Comparación de biomarcadores de primer trimestre en gestantes normotensas según su grado de obesidad en el tercer trimestre

Abstract

IntroductionThis study aims to improve the efficiency of aneuploidy screening in the first trimester of pregnancy by creating predictive models that serve to identify pregnant women at risk of becoming overweight or obese in the third trimester and to using them to implement preventive measures of obesity. MethodsAn ambispective, observational, primary care study was conducted in which a total of 380 records corresponding to as many pregnancies were collected. Samples were collected from patients of 6 health centres, in order to determine the following variables: age at gestation, pregnancy-associated plasma protein A (PAPP-A) (mU/ml), human chorionic gonadotropin (b-HCG) (ng/ml), sample collection week for first trimester screening, body mass index at 12 and 28 weeks gestation (BMI), TSH at 12 weeks gestation, and systolic, diastolic, and mean arterial blood pressure (SBP, DBP, and MBP, respectively) at 12 and 28 weeks gestation. The BMI variable was recoded at 28 weeks, classifying pregnant women as normal weight (BMI<25), overweight (BMI 25-29.99), or obese (BMI≥30). The recoded BMI at 28 weeks was the variable resulting from the ordinal logistic regression model. An ANOVA study of several factors was used to discern differences between arterial pressures. A 5% alpha error was accepted. ResultsThe PAPP-A and b-HCG medians measured in the first trimester are progressively lower in the groups of pregnant women with normal weight, overweight, and obesity observed in the third trimester. These values are predictors of the weight in the third trimester (ordinal logistic regression) (PAPP-A: P=.022; b-HCG: P=.002). No pregnant woman developed pre-eclampsia. The SBP, DBP, and MBP in the third trimester were significantly different (ANOVA in several factors; P<.05). DiscussionThe ordinal logistic regression demonstrates that the decrease in the observed values of PAPP-A and b-HCG in the first trimester is a predictor of the level of significant and gradual obesity in a sample of normotensive pregnant women. An ordinal regression model including the 12-week BMI was not made due to the internal collinearity that it would provide if the result variable was based on it. The predictive effect of b-HCG is more homogeneous than that of PAPP-A for the level of overweight and obesity.