Association between Abortion and All-Cause and Cause-Specific Premature Mortality: A Prospective Cohort Study from the UK Biobank

Abstract

Background: Concerns have been raised about the increasing prevalence of both spontaneous and induced abortions worldwide, yet their effect on premature mortality remains poorly understood. We aimed to examine the associations between abortion and all-cause and cause-specific premature mortality, and the potential effect modification by maternal characteristics. Methods: Women aged 39 to 71 years at baseline (2006 to 2010) with prior pregnancies were derived from the UK Biobank and categorized as no abortion history, spontaneous abortion alone, induced abortion alone, and both spontaneous and induced abortions. All-cause and cause-specific mortality were ascertained through linkage to death certificate data, with premature death defined as occurring before the age of 70. Results: Of the 225,049 ever gravid women, 43,418 (19.3%) reported spontaneous abortion alone, 27,135 (12.1%) reported induced abortion alone, and 10,448 (4.6%) reported both spontaneous and induced abortions. During a median of 14.4 years of follow-up, 5,353 deaths were recorded, including 3,314 cancer-related and 1,444 cardiovascular deaths. Compared with no abortion history, spontaneous abortion alone was associated with an increased risk of all-cause premature mortality (adjusted hazard ratio [aHR] 1.10, 95% confidence interval [CI] 1.02 to 1.17), and induced abortion alone was associated with increased risks of all-cause (aHR 1.12, 95% CI 1.04 to 1.22) and cardiovascular mortality (aHR 1.27, 95% CI 1.09 to 1.48). The aHRs for all-cause and cardiovascular mortality were higher for recurrent abortions, whether spontaneous or induced ( P trend < 0.05). The increased risk of all-cause mortality associated with induced abortion was higher in women with hypertensive disorders of pregnancy than in those without (40% vs. 9%, P interaction = 0.045). Conclusions: Either spontaneous or induced abortion alone was associated with an increased risk of premature mortality, with induced abortion alone particularly linked to cardiovascular death. Future studies are encouraged to explore the underlying mechanisms.