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

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.

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.

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.