Association of blood pressure in adolescence with birthweight.

AIMS To compare the blood pressure of very low birthweight infants with that of normal birthweight controls in adolescence. METHODS A cohort of all infants of birthweight < or = 1500 g born to women resident in the county of Merseyside in 1980-1 was followed up at age 15 years with age, sex, and school matched controls. Growth indices and blood pressures were measured under standard conditions. The smoking history of mothers and children and their status for several socioeconomic variables were documented. In a matched pairs analysis systolic and diastolic blood pressures were compared for cases and controls before and after adjusting for height, weight, and body mass index. RESULTS There were 172 singleton 15 year old survivors of birthweight < 1500 g out of 40,321 live births of Merseyside residents in 1980-1. Of the 172 survivors, 128 (74%) who had no clinical disability and 11 (6%) with a clinical disability but attending normal schools, were assessed with individually matched age, sex, and school controls. Twenty three (13%) had a clinical disability and were attending special schools; these were assessed without controls. Ten (6%) children refused or were unavailable for assessment. The systolic blood pressure was significantly higher in cases than in controls; the mean of the difference was 3.2 mm Hg. The diastolic blood pressure was also higher in the cases, but the difference was not significant. The controls were significantly heavier (4.4 kg), taller (4.0 cm), with larger head circumference (1.5 cm) than the cases. The difference in body mass index was not significant. Adjusting for height, weight, or body mass index increased the difference in systolic blood pressure between cases and controls. There were no significant differences in the socioeconomic variables, but what differences did exist favoured the controls. There was also a higher prevalence of smoking among the children and the mothers of the cases than the controls. CONCLUSIONS The study supports the hypothesis that in adolescents variation in systolic blood pressure has its origins in fetal development. Some of the variation could be attributed to socioeconomic differences.