The human immunodeficiency virus is a retrovirus (Retroviridae family) which contains RNA. This virus affects the immune system and attacks CD4+ T-lymphocytes, macrophages and dendritic cells by attaching to the CD 4+ receptors expressed on the surface of these cells There are two types of HIV distinguished – HIV-1 and HIV-2. HIV-1 is more common, whereas HIV-2 is mainly found in West Africa.
The child may be infected while still in the womb, during the delivery or by breastfeeding.
- The transmission during pregnancy is relatively rare (especially if the mother-to-be receives antiretroviral treatment) as the mother’s blood and the blood of the fetus do not mix. When the prophylactic antiretroviral therapy is not administered to the mother during pregnancy, labor, and delivery, and to the fetus after birth, the possibility of HIV transmission from mother to infant/fetus is from 15 to 35% depending on the country.
- The highest risk (50-65%) of infecting the child occurs during vaginal delivery, so the Cesarean section is recommended to protect the child.
- Breastfeeding by an HIV-positive mother should be avoided when it’s possible as breast milk contains viruses.
Transmission during pregnancy
Every pregnant woman should be tested for HIV, as the early initiation of antiretroviral treatment provides better outcomes for the future mother and the unborn child.
It is believed that when a mother-to-be receives appropriate treatment during pregnancy the risk of HIV transmission to the fetus is reduced to 2%. Some conditions may increase the risk of vertical transmission, such as smoking, alcohol and drug abuse, other sexually transmitted diseases, malnutrition and high maternal viral load.
Treatment of HIV in pregnancy
A pregnant woman should receive antiretroviral treatment (ART) no matter what is the viral load. ART is considered to be safe for the fetus even when taken during the first trimester. D
- Didanosine and nelfinavir should be avoided during pregnancy.
- Stavudine and full-dose ritonavir is contraindicated in early pregnancy.
- Another drug efavirenz was reported to cause neural tube defects, however, there is not enough data that would prove this fact, so this medicine is still recommended as an alternative drug especially in poorer communities with limited resources.
- Monotherapy with zidovudine is considered to be totally safe for the child.
- Yet ART is associated with some pregnancy complications. Some studies suggest that combination ART therapy may increase the risk of preterm birth., especially when a protease inhibitor is administered.
- There is also a possible link between highly active ART (HAART) and risk of preeclampsia.
All HIV-infected women with HIV RNA >1,000 copies/mL near delivery should receive zidovudine intravenously during labor at a dose of 2 mg/kg, followed by an infusion of 1 mg/kg throughout labor. If the cesarean delivery is planned, the infusion should begin 3 hours before the procedure. C-section is considered for woman who has a viral load of more than 1000 RNA copies/mL.
All neonates who were exposed to HIVs should receive zidovudine during the first six weeks after they were born:
- < 30 weeks’ gestation: 2 mg/kg BID; after age 4 weeks – 3 mg/kg BID;
- >30 to < 35 weeks’ gestation: 2 mg/kg BID; after age 2 weeks – 3 mg/kg BID;
- >35 weeks’ gestation: 4 mg/kg BID;
Additional nevirapine (for infants of women who did not receive ART during pregnancy):
- Birth weight 1.5-2 kg: 8 mg/dose;
- Birth weight >2 kg: 12 mg/dose;