Antenatal fetal testing in pregnancies complicated by Gestational Diabetes Mellitus: Why, who and how?

Most obstetricians adopt some form of strategy for antenatal fetal testing in pregnancies complicated by gestational diabetes mellitus (GDM). There are, however, wide differences of opinion among providers as to the preferred protocol for such testing. The optimal method of fetal surveillance, the gestational age at which to start testing, the frequency of testing and even whether all patients with GDM require antenatal testing are all controversial, unresolved issues. Indeed, in the absence of prospective, randomized clinical trials, it is impossible to determine whether antenatal fetal testing is beneficial in uncomplicated GDM. Moreover, it appears that, even with the employment of well-defined antenatal testing protocols, it is unavoidable that some women with GDM will experience an unexplained third-trimester stillbirth. Not least important are the issues of cost-benefit with a strategy of universal antenatal testing in GDM and the rate of unnecessary obstetric interventions that may result from such a strategy. Consequently, the Diabetes in Pregnancy Study Group of North America has proposed a randomized clinical trial as a first effort to try and resolve some of these perplexing issues.