title: Placental transfer of Zidovudine in first trimester of pregnancy.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Obstetrics and Gynaecology, the Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong. nelsonsiu@cuhk.edu.hk
authors.forename: Shing-Shun
authors.initials: SS
authors.lastname: Siu
authors.forename: John Hok-Keung
authors.initials: JH
authors.lastname: Yeung
authors.forename: Man-Wah
authors.initials: MW
authors.lastname: Pang
authors.forename: Pui Yu
authors.initials: PY
authors.lastname: Chiu
authors.forename: Tze Kin
authors.initials: TK
authors.lastname: Lau
mesh_terms: D000029:Abortion, Legal; D000293:Adolescent; D000328:Adult; D019380:Anti-HIV Agents / Q000493:pharmacokinetics*; D005260:Female; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D008431:Maternal-Fetal Exchange; D008875:Middle Aged; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000378:metabolism*; D011275:Pregnancy, Unwanted / Q000378:metabolism; D015215:Zidovudine / Q000493:pharmacokinetics*
chemical_list: D019380:Anti-HIV Agents; D015215:Zidovudine