HIV infection in young children most commonly arises as a result of mother-to-child transmission (MTCT). It is thought that only 1.5-2% of MTCT occurs transplacentally during pregnancy. The vast majority occurs due to maternofetal transmission of blood during parturition or postnatal breast-feeding.
All pregnant women are recommended screening for HIV infection, syphilis, hepatitis Band rubella in every pregnancy at their booking antenatal visit. If a woman declines anHIV test, this should be documented in the maternity notes, her reasons should be sensitively explored and screening offered again at around 28 weeks.
A negative maternal HIV test at booking does not preclude neonatal infection - maternal infection and seroconversion can occur at any time during pregnancy and lactation. This is well-documented in countries with a high prevalence of HIV and has been seen in the UK.
• In the UK, the unlinked anonymous surveillance programme of 2006 revealed that 1 in 440 women giving birth in England and Scotland was HIV-positive.
• There is a 0.09% prevalence of previously undiagnosed HIV infection in pregnant women in the UK, with the largest focus in London (where the rate is 0.21%).
• The prevalence of HIV in UK-born women has increased by 66% from 1997 to 2006.
• The prevalence outside London has increased eightfold between 1997 and 2006.
• Without intervention, between 25-40% of babies born to HIV-infected mothers in the most severely affected countries are also infected. With appropriate interventions transmission rates can be reduced to less than 1%.
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Risk of mother-to-child transmission (MTCT)
This is increased with:
• Higher levels of maternal viraemia.
• HIV core antigens.
• Lower maternal CD4 count.
• Primary HIV Infection occurring during pregnancy.
• Co-existing other sexually transmitted disease (andmalaria - possibly[
• Invasive intrapartum procedures, eg fetal scalp electrodes, forceps, ventouse.
• Rupture of membranes (especially if delivery is more than 4 hours after the membranes ruptured).
• Vaginal delivery.
• Preterm birth
• Female babies more likely to be infected early (transplacental/perinatal routes).
• Advanced maternal age.
• The firstborn of twins (born to an HIV-infected mother).
Factors that decrease risk of transmission are:
• Higher levels of neutralising HIV antibody.
• Elective Caesarean section.
• Zidovudine (ZDV)
• Less invasive monitoring and intrapartum procedures.
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Mother-to-child transmission (MTCT) 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 MTCT of HIV infection.
• Interventions to reduce MTCT of HIV during the antenatal period include antiretroviral therapy, elective Caesarean section delivery and avoidance of breast-feeding after delivery.
• These interventions can reduce the risk of mother-to child HIV transmission from 25-30% to less than 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.
• 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.
Women who require HIV treatment for their own health should take highly active antiretroviral therapy (HAART) and continue treatment postpartum. They may also require prophylaxis against pneumocystic pneumonia (PCP), depending on their CD4 lymphocyte count.
Women already taking HAART and/or PCP prophylaxis before pregnancy should not discontinue their medication.
• Antiretroviral therapy is given to prevent MTCT and to prevent maternal disease progression. The optimal regimen is determined on a case-by-case basis.
• Zidovudine (ZDV) is indicated for use in pregnancy for prevention of MTCT of HIV but single-agent ZDV therapy which does not suppress plasma viraemia to undetectable levels may allow the emergence of resistant virus.
• Potent combinations of three or more antiretroviral 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.
• For women who do not require HIV treatment for their own health, HAART should be initiated between 20 and 28 weeks and discontinued at delivery. If they have a plasma viral load of less than 10,000 copies/ml and are prepared to be delivered by elective Caesarean section, an acceptable alternative is ZDV monotherapy initiated between 20 and 28 weeks, given orally, 250 mg twice daily, and intravenously started four hours before beginning the Caesarean section, continuing until the umbilical cord has been clamped. ZDV 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 MTCT 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.
In sub-Saharan Africa, access to services is improving. In 2008, 45% of HIV-infected pregnant women received antiretroviral treatment compared with 9% in 2004
A decision about mode of delivery should be made by 36 weeks of gestation.
• Delivery by elective Caesarean section at 38 weeks to prevent labour and/or ruptured membranes is recommended for:
• Women taking HAART who have a plasma viral load greater than 50 copies/ml .
• Women taking ZDV monotherapy as an alternative to HAART.
• Women with HIV and hepatitis C virus co-infection.
• A planned vaginal delivery can be offered to women taking HAART who have a plasma viral load of less than 50 copies/ml. 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.
• Delivery by elective Caesarean section for obstetric indications or maternal request should be delayed until after 39 weeks in women whose plasma viral load is less than 50 copies/ml, to reduce the risk of transient tachypnoea of the newborn.
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.
Breast-feeding should be avoided as it increases MTCT by approximately 15%. However, in developing countries, where Caesarean section is unavailable and there is no alternative to breast-feeding, the World health Organization (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 MTCT, using one of several regimens:
• ZDV from 28 weeks of pregnancy plus single-dose nevirapine during labour and single-dose nevirapine and one-week ZDV for the infant. This regimen is very effective.
• Alternative regimens based on ZDV alone, short-course ZDV plus lamivudine or single-dose nevirapine alone are also recommended.
Mother-to-child transmission (MTCT) of HIV is largely preventable where universalantenatal HIV screening is undertaken, exclusive artificial formula feeding is feasible and where there is the provision for antiretroviral therapy and delivery by Caesarean section.
• In the absence of intervention, MTCT transmission was reported to occur in 25% of deliveries and was reduced to 8% with antiretroviral treatment with zidovudine (ZDV).
• Combination antiretroviral therapy, Caesarean section and avoidance of breast-feeding can further reduce the risk of transmission to 1%.
• In the UK, MTCT 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 orabortion.
• HIV infection may adversely affect pregnancy, especially in terms of the overall risk of spontaneous abortion and maternal postpartum endometritis.
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