206: Maternal marijuana exposure by self-report and umbilical cord sampling in a state with legalization

Abstract

To compare self-reported maternal marijuana use (survey and medical record abstraction) to quantitative biological sampling for 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-A) in umbilical cord homogenate. Cross-sectional study of women with a live, singleton pregnancy >24 weeks delivering at two urban medical centers in Colorado on 12 consecutive weekdays. Maternal marijuana exposure was estimated by (1) a survey detailing frequency and recency of marijuana use in pregnancy, (2) medical record abstraction of self-report to healthcare provider at time of admission, and (3) assay of the umbilical cord for THC-A. Cord segments were assayed for THC-A using liquid chromatography tandem mass spectrometry (LC-MS/MS). Limit of detection (LOD) for THC-A was 100 pg/g and limit of quantification (LOQ) was 200 pg/g. Women were categorized by survey-reported last use (≤30 days ago, 30 days to 1 year, more than 1 year, never), and the proportion of women with umbilical cord results positive for THC-A was reported for each group. Comparisons between groups were made using chi square. The relationship between survey-reported frequency of use in the past 30 days and quantitative THC-A cord homogenate result was evaluated using Spearman correlation. Of 166 eligible women, 136 (82%) were approached for the study; 9 declined participation, 8 cords were discarded by the clinical team prior to research collection and 2 cord samples were insufficient for assay, leaving 116 participants with surveys linked to cord assay results. Six percent of participants reported use in the last 30 days on survey whereas only 2.6% of participants reported marijuana use to healthcare providers at admission. On umbilical cord assay, 10.3% had THC-A above the LOQ and 22.4% had THC-A above the LOD. All women with survey-reported use in the last 30 days had a THC-A above the LOD, and cord results differed based on reported recency of use (Table). Survey-reported frequency of marijuana use in the past 30 days had moderate correlation with quantified umbilical cord THC-A (correlation coefficient 0.47, 95% CI 0.31-0.60, p<0.001; Figure). Umbilical cord sampling results in higher estimates of maternal cannabis use than self-report. Quantitative umbilical cord THC-A assay by mass spectrometry shows promise for measuring in utero marijuana exposure.View Large Image Figure ViewerDownload Hi-res image Download (PPT)