Relationship between birth weight and awake blood pressure in children and adolescents in absence of intrauterine growth retardation.

This study was designed to examine the relationship between birth weight (BW) and ambulatory blood pressure in children and adolescents, born at term in absence of intrauterine growth retardation. Twenty-four hour ambulatory blood pressure monitoring (ABPM) was performed on 332 children (150 boys), aged from 6 to 16 years. Subjects were stratified by BW tertiles and age. ABPM was performed using SpaceLabs 90207 monitor during a regular school day. Blood pressure (BP) was measured every 20 min from 06:00 to 24:00, and thereafter every 30 min. Means of systolic BP (SBP) and diastolic BP (DBP) during 24 h, daytime (08:00 to 22:00), and nighttime (24:00 to 06:00) were calculated. Systolic and diastolic load was estimated as the percentage of measurements above the age- and sex-specific 95th percentile during the 24 h. BW was inversely related to daytime (SBP (P = .04) and SBP load (P = .04) when controlled for sex, current height, ponderal index (weight/height3), and age. The predictive values of daytime SBP throughout the pediatric age group in the two extreme tertiles of BW (lowest, 2.500 to 3.200 kg; and highest, 3.501 to 4.820 kg) were obtained from regression equations including SBP during activity period or SBP load and age. Children who had lower BW tended to have higher daytime SBP or SBP load at any age although this difference was not statistically significant. These differences became more evident as the subjects got older. BW is a determinant of daytime SBP even in the absence of intrauterine growth retardation. The influence of BW seems to increase with age.