title: Adult men born in spring have lower blood pressure.
abstract: OBJECTIVE
  To determine whether there is a relationship between season of birth and adult blood pressure, as a possible early determinant of later blood pressure.
  
  
  METHODS
  We studied 572 men, aged 45-64 years, whose blood pressure was measured in standardized manner as part of a nation-wide survey in Spain. To analyse the seasonal variation in blood pressure, a linear regression was performed, adjusting for age, height, body mass index, occupation and rural or urban residence.
  
  
  RESULTS
  We found seasonal variation in mean systolic blood pressure, with maxima in adults born in autumn and winter, and minima in those born in spring 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 relationship is compatible with several hypotheses, the difference found between spring and autumn, partially independent of some other factors, might indicate that the extent of early exposure to sunlight is implicated in determining later blood pressure. This needs further investigation.
authors.affiliation: Department of Preventive Medicine, School of Medicine, Universidad Autónoma de Madrid, Spain. joseramon.banegas@uam.es
authors.forename: J R
authors.initials: JR
authors.lastname: Banegas
authors.forename: F
authors.initials: F
authors.lastname: Rodríguez-Artalejo
authors.forename: J J
authors.initials: JJ
authors.lastname: de la Cruz
authors.forename: A
authors.initials: A
authors.lastname: Graciani
authors.forename: F
authors.initials: F
authors.lastname: Villar
authors.forename: J
authors.initials: J
authors.lastname: del Rey-Calero
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D012621:Seasons; D013030:Spain; D013599:Systole / Q000502:physiology