Combination anti-HIV treatment (HAART) has reduced the risk of mother-to-child HIV transmission to as low as 1%. But many pregnant HIV+ women wonder if elective cesarean section (C-section) can also help protect their babies.

Elective or planned C-sections are done before labor begins and before the mother's "water" (the membranes that surround the baby) breaks. This reduces the baby's contact with the mother's blood. (Emergency C-sections, those done after the membranes break, do not reduce HIV transmission.)

Early studies showed that C-sections lowered transmission rates. But this research was done before HAART was widely used. Today we know that HIV+ women who are on effective combination therapy and have undetectable viral loads have low transmission rates of 1% or less for vaginal births without C-sections.

Since C-sections require surgery, they carry some risks. Women who have C-sections are more likely to get infections than those who give birth vaginally. Also, because C-sections to prevent HIV transmission are done at about 38 weeks of pregnancy, there is a chance the baby could be delivered before its lungs are fully developed.

For a woman on HAART with a low viral load, a C-section is not likely to further reduce her already low risk of transmitting HIV. But for a woman with a viral load over 1,000 or one who is not already receiving treatment at the time of delivery, a C-section may reduce the chances of transmission.

The most recent federal guidelines recommend that each pregnant HIV+ woman discuss the possible risks and benefits of a C-section with her doctor before deciding. (See the federal guidelines for pregnant women at www.aidsinfo.nih.gov or call1-800-HIV-0440.)

Liz Highleyman is a medical writer and editor.