The transfer of ethyl glucuronide across the dually perfused human placenta

Alcohol consumption during pregnancy can lead to Fetal Alcohol Spectrum Disorder (FASD), and because maternal self-reports are often unreliable, biomarkers of alcohol use are sometimes necessary to accurately determine fetal risk. Ethyl glucuronide (EtG), a direct metabolite of ethanol, has been detected in the meconium of infants born to mothers who consumed excessive alcohol during pregnancy. It is still unknown whether EtG detected in meconium originated from maternal hepatic glucuronidation of ethanol followed by subsequent placental transfer. Therefore, the objective of this study was to determine if EtG crosses the human placenta.

The transfer of EtG was measured using the ex vivo dual perfusion of an isolated human placental lobule. EtG (1 μg/mL) was added to the maternal circulation and samples were taken throughout the 1 h pre-experimental and 3 h experimental phases for measurement of EtG and markers of placental viability.

After 3 h, the fetal-to-maternal ratio was 0.29 ± 0.02 and net maternal-to-fetal transfer was still occurring. Triplicate averages of EtG concentrations in perfused placental lobules ranged from 140 to 414 ng/g tissue. Placental validation markers were within normal ranges for all perfusions.

The data show that EtG crosses the human placenta and primarily represents maternal exposure to alcohol.

This information can help with the development of more thorough biomarker screens for alcohol use during pregnancy.