Abnormal circadian blood pressure regulation in children born preterm

Objective To assess a possible relationship between prematurity and casual blood pressure (BP) by means of 24-hour ambulatory BP monitoring (ABPM). Study design ABPM was performed in 41 children aged 5 to 17 years who were born prematurely with (n = 11) or without intrauterine growth restriction, and in 27 matched children who were born at term with a birth weight appropriate for gestational age. Results,Although BP did not differ between the preterm group and control subjects during the daytime, nocturnal standardized systolic BP was elevated (P <.05) and a lack of nocturnal decrease was more prevalent in the preterm children compared with the control subjects (73% versus 41%, P =.01). The difference was caused by a marked increase of nighttime systolic BP in die light-for-date children (1.17 +/- 0.61 standard deviation scores; P <.01), although preterm children with appropriate weight (0.33 +/- 1.00) were not different from control subjects (0.09 +/- 0.73). Nighttime BP standard deviation scores were closely correlated with standardized heart rate, compatible with a role of sympathetic hyperactivation. Conclusion Subtle abnormalities of BP regulation, indicated by a selective-increase of nocturnal systolic BP, are present during childhood in subjects born prematurely, and are prominent in those with intrauterine growth restriction.