First Trimester Biological Markers for the Prediction of Pregnancy-Induced Hypertension

Abstract

The purpose of this study is to predict pregnancy-induced hypertension (PIH) by standard methods at the first antenatal visit prior to the 12th gestational week (GW). This is a retrospective study of 1189 primipara and 957 multipara who delivered singleton babies having no major malformations after the 32nd GW. Multiple regression analysis for the development of PIH was performed using the mean arterial blood pressure (MBP), body mass index (BMI), hematocrit count at the first visit prior to the 12th GW, a family history of hypertension number of pregnancies, number of deliveries, past history of hypertension and evidence of threatened abortion as explanatory variables in primipara and multipara, respectively. We obtained a significant regression equation in both primipara and multipara. Multiple correlation coefficient for primipara was 0.40223 (p < 0.01) and for multipara was 0.50764 (p < 0.01). When MBP was over 80 mm Hg, BMI was over 23.6, a family history of hypertension was present, or a past history of hypertension was present, these variables were significantly correlated with the development of PIH both in primipara and multipara. By combining these variables, we obtained 32.7% positive predictive value, 93.5% negative predictive value, 31.7% sensitivity, and 93.7% specificity in primipara and 24.6%, 96.7%, 52.6%, and 89.8% in multipara, respectively. As the incidence of PIH was 8.7% in primipara and 5.9% in multipara, we could predict 3.7 and 4.1 times higher than the true incidence. PIH can therefore be predicted by the simple combination of MBP, BMI, a family history of hypertension, and a past history of hypertension prior to the 12th GW. It can also be predicted by the multiple-regression equation with the use of nine explanatory variables.