Vertical transmission rate of HIV exposed twin pregnancies and associated factors in West Bengal, India; A retrospective cohort study.

Twin pregnancy is often associated with adverse obstetric outcomes. Mother to child transmission of HIV in twin pregnancy is less explored. The present study aimed to determine the risk of vertical transmission of HIV in HIV exposed twin pregnancy in comparison to singleton and to explore associated factors. We conducted a retrospective cohort study involving 348 HIV exposed babies (58 twin and 290 singleton) through systematic sampling from program database of West Bengal, India from April 2016 to March 2021. HIV vertical transmission rate was compared between single and twin live births. The effects of factors like maternal age, timing of maternal HIV diagnosis, duration of Antiretroviral Treatment, mode of delivery, birth weight and gender of baby etc. were determined. The HIV transmission rate for twin pregnancy (15.52% ) was significantly higher than single live-birth (5.5%) [Adjusted Odds Ratio = 3.08 (1.15-8.23)]. Among twin deliveries, maternal HIV diagnosis during intrapartum and postpartum period was associated with HIV transmission [Crude Odds Ratio= 11.0 (2.2-54.9)]. In conclusion perinatal HIV transmission is more common in twin pregnancies and linked with time of detection of maternal HIV. Early HIV detection and additional Antiretroviral regimen may be thought of for twin pregnancies.