Measurement of systolic blood pressure in the follow-up of low birth weight infants.

Systolic blood pressure was measured using the Doppler technique in 149 infants who attended the neonatal follow-up clinic. One hundred and six of these infants were graduates of the neonatal intensive care unit and 81% were prematurely delivered. Most of the participants were examined only once and their postnatal age ranged between 2-191 weeks at the time the blood pressure was measured. During the first weeks of life the blood pressure in infants whose birth weight was > 2000 grams appeared to be higher than that of infants of lower birth weight infants (< 2000 grams), but the difference disappeared within the first months of life. Almost all measurements after 6 months of age were of lower birth weight infants (< 2000 grams) and their systolic blood pressure level of 101.1 +/- 6.4 mm Hg (mean +/- S.D.; n = 38) appeared to remain unchanged in later infancy. Using analysis of variance, four perinatal factors were found to be associated by analysis of variance with elevated blood pressure values recorded in the clinic. These were instrumental vaginal delivery, prolonged ventilatory support, presence of patent ductus arteriosus and high blood pressure during the neonatal period. However, when multiple regression analysis was applied, only neonatal hypertension was significantly associated with subsequent elevated values measured in the clinic.