First-year blood pressure increase steepest in low birthweight newborns

The present research has been undertaken prospectively to study the impact of birthweight and growth pattern on blood pressure changes from birth through the first year of life.

Parents of newborns born at term (gestational age > 37 weeks) after uncomplicated pregnancies and in the absence of perinatal illness were randomly invited to allow their children to participate in the study. One hundred and forty-nine (84 male and 65 female) newborns were included in the present analysis. The newborns were divided into four groups according to birthweight: < 2500 g (n = 23); 2500-2999 g (n = 39); 3000-3500 g (n = 48); and > 3500 g (n = 39).

At birth systolic and diastolic blood pressure were significantly lower and heart rate was significantly higher in those children with the lowest birthweight as compared to those in the other groups. During the first month of life a significant trend, inversely related to birthweight, was present for systolic as well as diastolic blood pressure. After the first month of life, at 3, 6, 9 and at 12 months, systolic and diastolic blood pressure were similar across birthweight groups. In a multiple regression analysis, birthweight was a positive independent determinant of systolic blood pressure at birth and an inverse independent determinant of the increment of systolic blood pressure during the first month of life and of the systolic blood pressure at the end of the first year.

In summary, the present study goes further towards understanding blood pressure changes in low birthweight babies. Beginning at birth, both blood pressure values, as well as changes in blood pressure, provide information about the impact of intrauterine life on the risk of developing hypertension later in life.