Placental Transfer of Zidovudine in First Trimester of Pregnancy

Abstract

Zidovudine is one of the most common antiretroviral drugs used to prevent vertical transmission of human immunodeficiency virus. However, it is not recommended for use in the first trimester of pregnancy because of reservations about its potential teratogenicity during the organogenesis phase. The objective of this study was to investigate the placental transfer of zidovudine in the first trimester of human pregnancy. Twenty-six pregnant women were given 2 oral doses of zidovudine (200 mg) before first trimester surgical termination of pregnancy. Maternal blood, fetal tissue, and coelomic and amniotic fluid were collected for drug analysis. Zidovudine was detected in all samples of maternal serum and fetal tissue but present in only 7 samples of amniotic and coelomic fluid. Zidovudine concentration in fetal tissue was similar to that of maternal serum. The median fetal/maternal ratio was 0.92 and was not associated with gestational age (r = 0.03, P = .89). Zidovudine crossed the first trimester human placenta readily and achieved the level of maternal serum rapidly. Patients who choose to take zidovudine in first trimester of pregnancy should be counseled about the potential fetal effects.