Pregnancy Among Reported Lyme Disease Cases—United States, 1992–2019

ABSTRACT Background Lyme disease (LD), the most common vector‐borne disease in the United States, typically presents with a localised erythema migrans rash (EM). Left untreated, infection can disseminate to cause severe heart, joint or nervous system manifestations. Summaries of LD surveillance data have been published previously but did not include the frequency, demographic or clinical characteristics of LD cases during pregnancy. Methods We summarised confirmed and probable LD cases by pregnancy status as reported to the U.S. Centers for Disease Control and Prevention during 1992–2019. We defined an LD case during pregnancy as one with (1) female sex, (2) age 14–49 years and (3) positive pregnancy indication. We evaluated the frequency, seasonality, age distribution, race and ethnicity, geographic distribution and clinical manifestations of LD cases during pregnancy and cases among non‐pregnant females. We compared proportions using chi‐squared tests. Results Among 698,876 reported LD cases, 112,002 (16%) were confirmed or probable cases among females aged 14–49 years; 32,301 (29%) were specifically reported as non‐pregnant and 643 (0.6%) (568 confirmed and 75 probable cases) reported as pregnant. Illness onset peaked in June among LD cases during pregnancy, but in July for cases among non‐pregnant females. A higher proportion of confirmed LD cases during pregnancy had only EM rash than did cases among non‐pregnant females (66% vs. 60%, p = 0.019). Conclusions LD cases during pregnancy are rare. Compared to non‐pregnant females, cases among pregnant females more commonly involve early clinical manifestations. These patterns could suggest earlier detection or more complete reporting of LD cases during pregnancy than their non‐pregnant counterparts. Earlier detection could be due to frequent contact with healthcare or increased self‐advocacy during pregnancy. Prompt antimicrobial treatment is critical for preventing severe disease and reducing risk of adverse pregnancy or birth outcomes.