Risk of Sexually Transmitted Infections Among Pregnant Persons With Substance Use Diagnoses

Sexually transmitted infections (STIs) in pregnancy have increased among reproductive-aged women and are associated with adverse maternal and infant outcomes. Identifying high-risk groups for perinatal STIs, including those with differential substance use diagnoses, is essential. This study examines the risk of STIs in pregnancy by specific isolated and co-occurring substance use diagnoses.

Data stem from a population-based study of pregnant individuals with liveborn, singleton deliveries in California from 2011 to 2021. Birth certificates were linked to maternal and infant hospital records, and maternal STIs and substance diagnoses were identified with the International Classification of Diseases (ICD) revision 9 and 10 codes. Modified Poisson regressions with robust error variance estimated the unadjusted and adjusted risk of each STI (chlamydia, gonorrhea, and syphilis) among those with each substance diagnosis (alcohol, tobacco, cannabis, cocaine, stimulants, opioids, and sedatives). Risk was estimated for isolated and comorbid substance diagnoses.

Among 4,481,096 pregnant individuals, 31,123 (0.7%) had chlamydia, 4132 (0.1%) had gonorrhea, and 7267 (0.2%) had syphilis. All substance diagnoses were associated with increased risk of STIs. In adjusted models, both isolated and comorbid stimulant diagnoses were associated with some of the highest risk of chlamydia (adjusted risk ratio [aRR] = 3.11-3.63), gonorrhea (aRR = 7.11-9.84), and syphilis (aRR = 13.12-14.30). Generally, those with comorbid substance diagnoses had higher risk of each STI than their counterparts with isolated diagnoses.

Those with substance diagnoses, particularly stimulant and/or co-occurring diagnoses, are at elevated risk for STIs in pregnancy. There remains unmet need for prevention, screening, and treatment to address STIs in pregnancy among those with substance use.