No evidence of increased risk of MTCT with sequential pregnancies in UK and Ireland
Polly Clayden, HIV i-Base
Many HIV-positive women in the UK and Ireland have more than one pregnancy after their diagnosis. In 2009 40% of pregnancies in this population were sequential. The majority of these women will have received mother to child transmission (MTCT) interventions in previous pregnancies.
Clare French and colleagues from the MRC Centre of Epidemiology for Child House and UCL Institute for Child Health looked at whether sequential pregnancies are associated with increased MTCT risk.
Pregnancies in diagnosed HIV-positive women in the UK and Ireland are reported to the National Study of HIV in Pregnancy and Childhood (NSHPC).
The investigators analysed NSHPC data on live singleton births from 2000 to 2010. They compared the risk of detectable maternal viral load at delivery and of MTCT in sequential pregnancies with the risk in first reported index pregnancies. This included those in women with only one pregnancy. They conducted multivariate analyses using logistic regression.
During this period there were 10,154 pregnancies, of which 2099 (20.7%) were sequential. Of the sequential pregnancies, 1795 were 2nd; 274 were 3rd; and 30 were 4th or 5th.
The investigators found that 100% of sequential pregnancies (n=2099) were diagnosed prior to pregnancy, compared with less than half (43.5%) of index pregnancies (n=8055), p<0.001. They noted that sequential pregnancies were more common in the more recent period evaluated (5.5% in 2000-2003 vs 66.4% in 2008-2010) and were more likely to have vaginal deliveries. Women were also more likely to be receiving HAART at conception for subsequent pregnancies, p<0.001.
In multivariate analysis adjusted for year of delivery and treatment duration, the likelihood of having a detectable viral load at delivery did not differ significantly between index and subsequent pregnancies, p=0.77. Infant HIV infection status was available for >80% of births and there was no significant difference in mother to child transmission in a multivariate model adjusted for year of delivery, treatment duration and mode of delivery.
The investigators wrote: As the number of sequential pregnancies increases, and the treatment and management histories of women consequently become more complex, it is important that the situation be carefully monitored.
French C et al. Are sequential pregnancies in HIV-positive women associated with an increased risk of MTCT? 18th CROI, February 2011, Boston. Poster abstract 736.