Antiretroviral therapy for HIV not associated with higher risk for preterm birth

After studying births from women with and without HIV and using and not using antiretroviral therapy (ART), there seems to be no increased risk for preterm birth when using ART, according to a paper published in HIV Medicine.

Investigators from around the United States analyzed the deliveries of 488 babies among 383 women between 1995 and 2019 in order to evaluate the relationship between HIV infection with preterm birth, and of HIV ART with preterm birth.

The study authors noted that ART during pregnancy can virtually eliminate the passing of HIV from mother to child and can improve survival for women with HIV. However, despite this data, HIV without ART during pregnancy can increase risk for preterm birth, produce low infant birthweight, and still birth. Research conducted in what the study authors called low- and middle-income countries found that ART increases the risk of preterm birth. Other US-based analyses did not find a higher risk for preterm birth with ART.

In this study, women who gave birth to singletons after 20 weeks were analyzed for self-reported preterm birth less than 34 weeks, but the investigators also noted preterm birth less than 28 and 37 weeks as secondary outcomes.

Of approximately 5000 women included in the analysis, about three-quarters were women with HIV, the study authors said. Of those with HIV, about 1000 self-reported pregnancy, which resulted in 1893 deliveries. Due to various exclusions such as abortion, miscarriage, or inability to acerating gestational age at birth, the investigators compared 218 women with HIV with 272 deliveries to 165 women without HIV with 216 deliveries for their analysis.

The mean age at delivery for the women with HIV was 40 years, the study authors found, and they also said 62 percent were non-Hispanic black women, a quarter reported tobacco use during pregnancy and the mean pre-pregnancy BMI was 29 kg/m2. For women without HIV, the mean age was 41, the study authors said, with 56 percent being non-Hispanic black, 29 percent reporting tobacco use during pregnancy, with a mean pre-pregnancy BMI of 31 kg/m2.

The study authors learned that 69 percent of deliveries were exposed to highly active ART prior to delivery (a mean duration of 6 years), 14 percent to monotherapy or dual therapy, and 17 percent of women were not on ART. Among deliveries to women on ART during the pregnancy, 64 percent had started ART before pregnancy.

The risk of preterm birth less than 34 weeks was similar among women with and without HIV, the study authors found, at 10 and 8 percent, respectively. Less than 37 weeks was higher among women with HIV when compared to those without HIV (32 vs. 23 percent, respectively) but did not differ for the risk less than 28 weeks, the study authors determined.

The risk for preterm birth among women with HIV was lower when using highly active ART compared with no therapies (7 vs. 26 percent, respectively), and the risk was lower when using mono or dual therapy compared to no therapies, the study authors observed.

“We found that while HIV may be slightly associated with preterm birth, ART was associated with a decreased risk of preterm birth,” the study authors concluded. “Specifically, both highly active ART and monotherapy or dual therapy were associated with a greater than 80 percent reduction in the likelihood of preterm defined as < 34 weeks, and this result held at thresholds of < 28 and < 37 weeks.”

The study authors called this finding reassuring, though noted it requires further study.

The research was originally presented at the Infectious Diseases for Obstetrics and Gynecology (IDSOG) Annual Meeting in August 2020, the authors noted.

By Rachel Lutz