title: Components of height and blood pressure in childhood.
abstract: BACKGROUND
  In children being taller is associated with higher blood pressure (BP), but few studies have divided height into its components: trunk and leg length. We examined the associations of total height, trunk length and leg length with systolic BP (SBP), diastolic BP (DBP) and pulse pressure (PP) at early childhood and mid-childhood visits, as well as change between the two visits.
  
  
  METHODS
  We obtained five measures of SBP and DBP at the early childhood visit (N = 1153, follow-up rate = 54%) and at the mid-childhood visit (N = 1086, follow-up rate = 51%) respectively, in Project Viva, a US cohort study. We measured total height and sitting height (a measure of trunk length that includes head and neck) and calculated leg length as the difference between the two. Using mixed models, we adjusted the cross-sectional analyses for leg length when trunk length was the exposure of interest, and vice versa. We also adjusted for maternal race/ethnicity, child age, sex, overall adiposity and BP measurement conditions.
  
  
  RESULTS
  At the mid-childhood visit, total height was positively associated with SBP [0.34 (0.24; 0.45) mmHg/cm] but not with DBP [0.07 (-0.003; 0.15)]. In models examining trunk and leg length separately, each was positively associated with SBP [0.72 (0.52; 0.92) and 0.33 (0.16; 0.49) respectively]. In a fully adjusted model with both leg and trunk length, only trunk length remained associated with BP. For a given leg length, a 1-cm increment in trunk length was associated with a 0.63-mmHg (0.42; 0.83) higher SBP and a 0.17-mmHg (0.02; 0.31) higher DBP. For a given trunk length, however, the associations of leg length with SBP [0.13 (-0.03; 0.30)] and with DBP [0.002 (-0.11; 0.12)] were null. These patterns were similar at the early childhood visit.
  
  
  CONCLUSIONS
  Children with greater trunk lengths have higher BPs, perhaps because of the additional pressure needed to overcome gravity to perfuse the brain.
authors.affiliation: Obesity Prevention Program, Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA, MRC Epidemiology Unit, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK, Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL, USA and Department of Nutrition, Harvard School of Public Health, Boston, MA, USA.
authors.forename: Nolwenn
authors.initials: N
authors.lastname: Regnault
authors.forename: Ken P
authors.initials: KP
authors.lastname: Kleinman
authors.forename: Sheryl L
authors.initials: SL
authors.lastname: Rifas-Shiman
authors.forename: Claudia
authors.initials: C
authors.lastname: Langenberg
authors.forename: Steven E
authors.initials: SE
authors.lastname: Lipshultz
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Gillman
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D001827:Body Height / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003971:Diastole / Q000502:physiology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000209:etiology / Q000503:physiopathology; D007866:Leg / Q000033:anatomy & histology / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011674:Pulse; D012307:Risk Factors; D013599:Systole / Q000502:physiology
keywords: Leg length; blood pressure; child; longitudinal studies; trunk length