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Delivery by elective caesarean section reduced vertical transmission of HIV-1 infection

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The European Mode of Delivery Collaboration. Elective caesarean-section versus vaginal delivery in prevention of vertical HIV-1 transmission: a randomised clinical trial. Lancet. 1999 Mar 27;353:1035-9.

Intervention

Women were allocated to elective c-section at 38 weeks of gestation (n = 201) or to vaginal delivery (n = 235).

Main outcome measures

HIV-1 infection status in study infants confirmed by detection of virus (culture or polymerase chain reaction) on 2 separate specimens, persistence of antibody to HIV-1 beyond 18 months of age, or development of AIDS or death from an HIV-1­related cause.

Main results

Analysis was by intention to treat and by actual method of delivery. Of the 188 women allocated to c-section who had liveborn infants, 22 (12%) gave birth vaginally; of the 220 women allocated to vaginal delivery who had liveborn in-fants, 59 (27%) had a c-section. Fewer infants delivered by c-section had HIV-1 infection than did infants delivered vaginally. The reduction was apparent in the intention-to-treat analysis (P < 0.001) and in the actual method of delivery analysis (P = 0.009) (Table). No serious adverse events occurred in either group. Postpartum fever occurred in more women who delivered by c-section than in those who delivered vaginally (actual method of delivery analysis 6.7% vs 1.1%, P = 0.002).

Conclusion

In pregnant women with HIV-1 infection, delivery by elective caesarean section reduced vertical transmission of HIV-1 infection and was associated with no serious adverse events.

Sources of funding: Istituto Superiore di Sanitá-IV Progetto AIDS-Roma; U.K. Medical Research Council; European Commission.

For correspondence: Dr. F. Parazzini, Chief Analytical Epidemiology Unit, Istituto Mario Negri, via Eritrea, 62-20157 Milano, Italy. FAX 39-023546277.

Question

In pregnant women with HIV-1 infection, does elective caesarean delivery (compared with vaginal delivery) reduce the risk for vertical transmission of HIV-1 infection?

Design

Randomised, unblinded, controlled trial with follow-up in children to 18 months of age.

Setting

43 centres in Europe.

Patients

436 women who were between 34 and 36 weeks of gestation and had HIV-1 infection. Women who had an indication for caesarean section (c-section) or a non-obstetric contraindication to c-section were excluded. 408 women (mean age 28 y) had 410 liveborn infants. 370 infants (90%) were included in the analysis.

Elective caesarean section (c-section) vs vaginal delivery for preventing vertical HIV-1 transmission*

Analysis C-section Vaginal RRR (95% CI) NNT (CI)

Intention to treat 1.8% 10.5% 83% (48 to 95) 12 (8 to 25)

Method of delivery 3.4% 10.2% 66% (22 to 85) 15 (8 to 58)

*Abbreviations defined in Glossary; RRR, NNT, and CI calculated from data in article.

Commentary

The randomised controlled trial by the European Mode of Delivery Collaboration confirms the findings of several prospective studies and a meta-analysis (1). During the study period, good evidence became available that zidovudine given in pregnancy and perinatally reduces the incidence of transmission of HIV from mother to infant (2). An increasing number of women in the study were therefore receiving antiretro-viral therapy (ART). In the stratified analysis, the lowest rate of transmission (0.8%) was in the group allocated to delivery by c-section who also received ART during pregnancy. Because zidovudine mono- therapy is not optimal for treatment of HIV infection, many HIV-infected pregnant women are currently on a combination of agents.

Combination ART is more effective than zidovudine alone in lowering the viral load (3), and higher viral loads have been associated with a higher risk for transmission from mother to child (4). Therefore, it is hypoth-esised that the transmission rate would be lower for pregnant women taking such combinations. Results from small case series support this hypothesis. However, the toxicity for the fetus of many of these new antiretroviral agents is unknown. We now need to study the effect of elective c-section when combination ART is used in pregnancy.

Susan King, MD

The Hospital for Sick Children

Toronto, Ontario, Canada

References

1. The International Perinatal HIV Group. N Engl J Med. 1999;340:977-87.

2. Connor EM, Sperling RS, Gelber R, et al. N Engl J Med. 1994;331:1173-80.

3. Brun-Vezinet F, Boucher C, Loveday C, et al. Lancet. 1997;350:983-90.

4. Thea DM, Steketee RW, Pliner V, et al. AIDS. 1997;11:437-44.

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