ACTG 5279 BRIEF-TB was a multi-national, open-label noninferiority trial comparing two regimens for latent TB infection among people with HIV.  A planned secondary analysis included participants assigned female at birth in the standard 9-month isoniazid prevention therapy (IPT) arm who became pregnant and had known pregnancy outcome.  This study presents information from 128 participants (39 IPT-exposed, 89 unexposed): 70% were recruited from sub-Saharan Africa; median age and CD4 were 31.5 years and 552 cells/µL at pregnancy outcome.  Compared to unexposed participants, fewer IPT-exposed participants were receiving ART at pregnancy outcome (79% vs. 96%), and the regimen was less likely to include efavirenz at enrollment (23% vs. 33%) and at pregnancy outcome (64% vs. 87%).  All IPT-exposed pregnancies were conceived while taking isoniazid, and a small proportion also had second trimester exposure (relatively few had third trimester exposure).  19/39 (49%) completed IPT while pregnancy was ongoing, 9 (23%) discontinued IPT early, 8 (21%) had a pregnancy outcome while taking IPT, and 3 (8%) had possible early exposure.  35/128 (27%) pregnancies ended in a non-live birth outcome, including 25 spontaneous abortions, 6 induced abortions, 2 stillbirths, and 2 ectopic pregnancies.  Multivariate analyses indicated a nearly 2-fold increased risk of fetal demise with IPT exposure at conception and continuing into at least the first trimester; this effect was attenuated when adjusted for covariates proximal to pregnancy outcome including ART use.  Proportions of preterm delivery and low birth weight were similar between IPT exposed and unexposed participants.