Prevention of vertical HIV transmission: additive protective effect of elective Cesarean section and zidovudine prophylaxis. Swiss Neonatal HIV Study Group.

OBJECTIVE

To study the effect of elective Cesarean section and zidovudine prophylaxis on vertical HIV transmission.

DESIGN

Prospective study.

SETTING

Obstetric and paediatric clinics in Switzerland.

PARTICIPANTS

Children of mothers with HIV infection identified before or at delivery.

INTERVENTIONS: Routine use of elective Cesarean section for HIV-infected parturients by some Swiss centres since 1985. National recommendation for zidovudine prophylaxis in mid-1994.

MAIN OUTCOME MEASURE: HIV infection status of children.

RESULTS

In a cohort of 494 children born at least 6 months before the analysis date, 67 out of 414 children with known infection status were found to be infected, giving an overall transmission rate of 16.2% [95% confidence interval (CI), 13.0-18.51. Elective Cesarean section with intact membranes and without previous labour was associated with a lower transmission rate of 6% [odds ratio (OR), 0.29; 95% CI, 0.12-0.70; P = 0.006 versus other delivery modes]. Transmission rate was intermediate after spontaneous delivery 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 zidovudine 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 elective Cesarean section without zidovudine, 17% (four out of 24) after zidovudine alone, and 20% (55 out of 271) after no intervention.

CONCLUSIONS

Elective Cesarean section and zidovudine prophylaxis appear to have an additive effect in the prevention of vertical HIV transmission.