Abstract
Exposure to drugs of abuse, particularly during pregnancy, is difficult to ascertain. Presently, there is sparse information on gestational exposure and fetal effects to potentially toxic drugs such as methamphetamine (MA) and cocaine; two of the most prevalent abused stimulants in North America. The Motherisk laboratory at the Hospital for Sick Children routinely carries out analysis of MA and cocaine in adult and infant hair. All mother-child pairs in whom at least one had cocaine and/or benzoylecgonine (BE), or MA detected in hair were identified from the Motherisk database. Eleven mother-infant pairs with positive hair for MA were identified. One infant (9%) had a negative MA result with a positive maternal result. There was not any positive infant hair with negative maternal hair for MA. MA concentrations in mothers and infants correlated positively and were not significantly different. Median cocaine concentrations were tenfold higher in hair of the mothers compared to the infants. Thirty-nine (40%) infants had negative cocaine and BE with positive maternal results. Mothers whose infants were cocaine positive had median cocaine significantly higher than those whose infants were negative. Infants' cocaine in hair was positively correlated with maternal cocaine and BE. Infants' BE correlated with maternal cocaine and BE concentrations. Fetal hair grows during the last trimester of pregnancy; therefore a positive neonatal hair result indicates maternal use after pregnancy is known, a strong indicator of maternal addiction. To our knowledge, this is the first report on fetal exposure to MA during pregnancy showing transplacental transfer of the drug, with accumulation in fetal hair. Transplacental exposure to cocaine of babies of addicted mothers is highly variable. Further research is needed to understand the mechanisms leading to placental defense against cocaine.