Could Vaginal Swab Predict Preterm Birth?

— Point-of-care diagnostic in the works

MedicalToday

Measuring concentrations of certain biomarkers in vaginal secretions may provide a way to assess risk of preterm birth, researchers found.

Levels of tissue inhibitor of matrix metalloproteinases (TIMP-1), a protein that may play a role in pregnancy, and D-lactic acid in a woman's vaginal secretion could possibly determine if a woman was at risk of preterm birth due to a short cervix, reported Larry Forney, PhD, of the University of Idaho in Moscow, and colleagues.

While both short cervical length and certain Lactobacillus species in the microbiome are risk factors for preterm birth, in certain parts of the developing world, technology to test for both of these is unavailable, they wrote in , an open-access journal of the American Society for Microbiology.

"There is a need to have a cost-effective diagnostic that can be used to identify women who are at risk for a preterm birth, so more intensive monitoring and, if needed, the most appropriate therapies can be initiated," Forney said in a statement. "The goal is to have a point-of-care diagnostic that people can use in a clinic that doesn't require any advanced technology, expensive instrumentation, or extremely specialized skills."

The authors said that in the U.S., a transvaginal ultrasound can be performed to determine cervical length at 18 to 24 weeks gestation, and women with a short cervix can either be treated with progesterone, a cervical cerclage, or cervical pessary to reduce risk of premature delivery, or antibiotics for bacterial vaginosis, which can "attempt to restore the dominance of lactobacilli."

They also noted the role of potential biomarkers in helping to assess risk for preterm birth, writing "the level of D-lactic acid in the vagina may indicate which bacterial species are dominant." The authors also cited previous research on TIMP-1, which may play a role in early stages of pregnancy, and has played a role in preterm labor in pre-clinical studies.

The researchers examined data from 340 women, with a mean age of about 29, and a mean BMI of about 28. Mean cervical length was 32.9 mm, and about 11% of women had a short cervix. Cervical length and vaginal samples were collected at about a mean gestational age of 22 weeks, with a mean gestational age at delivery of 38 weeks. About 17% of women had preterm birth (defined as before 37 weeks gestation).

Researchers found that TIMP-1, D-lactic acid, and another protein, p62, as well as age and race affected cervical length. TIMP-1, p62, and black race had negative effects on cervical length, they stated.

"Measuring levels of TIMP-1 and D-Lactic acid in vaginal secretions might be a straightforward way to assess a woman's risk for preterm birth," Forney noted.

A study limitation was the inability to relate lactic acid and TIMP-1 levels or microbiome composition with pregnancy outcomes.

"Our next step is to do a larger study that includes women in their first trimester so that if the findings are similar, monitoring and possible treatment can begin earlier in gestation," Forney said.

Disclosures

The study was supported by the Bill and Melinda Gates Foundation, the Brazilian Ministry of Health, and the Brazilian National Research Council.

Data collection and analyses were performed by IBEST Genomics Resources Core at the University of Idaho, which is partially supported by a NIH COBRE grant.

Forney and co-authors disclosed no relevant relationships with industry.

Primary Source

mBio

Witkin SS, et al "Vaginal Biomarkers That Predict Cervical Length and Dominant Bacteria in the Vaginal Microbiomes of Pregnant Women" mBio 2019; DOI: 10.1128/mBio.02242-19.