abstract: BACKGROUND
  Studies of caesarean section and the rate of perinatal transmission of HIV-1 (RPT) have reported conflicting results if AZT was not administered simultaneously.
  
  
  METHODS
  To investigate the probable sources of error, 387 singleton pregnancies of HIV-1-infected mothers were enrolled in a prospective, observational study. To avoid contamination of the fetal mouth with maternal blood at caesarean section, the uterus was opened under careful preparation of the fetal membranes, maintaining their integrity as long as possible. To 105 pregnant women AZT was administered at various gestational ages (median 29th week), depending on the stage of the disease of the mother or obstetrical complications. The majority of newborns received AZT for 10 days I.V.
  
  
  RESULTS
  Group 1: For those, for whom vaginal delivery was intended (n=163, RPT=20.2%), this could be realized in 82% of the cases only. There was no significant difference in the RPT (23%-19,5%) between emergency caesarean section and vaginal delivery (odds ratio [OR]=1,25; 95% CI 0,41-3,44). Risk factors of fetal HIV infection (p≤0.05) were delivery <37thweek, rupture of membranes (ROM) ≥4 h, labor ≥5 h before delivery, CD4 ≤400 cells/µl, p24 antigenemia, and viral load. Group 2: If an elective caesarean section (n=119) was intended, the RPT (4,2%) was reduced compared to group 1 (OR=0.17; 95% CI 0.04-0,52; p=0.0002); however, in 16% emergency sections had to be performed because labor or ROM occurred before the planned date of elective caesarean section without difference in the RPT (4-5%) (OR 1,35; 95% CI 0,03-14,51). Significant risks (p≤0.05) of fetal infection were preterm labor and viral load. Group 3: If an elec- tive caesarean section under AZT (n=105) was intended, the RPT (1,3%) was significantly different to group 1 (OR=0,08; 95% CI 0.1-0.31; p=0.00003), but not to group 2 (OR=0.44; 95% CI 0.04-2.79). However, an elective caesarean section was feasible only in 74% without significant differences in the RPT (1,3-4%) (OR=2,96; 95% CI 0,04- 235,42). Except for the viral load (p=0.04), no risk factor was associated with fetal infection.
  
  
  CONCLUSIONS
  Elective and emergency caesarean section, performed early in parturition under surgical care to avoid contamination, significantly decreases the risk of fetal transmission, irrespec-tive of low CD4 cell counts, p24 antigenemia, viral load and ROM, but not preterm labor. Simultaneous administration of AZT in gestation and to the newborn further reduces the risk of peripartal infections and obviously provides additional safety at caesarean sections.
authors.affiliation: Kliniken für Geburtsmedizin und Pädiatrie, Charité, Humboldt Universität Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schäfer
authors.affiliation: Universitätsfrauenklinik Rostock, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Friese
authors.affiliation: Kliniken für Geburtsmedizin und Pädiatrie, Charité, Humboldt Universität Berlin, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Grosch-Wörner
authors.affiliation: Universitätshospital Zürich, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Lauper
authors.affiliation: Universitätshospital Zürich, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Hebisch
authors.affiliation: Universitätsfrauenklinik Frankfurt/Main, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Hugger