HIV and Pregnancy: Preventing Mother-to-Child Transmission

Current Guidance From U.S. Department of Health and Human Services

The prevention of mother-to-child transmission of HIV (also known as vertical transmission) encompasses all stages of pregnancy, from antenatal (before baby's birth) to postnatal (after delivery).

Women and/or their partners who are HIV positive can prevent verticle transmission by taking antiretroviral therapy (ART) over a long period of time in advance of pregnancy and delivery. The goal of therapy is viral suppression, which minimizes the risk of transmission.

Pregnant woman holding her stomach
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Reducing Antenatal Transmission Risk

The antenatal guidelines for ART for HIV-positive pregnant women include several modifications based on concerns about the effects of certain ARTs on the developing baby.

For women not previously on therapy, the U.S. Department of Health and Human Services (DHHS) recommends initial combination regimens to include a nucleoside reverse transcriptase inhibitor (NRTI) backbone like Retrovir (AZT, zidovudine) with Epivir (lamivudine) or Tenofovir/emtricitabine with an integrase inhibitor like Tivicay (dolutegravir) or a protease inhibitor.

NRTIs are shown to penetrate the placental barrier, providing the unborn baby with protection from HIV.

Other considerations include:

  • Viramune (nevirapine) should not be prescribed for women with a CD4 count over 250 cells/μL due to the increased risk of potentially life-threatening hepatotoxicity.
  • Intelence (etravirine), Edurant (rilpivirine), Aptivus (tipranavir), Selzentry (maraviroc), Lexiva (fosamprenavir), and Fuzeon (enfuvirtide) are not currently recommended due to insufficient data on their safety and effectiveness.
  • Viracept (nelfinavir) and Crixivan (indinavir) are not recommended due to suboptimal serum levels achieved during pregnancy unless no other options are available.

The guidelines currently do not recommend the use of Sustiva (efavirenz) or Sustiva-based drugs like Atripla during pregnancy, although this is largely considered a precautionary measure. While early animal studies had shown a high rate of Sustiva-related birth defects, the same has not been seen in humans.

If pregnancy is confirmed for a woman already on Sustiva, it is advised that the drug is changed only within the first five to six weeks of conception. After that, a change is not considered necessary.

Reducing Transmission Risk During Delivery

In the absence of ART, the risk of vertical transmission is estimated to be between 25 and 30%.

At the onset of labor, women who are taking antenatal ART should continue taking their medication on schedule for as long as possible.

According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 30% of women in the U.S. are not tested for HIV during pregnancy. Additionally, 15% of those infected with HIV receive either no or minimal antenatal care, while 20% do not initiate prenatal care until late in the third trimester.

HIV testing might not be done until the time of labor.

If a woman is confirmed as HIV-positive at the time of labor but has either:

  • Not received antenatal antiretroviral therapy
  • OR
  • Has a viral load greater than 400 copies/μL

Intravenous (IV, in a vein) AZT would be administered continuously throughout the course of labor.

Mode of Delivery Recommendations

Mothers who have an undetectable viral load at 36 weeks of pregnancy can have a vaginal delivery. The risk of vertical transmission in these situations is generally less than 1%. However, the risk is much higher for women who have a detectable viral load.

Evidence has shown that a scheduled cesarean section poses a far lower risk for vertical transmission of HIV than a vaginal delivery. When a cesarean section is done before the rupture of amniotic membranes, the newborn is less likely to be infected—particularly in cases where the mother has not achieved viral suppression.

The DHHS recommends that cesarean delivery is scheduled at 38 weeks of pregnancy if the mother:

  • Has not received ART during the course of her pregnancy
  • OR
  • Has a viral load greater than 1,000 copies/μL at 36 weeks of pregnancy.

In the event that a woman is seen for medical care after membrane rupture and with a viral load greater than 1,000 copies/μL, IV AZT is generally administered, sometimes with the use of oxytocin to expedite delivery.

Postnatal Recommendations

Upon delivery, Retrovir syrup is administered to the newborn within six to 12 hours of birth, continuing thereafter every 12 hours for the next six weeks. The dosage will be adjusted as the infant grows. An oral Viramune suspension may be also prescribed if the mother did not receive ART during pregnancy.

A qualitative HIV PCR test should then be scheduled for the infant at 14-21 days, one to two months, and four to six months of age. The qualitative PCR tests for the presence of HIV in the infant's blood—as opposed to the standard ELISA test, which tests for HIV antibodies. Since antibodies are largely "inherited" from the mother, their presence cannot determine whether the baby has been infected.

If the infant tests negative at one to two months, a second PCR would be performed at least a month later. A second negative result would serve as confirmation that vertical infection has not incurred.

An infant is only diagnosed with HIV after having two positive PCR tests. If the child is HIV-positive, ART would be immediately prescribed along with a Bactrim prophylaxis (used to prevent PCP pneumonia).

To Breastfeed or Not Breastfeed?

The long-and-short answer is that mothers with HIV in the U.S. are advised to avoid breastfeeding even if they are able to maintain complete viral suppression. In developed countries like the U.S., where infant formula is safe and readily available, breastfeeding poses an avoidable risk that arguably outweighs its associative benefits (e.g. maternal bonding, infant immune constitution, etc.)

While research into the use of antiretrovirals during postpartum breastfeeding is limited, a number of studies in Africa have shown transmission rates of anywhere between 2.8 to 5.9% after six months of breastfeeding.

The pre-chewing (or pre-mastication) of food for infants is also not recommended for HIV-positive parents or caretakers. While there have been only a handful of confirmed cases of transmission by pre-mastication, bleeding gums and sores, as well as cuts and abrasions that occur during teething can potentially raise the risk of transmission.

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