Objectives: To estimate the incidence of first pregnancy in women living with perinatally acquired HIV (PHIV) in the United Kingdom and to compare pregnancy management and outcomes with age-matched women with behaviourally acquired HIV (BHIV).
Design: The National Study of HIV in Pregnancy and Childhood is a comprehensive, population-based surveillance study that collects demographic and clinical data on all pregnant women living with HIV, their children, and all HIV-infected children in the United Kingdom and Ireland.
Methods: The incident rate ratio of first pregnancy was calculated for all women of reproductive age who had been reported to the National Study of HIV in Pregnancy and Childhood as vertically infected children. These women and their pregnancies were compared to age-matched pregnant women with BHIV.
Results: Of the 630 women with PHIV reported in the United Kingdom as children, 7% (45) went on to have at least one pregnancy, with 70 pregnancies reported. The incident rate ratio of first pregnancy was 13/1000 woman-years. The BHIV comparison group comprised 118 women (184 pregnancies). Women with PHIV were more likely to be on combined antiretroviral therapy at conception and have a lower baseline CD4 cell count (P < 0.01 for both). In adjusted analysis, PHIV and a low baseline CD4 cell count were risk factors for detectable viral load near delivery; older age at conception and being on combined antiretroviral therapy at conception reduced this risk.
Conclusion: Women with PHIV in the United Kingdom have a low pregnancy incidence, but those who become pregnant are at risk of detectable viral load near delivery, reflecting their often complex clinical history, adherence, and drug resistance issues.