Management of HIV in Pregnancy

Vertical transmission of human immunodeficiency virus from mother-to-child accounts for about 70% of the cases of HIV in children (in-utero transmission 30%, intrapartum transmission 70%).

• The prevalence of HIV infection in women giving birth in London in 2002 was 0.38%, compared with 0.06% in both the rest of England and in Scotland.¹
• The risk of mother-to-child transmission of HIV varies between 15% and 20% in non-breastfeeding women in Europe and between 25% and 40% in breastfeeding African populations.¹
• Risks of mother-to-child transmission is increased with: higher levels of maternal viraemia, HIV core antigens, lower maternal CD4 Count, primary HIV Infection during pregnancy, chorioamnionitis, other sexually transmitted disease, invasive procedures (e.g. fetal scalp electrodes, forceps, ventouse), rupture of membranes (especially if delivery is more than 4 hours after ruptured membranes), instrumental deliveries (i.e. forceps or vacuum), vaginal delivery, advanced maternal age and first born of twins born to an HIV infected mother.
• Factors that decrease risk of transmission are higher levels of neutralizing HIV antibody titres, elective Caesarean section, zidovudine, less invasive monitoring and intrapartum procedures.

• Mother-to-child transmission of HIV infection can be greatly reduced through early diagnosis of maternal HIV infection.
• Pregnant women should be offered screening for HIV early in pregnancy because appropriate antenatal interventions can reduce maternal-to-child transmission of HIV infection.¹
• Interventions to reduce mother-to child transmission of HIV during the antenatal period include antiretroviral therapy, elective caesarean section delivery and avoidance of breastfeeding after delivery.
• These interventions can reduce the risk of mother-to child HIV transmission from 30% to less than 2%.¹
• All pregnant women who are HIV positive should be screened and appropriately treated for genital infections during pregnancy. This should be done as early as possible in pregnancy and repeated at about 28 weeks.¹
• Presentation with symptoms or signs of pre-eclampsia, cholestasis or other signs of liver dysfunction during pregnancy may indicate drug toxicity and early liaison with HIV physicians is essential.¹

Drug therapy

• Anti-retroviral therapy is given to prevent mother-to-child transmission and to prevent maternal disease progression. The optimal regimen is determined on a case-by-case basis.
• Zidovudine is indicated for use in pregnancy for prevention of mother-to-child transmission of HIV but single-agent zidovudine therapy which does not suppress plasma viraemia to undetectable levels may allow the emergence of resistant virus.
• Potent combinations of three or more anti-retroviral drugs (HAART) have now become the standard of care. Women with advanced HIV should be treated with a HAART regimen. The start of treatment should be deferred until after the first trimester, if possible, and should be continued after delivery.
• Women who do not require HIV treatment for their own health require anti-retroviral therapy to prevent mother-to-child transmission. Anti-retroviral therapy is usually commenced between 28 and 32 weeks of gestation and continued intrapartum.¹ Anti-retroviral therapy is usually discontinued soon after delivery. Zidovudine is usually administered orally to the neonate for four to six weeks.
• Combination antiretroviral therapy maximises the chance of preventing transmission and represents optimal therapy for the mother but may increase the risk of drug toxicity to the fetus.
• The use of antiretrovirals to reduce mother-to-child transmission has resulted in resistant mutations and in the Paediatric AIDS Clinical Trials Group Protocol, 15% of the women developed nevirapine resistant mutations by 6 weeks' postpartum.²

Other interventions

• Elective Caesarean delivery with intact membranes or as soon as possible after rupture of membranes reduces the incidence of HIV in infants at 18 months compared with vaginal delivery.
• A zidovudine infusion should be started four hours before beginning the caesarean section and should continue until the umbilical cord has been clamped.¹
• Women who opt for a planned vaginal delivery should have their membranes left intact for as long as possible. Use of fetal scalp electrodes and fetal blood sampling should be avoided.¹
• Breastfeeding should be avoided as it increases mother-to-child transmission by approximately 15%.
• However in developing countries, where Caesarean section is unavailable and there is no alternative to breastfeeding, the WHO recommendations are that HIV-infected pregnant women who do not have indications for antiretroviral treatment, or do not have access to treatment, should be offered prophylaxis to prevent mother-to-child transmission using one of several regimens:³
  • Zidovudine from 28 weeks of pregnancy plus single-dose nevirapine during labour and single-dose nevirapine and one-week zidovudine for the infant. This regimen is very effective.
  • Alternative regimens based on zidovudine alone, short-course zidovudine plus lamivudine or single-dose nevirapine alone are also recommended.

• Mother-to-child transmission of HIV is largely preventable where universal antenatal HIV screening is undertaken, exclusive artificial formula feeding is feasible and where there is the provision for anti-retroviral therapy and delivery by caesarean section.¹
• In the absence of intervention, mother-to-child transmission was reported to occur in 25% of deliveries and was reduced to 8% with antiretroviral treatment with zidovudine.
• Combination antiretroviral therapy, Caesarean section and avoidance of breastfeeding can further reduce the risk of transmission to 1%.
• In the UK, mother-to-child transmission rates were 19.6% in 1993 and declined to 2.2% in 1998. Current data suggest that pregnancy has no effect on accelerating the development of AIDS, HIV-related diseases or severe immunosuppression for up to 1 year after delivery or abortion.⁴
• HIV infection may adversely affect pregnancy, especially in terms of the overall risk of spontaneous abortion and maternal postpartum endometritis.