinol (THC), the psychoactive substance in marijuana, in infant meconium samples to be 7.2%.²Authors of a 2006 United Kingdom–based pilot study found that 13.25% of a cohort of Scottish newborn infants had meconium samples that had positive results for tetrahydrocannabinol and/or tetrahydrocannabinol-9-carboxylic acid.³ In studies of urban, young, and socioeconomically disadvantaged pregnant women, reported rates of marijuana use ranged between 15% and 28%.^4–6 Using NSDUH data from 2002 to 2014, Brown et al⁷reported that the prevalence of “past month” marijuana use among pregnant women 18 through 44 years of age increased from 2.37% to 3.84%, with the highest use rates reported in 18- through 25-year-old women (7.47% in 2014). Several state-specific surveys have also been used to document increasing rates of marijuana use among pregnant women. The Pregnancy Risk Assessment Monitoring System (PRAMS), a surveillance project of the Centers for Disease Control and Prevention and state health departments, collects state-specific, population-based data on maternal attitudes and experiences before, during, and after pregnancy (available at cdc.gov/prams). PRAMS has conducted surveys on a sample of women in Vermont with live births since 2001 and has included questions about marijuana use during pregnancy since 2009.⁸ In 2013, 9.4% of women in Vermont reported marijuana use during their pregnancy, with no significant change in rates since 2009. PRAMS data from Hawaii revealed that women who reported experiencing significant nausea during their pregnancy reported higher rates of marijuana use (3.7%) compared with pregnant women without nausea (2.3%).⁹ The 2012 NSDUH found that pregnant women reported a decrease in their marijuana use from 9.0% to 4.8% in the first and second trimesters, respectively, to 2.4% by the third trimester. Reported rates of tobacco use during pregnancy decreased from 19.9% to 13.4% and to 12.8% in the first, second, and third trimesters, respectively. Authors of other studies have found that 48% to 60% of marijuana users report continuing use during their entire pregnancy, believing it to be safer than tobacco.^4,10,11 In the Longitudinal Development and Infancy Study from the United Kingdom, Moore et al¹¹found that most pregnant women who used cocaine, ecstasy, methylenedioxymethamphetamine, and other stimulants stopped using these substances by the second trimester, but 48% of previous marijuana users continued to use marijuana as well as alcohol (64%) and tobacco (46%) throughout their entire pregnancy. In addition, the Longitudinal Development and Infancy Study revealed that the frequency and amounts of both marijuana and tobacco use were sustained throughout the entire pregnancy, similar to prepregnancy levels, whereas the extent of reported alcohol use was reduced. PRAMS data from Vermont also revealed that for 2013 births, 44.6% of women who reported being marijuana smokers before pregnancy continued to use marijuana during their pregnancy.⁸In contrast to these studies, Forray et al¹² found that, of 101 women who reported using marijuana at the beginning of pregnancy and who received substance abuse counseling, 78% were abstinent at a mean of 151 days later and remained abstinent until delivery.

Mark et al¹³ demonstrated in a retrospective cohort study of urban, predominantly African American women that, of patients receiving prenatal care and delivering at their institution, 21.8% initially had positive screen results for marijuana use (by either self-report or urine toxicology), but only 1.9% had positive urine screen results for marijuana at the time of delivery. They attributed their high rate of cessation of marijuana use during pregnancy to be related to opportunities for education about adverse effects of drug use, including tobacco and marijuana, during prenatal visits.¹³