Publication date: Feb 01, 2025

Concomitant use of antiretroviral therapy (ART), hormonal contraception, and isonicotinic acid hydrazide (isoniazid) for tuberculosis prevention is common among women of reproductive age who are living with HIV in sub-Saharan Africa. We estimated the effect of isoniazid on 6-month pregnancy risk among Malawian women living with HIV in the Family Planning and Antiretroviral Therapy (FP-ART) prospective cohort study, overall and among subgroups defined by ART regimen type and hormonal contraceptive method. The analytic sample included visits contributed by participants who were currently using either efavirenz- or dolutegravir-based ART and either depot medroxyprogesterone acetate (DMPA) or levonorgestrel (LNG) implant contraception at the time of the visit. The exposure was self-reported, current isoniazid use (yes/no). The binary outcome measure, 6-month pregnancy, was defined as an estimated conception date 1-183 days after the study visit date. We used a marginal structural linear risk regression model with inverse probability of treatment weights, multiple imputation by chained equations, and bootstrapping to estimate risk differences (RD) and 95% confidence intervals (CI). The analytic sample included 4709 study visits occurring between September 2017 and June 2021. The weighted 6-month pregnancy risk among isoniazid use visits was 3. 0% compared with 2. 3% among non-use visits (RD 0. 7%, 95% CI: -0. 7%, 2. 1%), and the results were qualitatively similar for all subgroup estimates. We did not find a clinically significant effect of isoniazid use on 6-month pregnancy incidence among women concomitantly using ART and either DMPA or LNG implant contraception.

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Original Article