Risk of hypertension into adulthood in persons born prematurely: A national cohort study

Aims: Preterm birth has been associated with elevated blood pressure early in life; however, hypertension risks from childhood into adulthood remain unclear. We conducted a large population-based study to examine gestational age at birth in relation to hypertension risks from childhood into adulthood. Methods and results: A national cohort study was conducted of all 4 193 069 singleton live births in Sweden during 1973-2014, who were followed up for hypertension identified from nationwide inpatient and outpatient (specialty and primary care) diagnoses from any health care encounters through 2015 (maximum age 43 years; median 22.5). Cox regression was used to examine gestational age at birth in relation to hypertension risk while adjusting for other perinatal and maternal factors, and co-sibling analyses assessed the potential influence of unmeasured shared familial (genetic and/or environmental) factors. In 86.8 million person-years of follow-up, 62 424 (1.5%) persons were identified with hypertension (median age 29.8 years at diagnosis). Adjusted hazard ratios for new-onset hypertension at ages 18-29 years associated with preterm (<37 weeks) and extremely preterm (22-27 weeks) birth were 1.28 [95% confidence interval (CI), 1.21-1.36] and 2.45 (1.82-3.31), respectively, and at ages 30-43 years were 1.25 (1.18-1.31) and 1.68 (1.12-2.53), respectively, compared with full-Term birth (39-41 weeks). These associations affected males and females similarly and appeared substantially related to shared genetic or environmental factors in families. Conclusions: In this large national cohort, preterm birth was associated with increased risk of hypertension into early adulthood. Persons born prematurely may need early preventive evaluation and long-Term monitoring for the development of hypertension.