Risk factors associated with preeclampsia in healthy nulliparous women,☆☆,,★★

Presented at the Seventeenth Annual Meeting of the Society of Perinatal Obstetricians, Anaheim, California, January 20-25, 1997.
https://doi.org/10.1016/S0002-9378(97)70004-8Get rights and content

Abstract

Objective: Our goal was to identify risk factors for the development of preeclampsia in nulliparous women enrolled in a multicenter trial comparing calcium supplementation to a placebo. Study Design: A total of 4589 women from five centers was studied. Analysis of risk factors for preeclampsia was performed in 4314 who carried the pregnancy to >20 weeks. Baseline systolic and diastolic blood pressure, demographic characteristics, and findings after randomization were examined for the prediction of preeclampsia. Preeclampsia was defined as hypertension (diastolic blood pressure ≥90 mm Hg on two occasions 4 hours to 1 week apart) and proteinuria (≥300 mg/24 hours, a protein/creatinine ratio ≥0.35, one dipstick measurement ≥2+ or two dipstick measurements ≥1+ at an interval as specified for diastolic blood pressure). Results: Preeclampsia developed in 326 women (7.6%). The first analysis treated each risk factor as a categoric variable in a univariate regression. Maternal age, blood group and Rh factor, alcohol use, previous abortion or miscarriage, private insurance, and calcium supplementation were not statistically significant. Risk factors initially found to be significant were body mass index, systolic blood pressure, diastolic blood pressure, non-white race (African-American and other), clinical center, and smoking. Adjusted odds ratios computed with a Iogistic regression model revealed that body mass index (odds ratio 3.22 for ≥35 kg/m2 vs <19.8 kg/m2), systolic blood pressure (odds ratio 2.66 for ≥120 vs <101 mm Hg), diastolic blood pressure (odds ratio 1.72 for ≥61 mm Hg vs <60 mm Hg), and clinical center (odds ratio 1.85 for Memphis vs the other clinical centers) were statistically significant predictors of preeclampsia. Results of the final model fit revealed that preeclampsia risk increases significantly (p < 0.0001) with increased body mass index at randomization, as well as with increased systolic and diastolic blood pressure at randomization. Calcium supplementation had no effect on the risks posed by body mass index and blood pressure. Among risk factors developing after randomization, an abnormal result of a glucose screen (plasma glucose ≥140 mg/dl 1 hour after a 50 gm glucose challenge) was not found to be associated with a significant risk of preeclampsia. Conclusion: These risk factors should be of value in counseling women regarding preeclampsia and should aid in understanding the pathophysiologic characteristics of this syndrome.

Section snippets

Material and methods

The trial was designed and implemented by the members of the Calcium for Preeclampsia Prevention (CPEP) study group under the direction of the National Institute of Child Health and Human Development. Study procedures were conducted according to a common protocol and with identical data collection forms at all five participating clinical centers, located in Albuquerque, Birmingham, Cleveland, Memphis, and Portland.16 The trial included 4589 healthy nulliparous women who were followed up

Results

A total of 326 women who were delivered at ≥20 weeks' gestation (7.6%) had preeclampsia; 217 (5.0%) had mild preeclampsia and 109 (2.5%) had severe preeclampsia. Because the results of the trial revealed no differences in the incidence of preeclampsia between those assigned to calcium and those assigned to placebo,12 models were fit to data pooled over both treatment arms. The rate of preeclampsia ranged from 4.8% among women recruited in Portland to 12% among women recruited in Memphis. The

Comment

Several case-control studies and few longitudinal studies have evaluated the association between maternal clinical characteristics and the risk of subsequent preeclampsia.4, 5, 6, 7, 8, 9, 10, 11 Most of these studies lacked information about techniques of blood pressure measurements, as well as the methods used to assess the presence of proteinuria. Therefore there were differences regarding preeclampsia among these studies. Our study is unique in that it used standardized techniques to

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    From the Department of Obstetrics and Gynecology, University of Tennessee College of Medicine,a the Department of Obstetrics and Gynecology, University of Alabama,b the Department of Obstetrics and Gynecology, MetroHealth Medical Center,c The Emmes Corporation,d the Division of Epidemiology, Statistics, and Prevention Research, National Institute of Child Health and Human Development, National Institutes of Health,e and the Department of Obstetrics and Gynecology, University of New Mexico Health Sciences Center.f A complete list of members of the CPEP Study Group is shown at the end of the article.

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    Supported by the National Institute of Child Health and Human Development with cofunding from the National Heart, Lung, and Blood Institute under contract numbers N01-HD-1-3121 through 3126, N01-HD-2-3154, and N01-HD-5-3246.

    Reprints not available from the authors.

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