NEW ORLEANS (FRONTLINE MEDICAL NEWS) – A single, random, first-trimester maternal plasma glucose measurement is superior to an oral glucose tolerance test later in pregnancy as a predictor of congenital heart disease in newborns, Emmi Helle, MD, reported at the American Heart Association scientific sessions.

This finding from a large retrospective study, if confirmed in a prospective data set, is likely to be practice changing. At present, a 1-hour oral glucose tolerance test in the second or third trimester is considered the best means of identifying pregnant women who ought to undergo fetal echocardiography for prenatal diagnosis of congenital heart disease, noted Dr. Helle of Stanford (Calif.) University.

She reported on 19,197 pregnancies at Stanford Medical Center and the Geisinger Health System, 811 (4.22%) of which resulted in babies with congenital heart disease. In a multivariate logistic regression analysis adjusted for prepregnancy body mass index, diagnosis of diabetes prior to pregnancy, and maternal age at delivery, for every 10-mg/dL increase in plasma glucose the risk of delivering a baby with congenital heart disease rose by 8%. In contrast, an abnormal oral glucose tolerance test at week 24-28 wasn’t a significant predictor of congenital heart disease in the offspring.

An elevated random plasma glucose value in the first trimester was broadly predictive of increased risk for a variety of congenital heart anomalies, not just, for example, cyanotic conditions.

Fetal heart development is completed during the first trimester, Dr. Helle observed.

Her study received a warm reception. Michael A. Portman, MD , singled it out in his final-day wrap-up of the meeting’s highlights in the field of congenital heart disease.

Several studies have demonstrated that prenatal diagnosis of congenital heart disease results in improved surgical outcomes in newborns. The question is, how to get the right women – those at increased risk – to diagnostic fetal echocardiography. Guidelines suggest but don’t mandate on the basis of weak evidence that an oral glucose tolerance test performed in the second or early third trimester may be a useful means of screening mothers for fetal imaging. Dr. Helle’s study points to a better way.

“Hopefully we can change our guidelines and make them more scientific for identification of mothers who should undergo fetal echocardiography,” said Dr. Portman, professor of pediatrics at the University of Washington, Seattle, and director of pediatric cardiovascular research at Seattle Children’s Hospital.

Dr. Helle and Dr. Portman reported having no relevant financial interests.