Introduction
Fear of childbirth (FOC) is a common obstetrical challenge that complicates about every 10th pregnancy. Background factors of FOC are diverse. We evaluated the association of induced abortion (IA) and FOC in subsequent pregnancy.

Material and methods
Population-based register study based on three Finnish national registers: the Register of Induced Abortions, the Medical Birth Register and the Hospital Discharge Register. The study cases were primigravid women undergoing an IA in 2000–2015 and subsequent pregnancy ending in live singleton birth up to 2017. Each case had three controls, matched by age and residential area, whose first pregnancy ended in a live birth. The main outcome was the incidence of FOC in the subsequent pregnancy. In a secondary analysis, we assessed other risk factors for FOC.

Results
The study cohort consisted of 21 455 women and 63 425 controls. Altogether, 4.2% of women had a diagnosis of FOC. The incidence was higher in women with a history of IA than in controls (5.6% vs 3.7%, P < 0.001). A history of IA was associated with higher odds for FOC: adjusted odds ratio [aOR] 1.20 with 95% confidence interval (CI) 1.11–1.30. In addition, a history of psychiatric diagnosis (aOR 3.48, 95% CI 3.15–3.83), high maternal age, 30–39 years old (aOR 1.55, 95% CI 1.43–1.67; P < 0.001) and ≥40 years old (aOR 3.00, 95% CI 2.37–3.77; P < 0.001) and smoking (aOR 1.20, 95% CI 1.11–1.31; P < 0.001) were associated with increased odds for FOC. Women living in densely populated or rural areas and those with lower socioeconomic class had lower odds for FOC.

Conclusions
A history of IA is associated with increased odds for FOC in subsequent pregnancy. However, the associations of FOC with a history of psychiatric diagnosis and elevated maternal age (especially ≥40 years old) are more pronounced.