Pre-term delivery and long-term risk of heart failure in women: a national cohort and co-sibling study

AIMS: Women who deliver pre-term have higher future risks of hypertension and ischaemic heart disease, but long-term risks of heart failure (HF) are unknown. We examined these risks in a large national cohort. METHODS AND RESULTS: All 2 201 284 women with a singleton delivery in Sweden during 1973-2015 were followed up for inpatient or outpatient HF diagnoses through 2015. Cox regression was used to compute hazard ratios (HRs) for HF associated with pregnancy duration, adjusting for other maternal factors. Co-sibling analyses assessed for confounding by shared familial (genetic and/or environmental) factors. In 48.2 million person-years of follow-up, 19 922 women were diagnosed with HF (median age: 60.7 years). Within 10 years after delivery, the adjusted HR was 2.96 [95% confidence interval (CI): 2.48-3.53] for HF associated with pre-term (gestational age: <37 weeks) compared with full-term (39-41 weeks) delivery. Stratified HRs were 4.27 (2.54-7.17) for extremely pre-term (22-27 weeks), 3.39 (2.57-4.48) for moderately pre-term (28-33 weeks), 2.70 (2.19-3.32) for late pre-term (34-36 weeks), and 1.70 (1.45-1.98) for early term (37-38 weeks). These HRs declined but remained elevated at 10-19 years (pre-term vs. full term: HR: 2.19; 95% CI: 1.94-2.46), 20-29 years (1.80; 1.67-1.95), and 30-43 years (1.56; 1.47-1.66) after delivery, and were not explained by shared familial factors. CONCLUSION: Pre-term and early term delivery were associated with markedly increased future hazards for HF, which persisted after adjusting for other maternal and familial factors and remained elevated 40 years later. Pre-term and early-term delivery should be recognized as risk factors for HF across the life course. KEY QUESTION: What are the long-term hazards for heart failure (HF) across the life course in women who deliver preterm? KEY FINDING: Preterm and early term delivery were associated with ∼3- and 1.7-fold adjusted hazards for HF in the next 10 years vs. full-term delivery. These hazards declined but remained elevated 40 years later, and were not explained by shared familial factors. TAKE HOME MESSAGE: Preterm and early term delivery were associated with increased future hazards for HF, which persisted for 40 years after adjusting for other maternal and familial factors. Preterm and early term delivery should be recognized as lifelong risk factors for HF.