The Burden of Maternal Syphilis: National Trends and Associated Pregnancy Outcomes in the United States.

Background: Maternal syphilis is on the rise in the United States, posing a substantial public health concern. Caused by Treponema pallidum subspecies pallidum, syphilis can be transmitted sexually or vertically during pregnancy. This study provides the United States' national estimates on the prevalence, correlates, and outcomes of maternal syphilis.

Method: Using the Nationwide Inpatient Sample (NIS: 2016-2021), we analyzed maternal syphilis-associated pregnancy hospitalizations among women aged 13 to 49 years in the United States. We examined demographic, behavioral, hospital, and clinical characteristics associated with maternal syphilis. Joinpoint regression was used to describe the annual average percent change (AAPC) of these hospitalizations. Survey logistic regression assessed the association between maternal syphilis and pregnancy outcomes across different racial groups.

Results: Out of 23 551 491 pregnancy-related hospitalizations during the study period, 23 080 involved maternal syphilis. Pregnant women, who used alcohol, tobacco, cannabis, and opioids, as well as those with conditions such as bipolar disorder, HIV/AIDS, anxiety, depression, and obesity, were at increased risk of maternal syphilis. The overall prevalence of maternal syphilis during the study period is high for Native American and Black pregnant women. However, the average annual increment is notably higher among Native American women followed by White women. Adjusting for demographic, behavioral, and clinical confounders, women with maternal syphilis had a higher risk of preeclampsia, severe maternal morbidity, prolonged hospital stay, preterm birth, and intrauterine fetal demise.

Conclusion: The significant increase in maternal syphilis across all racial groups underscores the need for increased awareness, screening, and treatment efforts to mitigate its adverse impact on pregnancy and other health outcomes.