OBJECTIVE

To examine the risk of preterm birth (PTB) and small for gestational age (SGA) among women with HIV compared to women without HIV. Secondary objectives were to explore the role of maternal immune activation (IA) and effect of cART timing on these outcomes.

DESIGN

Prospective observational cohort.

SETTING

Urban government-run clinic at Chawama Hospital in Lusaka, Zambia.

PARTICIPANTS

A total of 1481 women with and without HIV with singleton pregnancies enrolled before 26 weeks' gestation by ultrasound dating.

METHODS

From August 2019 to November 2022, pregnant women were enrolled in a 1 : 1 ratio of HIV infection. Maternal baseline clinical factors were collected, as well as CD4 + , viral load and CD8 + T-cell IA in women with HIV. Birth outcomes were also collected. The association of HIV-exposure and cART timing on outcomes was assessed by multivariable logistic regression. The independent role of IA was determined by mediation analysis.

MAIN OUTCOME MEASURES

PTB (<37 weeks) and SGA.

RESULTS

There were 38 fetal deaths and 1230 singleton live births. Maternal HIV infection was associated with PTB [adjusted odds ratio (AOR) 1.60, 95% confidence interval (CI) 1.11-2.32] and to a lesser extent SGA (AOR 1.29, 95% CI 0.98-1.70). Maternal cART timing impacted these associations, with highest risk in women who started cART after conception (PTB AOR 1.77, 95% CI 1.09-2.87, SGA AOR 1.52, 95% CI 1.04-2.22). Maternal IA was not associated with PTB independent of HIV infection.

CONCLUSIONS

HIV is associated with PTB. Risk of PTB and SGA was highest in women with HIV who started cART in pregnancy, a modifiable risk factor.