Studies suggest that the majority of mother-to-child HIV transmission (vertical transmission) occurs during labor and delivery, thereby fueling a debate about the safest route of child birth. This debate centers around the risks and benefits of Cesarean-section (abdominal surgical delivery) performed before the onset of labor (called elective C-section) versus natural, vaginal delivery.

Results from three recent studies suggest that elective C-section and the use of anti-HIV drug AZT (Retrovir®) may further reduce the risk of vertical transmission compared to what has been achieved by using AZT alone.* Results also suggest that elective C-section reduces the risk of vertical transmission independent of the effects of AZT. This procedure protects the baby from direct contact with the mother's HIV-containing genital tract secretions and blood. One study showed that elective C-section was associated with a lower vertical transmission rate compared to natural vaginal delivery among women receiving AZT (0.8% versus 6.6%, respectively).

While these studies appear to make a strong case for recommending elective C-section for HIV-positive women, none have looked at anti-HIV regimens other than the AZT regimen. These studies also did not measure HIV levels.

Studies in progress are testing whether combination therapy reduces vertical transmission rates more than the widely used AZT regimen. The same benefits offered by elective C-section and AZT therapy are likely reached with combination therapy, a regimen that results in more complete suppression of the mother's viral load. In this context, surgical delivery may be unnecessary.

Moreover, the risk of vertical transmission must be weighed against the dangers surgical delivery poses for the mother. Compared to vaginal delivery, elective C-sections have much higher rates of complications, including increased risk of hemorrhage (uncontrolled bleeding), infection and death. One study found HIV-positive women have post-operative complications three times as often as HIV-negative women. In immune compromised women, these complications are particularly dangerous.

At this time, it is unclear which route of delivery is best for both mother and baby. More studies are needed to determine the effect of triple-drug therapy on reducing vertical transmission; if viral load predicts the benefit of elective C-section; and if postoperative complications are associated with HIV infection. In the meantime, the decision to deliver vaginally or via C-section remains a matter of carefully considered medical opinion and personal choice.

*Note: In one major study, vertical transmission rates were 25% among women who did not receive anti-HIV treatment compared to 8% among women who received AZT. The study provided AZT (or placebo) to the mother after week 14 of pregnancy; to the mother through intravenous (in the vein) injection during labor; and finally to the newborn for six weeks after birth.

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