Adult men born in spring have lower blood pressure

Objective To determine whether there is a relationship between season of bi rth and adult blood pressure, as a possible early determinant of later bloo d pressure, Design We studied 572 men, aged 45-64 years, whose blood pressure was measu red in standardized manner as part of a nation-wide survey in Spain, To ana lyse the seasonal variation in blood pressure, a linear regression was perf ormed, adjusting for age, height, body mass index, occupation and rural or urban residence. Results We found seasonal variation in mean systolic blood pressure, with m axima in adults born in autumn and winter, and minima in those born in spri ng and summer. The greatest difference in systolic blood pressure occurred between adults born in spring (134.1 mmHg) and those born in autumn (140.3 mmHg). After adjustment, the difference in means between spring and autumn was 5.9 mmHg (95% confidence interval 0.7 to 11.1 mmHg, P = 0.03), Conclusions This study demonstrated differences in systolic blood pressures of adult men according to the season of their birth, Although this relatio nship is compatible with several hypotheses, the difference found between s pring and autumn, partially independent of some other factors, might indica te that the extent of early exposure to sunlight is implicated in determini ng later blood pressure. This needs further investigation. (C) 2000 Lippinc ott Williams & Wilkins.