Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. In this large population-based study in the United States, maternal sexually transmitted infections including chlamydia, gonorrhea, and syphilis were associated with an increased risk of preterm birth, especially of moderately and very preterm birth.

2. Based on the results of this study, the authors recommend that pregnant women with sexually transmitted infections before or during pregnancy require targeted therapies to minimize the risk of preterm birth.

Evidence Rating Level: 2 (Good)

Study Rundown:

Maternal infection is a risk factor for preterm birth. Chlamydia, gonorrhea, and syphilis are among the most common sexually transmitted infections (STIs) worldwide. Several studies have examined the pathogenesis and association between STIs and preterm birth at a molecular level, however, their association at an epidemiological and population level is lacking. This retrospective cohort study used US nationwide birth certificate data to examine the association of maternal chlamydia, gonorrhea, and syphilis infections with the risk of preterm birth in more than 14 million mother-infant pairs with singleton live births. The primary endpoint was preterm birth, defined as gestational age less than 37 weeks. In this population-based cohort study with more than 14 million mother-infant pairs, maternal STIs were associated with an increased risk of preterm birth that was statistically significant, especially moderately and very preterm birth. These findings suggested that appropriate preconception and antenatal counselling and prophylactic treatment (if necessary) should be offered to all females of child-bearing age. Furthermore, pregnant women with STIs during pregnancy require targeted therapies to minimize the risk of preterm birth. A limitation of this study was that the national database used for analysis did not provide follow-up information on treatment of STIs, including the status of treatment vs no treatment, resulting in potential confounding in the associations between maternal STIs and preterm birth.

In-Depth [retrospective cohort]:

This population-based retrospective cohort study included 14,373,023 mothers (mean [SD] age, 29 [5.8] years; Hispanic, 3,435,333 [23.9%]; Asian, 912,425 [6.3%]; Black, 2,058,006 [14.3%]; and White, 7,386,568 [51.4%]) and their corresponding birth certificate data from the US National Vital Statistics System between 2016 and 2019. Inclusion criteria included all mothers who had a singleton live birth and available data on chlamydia, gonorrhea, or syphilis infection before or during pregnancy. Overall, 267, 260 (1.9%) mothers had chlamydia, 43,147 (0.3%) had gonorrhea, and 16,321 (0.1%) had syphilis. In total, 1, 146, 800 (8.0%) newborns were born preterm where the rate of preterm birth was 9.9%, 12.2%, and 13.3% among women with chlamydia, gonorrhea, and syphilis infection, respectively. The adjusted odds ratio of preterm birth was 1.03 (95%CI, 1.02-1.04) for chlamydia, 1.11 (95%CI, 1.08-1.15) for gonorrhea, 1.17 (95%CI, 1.11-1.22) for syphilis, and 1.06 (95%CI, 1.05-1.07) for any of these STIs compared to the control group (mothers without STIs).

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