Objective: We investigated whether twin pregnancies were at increased risk of mother-to-child HIV-1 transmission (MTCT), in comparison with singletons.
Methods: Among HIV-1 infected women enrolled in the French Perinatal HIV Cohort (n = 9262), we studied the association between twin deliveries and MTCT rate according to three time periods (pre-1994, 1994-1996, 1997-2004) and the effect of birth order. The mother was considered to have transmitted if at least one of the twins was infected. Univariate and multivariate analyses of risk factors for MTCT were performed for deliveries in the periods up to 1996.
Results: Overall, 2.1% (192/9262) of all the deliveries were twins. The rate of prematurity was greater in twins than in singletons (54% and 13%, respectively). Up to 1996 the rate of MTCT of HIV-1 was 28.3% (15/53) in twin pregnancies, versus 13.5% (414/3077) in singletons [odds ratio (OR), 2.5; 95% confidence interval (CI), 1.4-4.7; P = 0.002; adjusted OR, 2.3: 95% CI, 1.1-2.3; P = 0.03). In the period from 1997 to 2003, MTCT was low and did not differ between twins (1.0%) and singletons (1.8%; P = 1.0). Overall, the transmission rate for the first-born child was threefold that for the second-born child (14/164, 8.5% versus 4/164, 2.4%; P = 0.008).
Conclusion: Twin pregnancies were at increased risk of transmission, but in the era of HAART this risk was reduced for twins, as well as singletons. Management of multiple pregnancies should take into account the risks of premature rupture of the membranes and preterm delivery.