1115: Measurement of prenatal marijuana use with bioassays and survey data

Abstract

There is no gold standard for measurement of marijuana (MJ) use in pregnancy, and ethics preclude traditional pharmacokinetic studies. We aimed to evaluate the correlation of bioassays and detailed self-reported use in a longitudinal cohort of pregnant women in a state with legal recreational and medicinal MJ. Prospective longitudinal cohort of pregnant women (< 16 weeks singleton) identified by self-reported MJ use in the Denver metro area. The study involved a written self-report survey and metabolite detection in biospecimens at 4 longitudinal study visits (Table). Maternal urine and sera were tested for presence (>5ng/mL) of 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH). Liquid chromatography tandem mass spectrometry was used to quantify THC-COOH in umbilical cord homogenate. Cessation of use was defined as no reported use and negative serum and urine. Last MJ use was recorded to evaluate time frame over which THC-COOH remains detectable (>100pg/g) in cord. Spearman correlation was assessed between the bioassays and self-report. 50 pregnant women enrolled. 33 of 50 (66%) met the definition of MJ cessation prior to delivery (Table). Sera and urine results were strongly correlated with self-reported use at all study visits (Spearman correlation coefficient range 0.70-0.87 across visits, p< 0.001). 36 cord samples were collected at delivery (9 lost to follow-up, 2 miscarriages, 1 withdrew, 2 cords discarded). There were no positive cord results when MJ use stopped before 22 weeks. Among 6 women with use at the 32-36 week visit, 1 had detectable cord THC-COOH, and among 17 with ongoing use at delivery, 15 (88%) had cord THC-COOH. Frequency of MJ use in the past 30 days by self-report at delivery had strong correlation with quantified cord THC-COOH (Figure). Quantification of THC-COOH in cord homogenate strongly correlated with frequency of maternal MJ use in the last month of pregnancy. Earlier use can be measured by urine or serum assay. Together, these assays may allow for quantitative measurement and assessment of perinatal effects of MJ.View Large Image Figure ViewerDownload Hi-res image Download (PPT)