Maternal STIs Increase the Risk of Preterm Birth

Premature birth is the world’s leading cause of neonatal morbidity and mortality. Approximately 10% of births in the US are considered “preterm,” which is defined as a birth that occurs before the completion of 37 weeks of gestation.

According to the National Vital Statistics System (NVSS), preterm births have also increased in the last few years, requiring increased attention to practices that help prevent preterm birth. Paralleling the rise in preterm births in an increase in sexually transmitted infections (STIs). Maternal STIs are known to adversely affect growing fetuses, so one study endeavored to explore whether STI-positive pregnant women were more likely to give birth prematurely.

Published in JAMA Network Open, the population-based retrospective cohort study parsed birth certificate data from the NVSS between 2016-2019. All mothers who had a live birth, available STI information, and gestational age at birth were included in the study.

Using the best estimate of gestational at the time of delivery, the investigators subdivided the preterm births by extremely preterm birth (<28 weeks of gestation), very preterm birth (28-31weeks of gestation), and moderately preterm birth (32-36 weeks of gestation).

The study included 14373023 prospective mothers; the average age was 29 years. The ethnicities of the women were 23.9% Hispanic, 6.3% non-Hispanic Asian, 14.3% non-Hispanic Black, and 51.4% non-Hispanic white. Among the mothers in the study population, 1.9% had chlamydia, 0.3% had gonorrhea, and 0.1% had syphilis.

Notably, higher rates of chlamydia, gonorrhea, and syphilis were found in women younger than 25 years old, non-Hispanic Black women (as compared to non-Hispanic white women), women with less education (versus above a high school education), women who were unmarried, women who smoked during their pregnancy, and women who needed Medicaid (versus women with private insurance).

Among all the newborns, 8.0% were preterm births (n=1146800). The rate of preterm birth was 9.9% among women with chlamydia, 12.2% for women with gonorrhea, and 13.3% for women with syphilis.

These results were then adjusted for age, race and ethnicity, education, marital status, parity, previous history of preterm birth, pre-pregnancy body mass index, pre-pregnancy diabetes, pre-pregnancy hypertension, smoking during pregnancy, initiation of prenatal care, insurance type, other infections during pregnancy, and infant sex.

All 3 STIs monitored in this study were significantly correlated with moderately preterm birth. There were also significant associations of gonorrhea and syphilis with very preterm birth.

Overall, the associations between chlamydia, gonorrhea, and syphilis and preterm birth were statistically significant, and remained relatively consistent across age, race, and ethnicity. The investigators concluded that their findings supported the US Centers for Disease Control and Prevention (CDC) recommendation to screen and treat these STIs in pregnant women.