Association between adverse childhood experience and unintended pregnancy among Japanese women: a large-scale cross-sectional study.

Unintended pregnancy (UP) can negatively impact the health of mothers, children, and families. While Adverse Childhood Experiences (ACEs) are increasingly known to affect sexual health, the influence on pregnancy intention is not fully understood. This study examines the relationship between ACEs and UP and explores other related factors, using 5049 pregnant and postpartum women data from the Japan COVID-19 and Society Internet Survey (JACSIS). We measured participants' pregnancy intentions, ACEs, family functioning, and social network size. Logistic regression analysis provided odds ratios and 95% confidence intervals (CI). The prevalence of UP was approximately 16.5% (n = 893). Cumulative ACEs were consistently associated with UP, even after adjusting for intermediate variables in adulthood. The odds ratio for UP with a single ACE was 1.00 (CI: 0.82-1.21) but rose significantly with multiple ACEs: 1.39 (CI: 1.10-1.76) with double, 1.38 (CI: 1.02-2.86) with triple, and 1.81 (CI: 1.37-2.39) with more. Additionally, bad family functioning and lack of social networks emerged as contributors to UP. In conclusion, this study showed that ACEs are potentially correlated with UP. A deeper understanding of the transition from childhood experiences to UP is important for health interventions, necessitating further investigation.