Transfer of inulin across the first-trimester human placenta

Objective: Our aim was to investigate the transfer of inulin from the mother to the first-trimester fetus. Study design: A bolus of inulin (5 mg/kg) was administered to nine healthy volunteers with pregnancies between 6 and 12 weeks of gestation scheduled for elective termination of pregnancy. Coelomic and amniotic fluid samples were obtained from the corresponding cavities between 8 and 25 minutes after the end of the bolus of inulin. Fetal fluid inulin concentrations were compared with those of matched samples of maternal blood and urine collected simultaneously. Results: Inulin was detected in all fetal and maternal samples. A trend toward an increasing inulin concentration was noted in the exocoelomic cavity with advancing time. Coelomic and maternal serum inulin concentrations were similar within 20 minutes after injection. Amniotic inulin concentrations were always lower than coelomic concentrations irrespective of gestational age or advancing time after injection. Conclusions: Inulin crosses the first-trimester human placenta from 7 weeks of gestation in quantities that yield measurable concentrations in both coelomic and amniotic fluids. These results suggest that the study of drug transfer in the first trimester of human pregnancy is feasible with use of samples obtained from the exocoelomic cavity.