Increased blood pressure in adolescents who were small for gestational age at birth: A cohort study in Brazil

Abstract

Background. This paper studies the relationship between birthweight for gestational age and blood pressure in adolescents aged 14-15 years in southern Brazil. Methods. A sample of 1076 adolescents belonging to a cohort of over 6000 children born in 1982 in Pelotas, southern Brazil, was studied in 1997. All households in a sample of 25% of the city's census tracts were visited and all adolescents born in 1982 were interviewed, weighed, and their blood pressures were measured twice. Data from the adolescents were linked to the database through their names and dates of births. Results. High diastolic and systolic pressure (defined as > 95th percentile) were significantly more frequent among adolescents who were born below the 10th percentile of birthweight for gestational age. No association was found between high blood pressure and low birthweight or preterm births. In a multiple linear regression analysis, the association between birthweight for gestational age and blood pressure was not statistically significant after adjusting for age, sex, skin colour and family income. However, when the current body mass index and height were added to the model both diastolic and systolic pressure were significantly associated with birthweight for gestational age, and adolescents who were small for gestational age at birth presented a mean elevation of 3.08 mmHg for diastolic pressure and 2.89 mmHg for systolic pressure. Conclusions. There is an inverse association between birthweight for gestational age and blood pressure during adolescence. This association, however, is only disclosed when the negative confounding effect of the body mass index is controlled for. The same association is not found when the effects of birthweight and gestational age on blood pressure are analysed separately. It appears therefore that the elevation of blood pressure during adolescence only occurs when there was intra-uterine growth retardation.