No increased in utero and peripartum HIV acquisition risk in HIV-exposed preterm infants.

Background: Limited data exist on the differential risk of HIV acquisition between infants born preterm versus those born at term to women living with HIV (WLHIV). With a reported increase in preterm delivery among pregnant WLHIV, understanding the risk of vertical transmission of HIV in preterm infants can inform strategies to optimise the timing of diagnostic testing, antiretroviral prophylaxis, and infant feeding.

Objectives: To describe the prevalence and timing of HIV acquisition, in utero versus perinatal, among infants with perinatal HIV exposure born prior to 37 weeks completed gestation age compared to those born at term in the Botswana-based Mpepu study and explore predictors of infant HIV acquisition.

Method: Using data extracted from the Mpepu study, we describe the prevalence, timing and risk factors for HIV acquisition in infants born preterm versus those born at term. Fisher exact testing was used to test for differences in prevalence and timing of HIV and a multivariable logistic regression model was used to assess risk factors for infant HIV acquisition.

Results: 2866 infants born to WLHIV were included in this secondary analysis. 532 (19%) were born preterm. There was no observed difference in the prevalence of HIV acquisition among infants born preterm versus at term overall (0.8% vs 0.6%, P = 0.54), at birth (0.2% vs 0.3%, P = 1.00) or between 14 and 34 days post-delivery (0.6% vs 0.3%, P = 0.41). The absence of maternal antiretroviral use during pregnancy significantly predicted infant HIV acquisition, with the risk of HIV acquisition reduced by 96% among infants whose mothers were taking antiretroviral treatment (ART) during pregnancy (adjusted odds ratio: 0.003, confidence interval: 0.01-0.02, P < 0.001).

Conclusion: There was no observed increase of in utero and peripartum HIV acquisition among infants born preterm following foetal exposure to HIV compared to those born at term.