Early and Later Gestation Outcomes: Competing Risks Across the Pregnancy Continuum

Associations between HIV, antiretroviral therapy and preterm birth in the US Women's Interagency HIV Study, 1995-2018: a prospective cohort

OBJECTIVE

To evaluate the associations of HIV infection with preterm birth (PTB), and of HIV antiretroviral therapy (ART) with PTB.

METHODS

We analysed singleton live-born pregnancies among women from 1995 to 2019 in the Women's Interagency HIV Study, a prospective cohort of US women with, or at risk for, HIV. The primary exposures were HIV status and ART use before delivery [none, monotherapy or dual therapy, or highly active antiretroviral therapy (HAART)]. The primary outcome was PTB < 34 weeks, and, secondarily, < 28 and < 37 weeks. We analysed self-reported birth data, and separately modelled the associations between HIV and PTB, and between ART and PTB, among women with HIV. We used modified Poisson regression, and adjusted for age, race, parity, tobacco use and delivery year, and, when modelling the impact of ART, duration from HIV diagnosis to delivery, nadir CD4 count, and pre-pregnancy viral load and CD4 count.

RESULTS

We analysed 488 singleton deliveries (56% exposed to HIV) to 383 women. The risk of PTB < 34 weeks was similar among women with and without HIV, but the risk of PTB < 37 weeks was higher [32% vs. 23%; adjusted risk ratio (aRR) = 1.43; 95% confidence interval (CI): 1.07-1.91] among women with HIV. The risk of PTB < 34 weeks was lower among women with HIV receiving HAART than among those receiving no ART (7% vs. 26%; aRR:0.19; 95% CI: 0.08-0.44). The associations between HAART and PTB < 28 and < 37 weeks were similar.

CONCLUSIONS

Antiretroviral therapy exposure was associated with a decreased risk of PTB among a US cohort of women with HIV. Given the growing concerns about ART and adverse pregnancy outcomes, this finding that ART may be protective for PTB is reassuring.

Subclinical and clinical chorioamnionitis, fetal vasculitis, and risk for preterm birth: A cohort study

OBJECTIVE

To evaluate the association between subclinical and clinical chorioamnionitis and risk of preterm birth (PTB).

METHODS

Demographic and clinical characteristics were abstracted from medical records and placental examinations performed (N = 1371 pregnancies including spontaneous and medically-indicated PTBs). Pregnancies were classified as having clinical chorioamnionitis (with or without histologic chorioamnionitis), subclinical chorioamnionitis (histologic, but not clinical, chorioamnionitis), or no chorioamnionitis; pregnancies with histologic chorioamnionitis were further evaluated for fetal vasculitis. Relative risks for PTB, early and late PTB, and PTB ± premature rupture of membranes (PROM) were adjusted for maternal characteristics.

RESULTS

Clinical (4.3%) and subclinical (24.5%) chorioamnionitis were not associated with PTB overall. In pregnancies without clinical or subclinical chorioamnionitis, the risk of PTB with PROM and early PTB was 2.2% and 8.6%, respectively. In comparison, clinical chorioamnionitis was associated with an increased risk of PTB with PROM (aRR: 3.42 (95%CI: 1.07, 10.98), whereas subclinical chorioamnionitis was associated with increased risk of PTB with PROM (aRR: 3.92 (95% CI: 2.15, 7.12)) and early PTB (aRR: 1.77 (95% CI: 1.18, 2.64)). Histologic chorioamnionitis with fetal vasculitis was associated with increased risk of PTB with PROM (aRR: 7.44 (95% CI: 3.68, 15.05)) and early PTB (aRR: 2.94 (95% CI: 1.78, 4.87)), whereas histologic chorioamnionitis without fetal vasculitis was associated with increased risk of PTB with PROM only (aRR: 2.64, 95% CI: 1.27, 5.50).

CONCLUSIONS

Subclinical chorioamnionitis and histologic chorioamnionitis with fetal vasculitis were associated with early PTB and PTB with PROM but not with PTB overall, likely due to inclusion of indicated PTBs.