Nevirapine (Viramune) is safe for use in pregnant women^[1][2]. However, the use of nevirapine in pregnant women poses an elevated risk of liver toxicity, which has been fatal to mothers and foetuses^[3][4]. There is also evidence that blood levels of nevirapine are reduced in pregnant women, which may increase chances of developing resistance^[5].

Treatment with nevirapine during labour has also been shown to reduce mother-to-baby transmission of HIV. The advantage of nevirapine is that a single dose could be affordable even in developing countries where the cost of most anti-HIV drugs makes their use unrealistic. The key study showing nevirapine’s effectiveness in reducing HIV transmission was HIVNET 012, which compared a single dose of nevirapine to a short course of AZT during labour and during the first week of life in over 600 women in Uganda. At birth, the treatments were similarly effective, but after 14 weeks of breastfeeding, the rate of HIV infection was 13% in the nevirapine group and 25% in the AZT group^[6].

Later studies have demonstrated that single doses of nevirapine during labour, with or without a dose for the infant after birth can further reduce the risk of transmission when added to a course of AZT treatment^[7][8]. However, maternal exposure to nevirapine compromised subsequent triple therapy including nevirapine, even in women who did not have detectable NNRTI resistance^{[9][10][11][12]}. Consequently, in February 2004, the World Health Organization recommended that short course regimens of nevirapine monotherapy not be used where the standard regimens are available, because of the risk of nevirapine resistance and since AZT and combination therapy reduce transmission to a greater extent than nevirapine alone^[13]. This was followed in July 2004 by the South African Medicines Control Council recommending that nevirapine should no longer be used as the sole drug in short course treatment in preventing mother-to-child transmission. Despite this, recent evidence from a small South African study suggests that giving AZT and 3TC to women who have received short-course nevirapine during labour may reduce the risk that they will develop resistance to nevirapine^[14].

There is also evidence that breastmilk may a reservoir for nevirapine-resistant virus and that breastfed infants may be at risk of contracting a nevirapine-resistant form of HIV during the early weeks of life^[15]. Despite this risk, a recent study has shown that mothers who take nevirapine while breast-feeding produce levels of the drug in the milk high enough to prevent or reduce the risk of mother-to-child transmission in areas where there is no practical alternative to breast-feeding^[16].

For more information on the use of nevirapine and other anti-HIV drugs to prevent mother-to-child transmission of HIV, see Antiretroviral treatment during pregnancy.