Influence of short-course antenatal antiretroviral therapy on viral load and mother-to-child transmission in subsequent pregnancies among HIV-infected women

Background: HIV-infected women not requiring treatment for their own health usually receive short-course antiretroviral therapy (ART) during pregnancy. Little is known about the effect of this on response to HAART in subsequent pregnancies. Methods: We analysed data from the UK and Ireland's National Study of HIV in Pregnancy and Childhood for 2000-2010. Analyses were restricted to live births among women not on ART at conception but receiving antenatal HAART. We compared risk of detectable viral load at delivery and mother-to-child transmission in two pregnancy groups: 'ART-naive' and 'HAART-experienced' (>= 7 days of HAART during previous pregnancy). Multivariable analyses were conducted using logistic regression. Results: There were 5,372 pregnancies in the ART-naive group and 605 in the HAART-experienced group. Overall, there was weak evidence of an increased risk of detectable viral load in the HAART-experienced group (adjusted odds ratio [aOR] 1.27; 95% CI 1.01, 1.60); however, the increased risk was apparent only among women who previously received non-nucleoside reverse transcriptase inhibitor-based HAART (aOR 1.81; 95% CI 1.25, 2.63), and not among those with previous protease-inhibitor-based HAART exposure (aOR 1.08; 95% CI 0.81, 1.45). There was no difference in mother-to-child transmission risk between the ART-naive and HAART-experienced groups (aOR 0.42; 95% CI 0.10, 1.78), although the number of transmissions was small. Conclusions: We found no increased risk of detectable viral load at delivery among women exposed to short-course, protease-inhibitor-based HAART during a previous pregnancy. However, women with prior exposure to non-nucleoside reverse transcriptase inhibitor-based HAART appeared to be at increased risk of not adequately suppressing the virus. These findings highlight the need for careful management of HIV-infected women presenting with repeat pregnancies.