Objective: We investigated the association between diagnosed maternal sexually transmitted infections (STIs) and very preterm or late preterm birth in 108,346 South Carolina women receiving medical care purchased by Medicaid from 1996 through 2002, and delivering singleton infants.
Methods: ICD9 codes in South Carolina Medicaid data were used to identify maternal infections. Gestational age was obtained from birth certificates.
Results: Trichomoniasis, gonorrhea, and/or Chlamydia/non-gonococcal urethritis (NGU) were diagnosed in 4,208 women. Preterm birth occurred in just over 9% of pregnancies. Women diagnosed with one of the infections in the first 7 months of pregnancy were significantly more likely to deliver very preterm infants (adjusted HR = 1.73, p < 0.0001). Women with infection in the first 8 months were significantly more likely to deliver between 33 and 36 weeks (adjusted HR = 1.39, p < 0.0001). Of the three infections, Chlamydia/NGU was most strongly associated with preterm birth and infections occurring later in pregnancy (months 6, 7, and 8).
Conclusion: STIs appear to be preventable risk factors for very and late preterm birth.