Gestational Age at Birth and Mortality in Young Adulthood EDITORIAL COMMENT
Forskningsoutput: Tidskriftsbidrag › Debate/Note/Editorial
Preterm birth is associated with increased rates of neonatal and infant mortality. It has been hypothesized that gestational age at birth may also be associated with increased mortality rates in adulthood, but to date, no studies have demonstrated this relationship. This national cohort study investigated the association between gestational age at birth and mortality in young adulthood. Data obtained from the Swedish Birth Registry identified 678,528 individuals who were born as singletons between 1973 and 1979 and survived to age 1 year. Among this cohort, 674,820 were included in the final analysis. Of these, 27,979 (4.1%) born preterm (<37 weeks) were followed to age 29 to 36 years (up to 2008). The primary study outcome measures were all-cause and cause-specific mortality. Cox proportional hazards regression was used to estimate the association between gestational age at birth and mortality for 4 age categories: early childhood (age, 1-5 years), late childhood (age, 6-12 years), adolescence (age, 13-17 years), and young adulthood (age, 18-36 years). There were 7095 deaths reported in 20.8 million person-years of follow-up. A strong inverse association was found between gestational age at birth for 2 of the age categories and mortality among individuals still alive at the beginning of each age range. The adjusted hazard ratio [aHR] for each additional week of gestation in early childhood was 0.92 (95% confidence interval [CI], 0.89-0.94; P < 0.001). This inverse association disappeared in late childhood (aHR, 0.99; 95% CI, 0.95-1.03; P = 0.61) and adolescence (aHR, 0.99; 95% CI, 0.95-1.03; P = 0.64), and reappeared in young adulthood (aHR, 0.96; 95% CI, 0.94-0.97; P < 0.001). In young adulthood, the gestational age at birth was associated with mortality rates (per 1000 person-years) as follows: the aHR was 0.94 for 22 to 27 weeks, 0.86 for 28 to 33 weeks, 0.65 for 34 to 36 weeks, 0.46 for 37 to 42 weeks (full-term), and 0.54 for 43 or more weeks (P < 0.001 for all). Relative to individuals born full-term, preterm birth was associated with increased mortality in young adulthood even among individuals born late preterm (34-36 weeks); the aHR was 1.31, with a 95% CI of 1.13-1.50; P < 0.001). Moreover, gestational age at birth in young adulthood had the strongest inverse association with mortality from congenital anomalies, as well as respiratory, endocrine, and cardiovascular disorders, and it had no association with mortality from neurological disorders, cancer, or injury.