IntroductionEctopic pregnancy leads to reproductive health morbidity, including greater risk of another ectopic pregnancy, infertility, and, in rare cases, mortality. Information on trends in the incidence of ectopic pregnancy in the last decade is limited. MethodsA population-based cross-sectional study of women aged 15-44 years enrolled at Kaiser Permanente Northern and Southern California 2010-2019 was conducted. Electronic health records were used to identify ectopic pregnancies. The crude ectopic pregnancy incidence per 1000 pregnancies (live births, induced abortions, and ectopic pregnancies) and 95% confidence interval (CI) was estimated per study year, overall, and stratified by age group. The age-adjusted incidence and 95% CI was estimated per study year, overall, and stratified by race/ethnicity. Temporal trend was assessed using Poisson regression. ResultsThere were 15,537 ectopic pregnancies among 979,027 pregnancies. The overall age-adjusted ectopic pregnancy incidence was 15.8 per 1000 pregnancies, 95% CI: 15.6, 16.1. The annual incidence increased from 15.2, 95% CI: 14.4, 16.1, in 2010 to 16.4, 95% CI: 15.6, 17.2, in 2019 (p < 0.001). The overall incidence was highest among women aged 40-44 years (24.2, 95% CI: 22.7, 25.6) and non-Hispanic Black women (21.9, 95% CI: 21.0, 22.8); compared to 30-34-year-old (16.2, 95% CI: 15.7, 16.6) and non-Hispanic White (14.6, 95% CI: 14.1, 15.0) women, respectively. DiscussionThe increase in ectopic pregnancy incidence during the studied period was largely driven by increasing incidence in younger women. However, disparities in the incidence by age and race/ethnicity persisted. ConclusionEctopic pregnancy remains a significant source of reproductive health morbidity, especially for older ( >40 years) and non-Hispanic Black women.