Interventions for reducing MTCT
- Interventions known to reduce risk of MTCT include: antiretroviral therapy for mother and baby, elective Caesarian section (ECS) and avoidance of breast-feeding or exclusive breast-feeding.
- Antiretroviral therapy reduces viral load in the mother can thus reduce the risk of MTCT, although it is only one factor responsible for the same. The risk of fetal toxicity has to be considered in using ARV drugs during pregnancy. Most ARV Drugs are FDA category B or C, but efavirenz is category D and is contraindicated in first trimester of pregnancy.
- Various regimens have been studied for reducing risk of MTCT. Most of the studies have shown reasonable success using one or more ARV Drugs (in women who do not need ART for their own HIV status) around delivery in reducing MTCT rates. A single dose of NVP at the onset of labor and within 72 hours of birth for the baby has been shown to reduce the risk of HIV transmission to the baby.95 However, there is evidence to suggest that resistance to single dose NVP is frequent and this can compromise the mother’s NVP based regimen in the future.96 Hence, as far as possible single dose NVP should not be used for MTCT purposes. Even in the situation where the mother presents in labor a combination of ZDV+3TC should be added to single dose NVP and continued for 7 days after delivery to reduce risk of development of NVP resistance.
- In mothers (with CD4 counts>250/mm3) who can afford and therapy can be closely monitored, a combination of standard 3 Drug ART is recommended for reducing risk of MTCT. This option termed as START (Short-term antiretroviral therapy) intends to treat mothers with standard three Drugs ART throughout the duration of pregnancy (except first trimester) and discontinuing shortly after delivery.97 The advantage of this approach is achieving maximal suppression of HIV and prevention of ARV resistance development, which would not compromise mother’s future therapeutic options.
- The choice of ARV drugs depends on ARV treatment history of the infected mother and her husband. The husband’s treatment history is important to evaluate possibility of resistant virus should his viral load not be undetectable after 6 months of his own treatment.
- Since NVP cannot be used in mothers with CD4 count > 250/mm3, and experience with the use of EFV after first trimester is limited, PI based regimens is recommended for START. Though standard boosted PIs are otherwise recommended, in pregnancy most experience relates to nelfinavir use.98 Nelfinavir should be used in the doses of 1250 mg bid to account for changes in pharmacokinetics during pregnancy. Evidence on the risk of prematurity in women using PI is still conflicting. However, blood glucose levels need to be monitored periodically in these women. Infants born to such mothers should receive ZDV 4 mg/kg bid for 6 weeks.
In women who cannot afford a standard 3-Drug regimen following option may be recommended: 99
ZDV from 28 weeks of pregnancy plus single dose of NVP during labor and single dose NVP and one week ZDV for the infant. This approach has shown to be highly effective.100
Mode of delivery also impacts MTCT rates. Elective cesarean section (ECS) is an efficacious intervention among HIV infected mothers not taking ARVs or on ZDV monotherapy alone. The risk of post-partum morbidity is slightly higher than vaginal delivery but lower than emergency cesarean section.101 The risk of MTCT according to mode of delivery in mothers with low viral loads (e.g. due to potent ART) is less clear, but most experts would recommend a vaginal delivery if mothers viral load around delivery is 1000 copies/ml.102 If viral load determinations are not possible, then an ECS is recommended for all women. ECS should be performed before the onset of labor and rupture of membranes.
Transmission via breast-feeding is an important risk for transmission of HIV to infants and mothers should be informed about the same. The choice of whether to breast-feed or not finally should be made by the mother after the risks and benefits of the same are clearly explained to her. The benefits of breast-feeding are obvious and the risk of morbidity associated with top feeding may be significant.103 This study was conducted in a public sector hospital where access to safe top feeds may be limited. Exclusive breast-feeding is another option, where in the baby is fed only mothers milk. Studies have demonstrated that mixed feeding is the riskiest for MTCT.104 Current UNAIDS/WHO/UNICEF recommendations stress avoidance of all breast-feeding if replacement feeding fulfills the key requirements of being affordable, feasible, acceptable, sustainable, and safe. The decision of breast-feeding or not should hence be individualized according to the mother’s circumstances. Fig. 2 summarizes approach for managing an HIV infected pregnant woman.