- Studies have found that people with HIV are at increased risk for giving birth prematurely
- Researchers in British Columbia analyzed 25 years of data on pregnancy in people with HIV
- Sexually transmitted infections or bacterial vaginosis during pregnancy doubled the prematurity risk
When used as directed, HIV treatment (antiretroviral therapy; ART) is highly effective at suppressing the virus and helping the immune system largely repair itself. These changes caused by ART have resulted in improved health and near-normal life expectancy for many people with HIV. What’s more, having a suppressed viral load due to ART significantly reduces the risk of infants acquiring HIV in pregnancy and during the birthing process.
Studies have found that, in general, pregnant people with HIV are at increased risk for having preterm births. Infants born prematurely tend to be born underweight and are at increased risk for complications.
To find out which factors increase the risk of premature birth in pregnant people with HIV, a team of researchers in British Columbia analyzed health-related information collected from pregnant people with HIV and their infants between 1997 and 2022. The researchers focused on 578 pregnancies in which only one infant was born (referred to as “singleton pregnancies” by the team). Overall, 93% of people were on ART prior to giving birth, and 80% of people on ART had a suppressed viral load at the time they gave birth.
The researchers found that 11% of participants had either a sexually transmitted infection (STI) or bacterial vaginosis (BV) during pregnancy. A total of 111 babies (19%) were born prematurely.
The researchers analyzed their database to find which factors were statistically linked to an increased risk for giving birth prematurely. Their analysis considered many issues—ethnicity, history of preterm birth, substance use before and around the time of birth, coinfection with hepatitis C virus, use of protease inhibitor–based ART, and CD4+ cell count and viral load at time of birth.
They found that the presence of STIs or bacterial vaginosis significantly increased the risk of premature birth among people with HIV. In effect, having an STI or BV during pregnancy doubled the risk of giving birth prematurely. For instance, among participants with an STI or BV during pregnancy, 37% subsequently gave birth prematurely. Among participants without an STI or BV, 17% gave birth prematurely.
Bear in mind
Over the course of 25 years of data collection with pregnant people with HIV in British Columbia, researchers found that, overall, 19% of infants were born prematurely. In contrast, the overall rate of premature births among the whole population of this province was about 7%.
The researchers drew attention to a specific STI called trichomoniasis (commonly called “trich” by healthcare providers). This STI, which is caused by a parasite (Trichomonas vaginalis), can be treated. The B.C. researchers stated that people who had trich during pregnancy “had a preterm birth rate of 50%.” However, the number of people with trich during pregnancy was relatively small, so a meaningful statistical analysis could not be done. The presence of this STI may be an issue that future studies can address.
The long duration—25 years of data collection—is an important strength of the present study. However, the researchers are not sure what proportion of people were not screened for STIs and BV during pregnancy. The researchers stated that other studies have found relatively high rates of BV in people with HIV. However, in the present study, they noted that “only 7.3% of pregnant people with HIV in our population were identified with bacterial vaginosis.” The researchers added: “The Society of Obstetricians and Gynaecologists of Canada does not recommend routine screening for bacterial vaginosis in pregnancy for [symptom-free] individuals without risk factors for preterm birth. Testing is only recommended for pregnant people with symptomatic bacterial vaginosis.”
Nevertheless, the study’s findings underscore the need for comprehensive screening for STIs and bacterial vaginosis in pregnant people with HIV.
—Sean R. Hosein
Resources
Sexually transmitted and blood-borne infections: Guides for health professionals – Public Health Agency of Canada
STI-associated syndromes guide: Syndromic management – Public Health Agency of Canada
REFERENCES:
- Wong JMH, Av-Gay G, Lee T, et al. Sexually transmitted infections and bacterial vaginosis and preterm birth in pregnant people living with HIV: a population-based cohort study. International Journal of STD and AIDS. 2025 Aug;36(9):712-718.
- Ravindran J, Richardson BA, Kinuthia J, et al. Chlamydia, gonorrhea, and incident HIV infection during pregnancy predict preterm birth despite treatment. Journal of Infectious Diseases. 2021 Dec 15;224(12):2085-2093.
- Walters MK, Bulterys MA, Barry M, et al. Probability of vertical HIV transmission: a systematic review and meta-regression. Lancet HIV. 2025 Sep;12(9):e638-e648.