Background: It is now accepted that the majority of HIV-1 vertical transmissions occur in late gestation and at the time of delivery. However, there is wide variation in the prevalence rate of mid-trimester vertical transmission. We assessed the maternal HIV-1 RNA viral load and in utero transmission during mid-trimester gestation.
Methods: Patients were enrolled when they decided to have their pregnancies terminated between 17 and 24 weeks of gestation. Prostaglandin-induced abortion with PGE1 analogue vaginal administration was carried out in all patients. Maternal plasma HIV-1 RNA viral load and plasma HIV-1 RNA (qualitative) from abortus heart blood were assessed.
Results: Amongst 41 HIV-1 seropositive pregnant women not receiving antiretroviral therapy plasma HIV-1 RNA was detected in the abortus heart blood from two women (4.9%; 95% confidence interval (CI), 0.6-16.5). Transmission occurred in one out of nine (11.1%; 95% CI, 0.3-48.2) with maternal viral load > or =100000 copies/ml versus one out of 32 (3.1%; 95% CI, 0.1-16.2) of those with <100000 copies/ml (P = 0.39).
Conclusions: The frequency of HIV-1 vertical transmission during mid-trimester was approximately 5% as detected by plasma HIV-1 RNA (qualitative) method in the fetuses aborted from the prostaglandin termination of pregnancy. During mid-trimester gestation there was no correlation between high maternal viral load and vertical transmission.