Fatores perinatais e níveis pressóricos de escolares em duas cidades brasileiras

Abstract

Introduction: Changes in the gestational period and at the time of delivery can exert influence on blood pressure in adulthood, however it is still unknown if there is this effect in childhood and adolescence. Objective: The aim of this work was to assess the association of perinatal factors in the blood pressure levels of schoolchildren. Methods: Data from two birth cohorts in two Brazilian cities were evaluated. In the perinatal baseline, 2,858 mothers-babies binomials participated in Ribeirão Preto (RP) in 1994 and in São Luiz (SL) there was a participation of 2,443 mothers-babies in 1997/98. The follow-up in children during their school lives was done in the year of 2005; when 869 children (by the age of 10/11 years) were followed in RP and 805 (by the age of 7/9 years) in SL. The variables had gathered in the perinatal questionnaire were the following: sex, birthplace, mode of delivery, gestational age and birth weight. At the follow-up, further variables had collected: family income, maternal schooling, anthropometric measurements of the child and two measures of the child's blood pressure. An exploratory model using the perinatal period variables was analyzed in association with the outcome, systolic blood pressure (SBP). Multiple linear regression analysis of perinatal factors on the SBP levels was performed, adjusted to sociodemographic variables and anthropometric measurements of children. In the second article, the data from Ribeirão Preto cohort only were analyzed and the response variables, mean systolic blood pressure (SBP) and mean diastolic blood pressure (DBP), were standardized in a specific blood pressure z-score by age, sex and height. Multivariate analysis were performed by linear regression analysis to verify the association between the z-score of systolic and diastolic blood pressures and perinatal factors. Thus for analysis of the association between cesarean delivery and the z-scores of SBP e DBP, it was identified the minimum set of variables indicated by a Directed Acyclic Graph (DAG) for adjustment, which were maternal schooling at birth, maternal age, family income at birth and maternal smoking. For this adjusted analysis, two models were used: a multiple linear regression model (MLR) and a causal estimation model by the inverse of the probability weight (CEM). Results: In the first article, it was observed in RP an increase in mean SBP of 2.69 mmHg (95% CI = 0.86; 4.53) in those born by cesarean delivery and in SL, among preterm infants, an increase of 2.51 mmHg (95% CI = 0.81, 4.23). In the second article, in the analyzes adjusted in the two proposed models, there was statistical significance in the two methods between cesarean delivery and the SBP of students with a coefficient of 0.22 (p-value=0.01) in the MLR based on the DAG and coefficient of 0.25 (p-value=0.004) in CEM and the same was not observed with PAD. Conclusion: In the first article, it was drawn an association between cesarean delivery and blood pressure of schoolchildren from the city with the highest socioeconomic status, but not in those one from the poorest city. In the second article, this finding was reinforced and established a possible causality relationship between cesarean delivery and the future levels of SBP.