PREVENTION OF VERTICAL HIV TRANSMISSION - ADDITIVE PROTECTIVE EFFECT OF ELECTIVE CESAREAN-SECTION AND ZIDOVUDINE PROPHYLAXIS

Objective: To study the effect of elective Cesarean section and zidovu dine prophylaxis on vertical HIV transmission. Design: Prospective stu dy. Setting: Obstetric and paediatric clinics in Switzerland. Particip ants: Children of mothers with HIV infection identified before or at d elivery. Interventions: Routine use of elective Cesarean section for H IV-infected parturients by some Swiss centres since 1985. National rec ommendation for zidovudine prophylaxis in mid-1994. Main outcome measu re: HIV infection status of children. Results: In a cohort of 494 chil dren born at least 6 months before the analysis date, 67 out of 414 ch ildren with known infection status were found to be infected, giving a n overall transmission rate of 16.2% [95% confidence interval (CI), 13 .0-18.5]. Elective Cesarean section with intact membranes and without previous labour was associated with a lower transmission rate of 6% [o dds ratio (OR), 0.29; 95% CI, 0.12-0.70; P = 0.006 versus other delive ry modes]. Transmission rate was intermediate after spontaneous delive ry or non-elective Cesarean section (18%), and higher after obstetric interventions (27%; test for trend, P < 0.001). Since mid-1994, 78% of all women with registered pregnancies have received some form of zido vudine prophylaxis. Transmission rate was reduced from 17 to 7% after any zidovudine exposure (OR, 0.4; 95% CI, 0.11-1.41). Combined use of elective Cesarean section and zidovudine resulted in a 0% transmission rate (none out of 31), compared with 8% (seven out of 86) after elect ive Cesarean section without zidovudine, 17% (four out of 24) after zi dovudine alone, and 20% (55 out of 271) after no intervention. Conclus ions: Elective Cesarean section and zidovudine prophylaxis appear to h ave an additive effect in the prevention of vertical HIV transmission.