Expanding the screening for diabetes in pregnancy: overmedicalization or the right thing to do?

Over the years, what started as a screening to determine which pregnant women were at risk of developing diabetes later in life has changed progressively into a screening for diabetes during pregnancy. From only screening women with risk factors, the medical community has moved to a universal screening for glucose intolerance during pregnancy. Recently, the push has been to expand this screening earlier in pregnancy and to identify ever milder forms of glucose intolerance. To address these controversial issues, the National Institutes of Health convened a consensus panel to review the evidence and make clinical and research recommendations. The panel statement is published in this issue of Obstetrics & Gynecology (see page 358). The panel recognized the controversies around screening and the problem of inconsistent guidelines, from timing of screening to type of test to cutoffs for glucose levels. The panel also emphasized the dearth of evidence on which to base expanding the screening and definition of gestational diabetes mellitus (GDM). The panel identified the need to compare any of the newly proposed methods with the most prevalent method of screening in the United States (the two-step approach), particularly relating to maternal and neonatal benefit. The major concern with expanding screening without adequate evidence of benefit is the unintended consequences. The panel highlighted the potential for harm from identifying more women with glucose intolerance during pregnancy, some of whom have even milder forms of intolerance than those identified using the current methods. A cascade of events is inevitable once a woman is labeled as having GDM. These include more frequent prenatal visits, more fetal and maternal surveillance, and more interventions, including induction of labor, late preterm birth, early term birth, and cesarean delivery. The increased resources that would be needed to provide additional care for the up to 18% of pregnant women who would be labeled as having GDM under the proposed onestep screening method could unintentionally divert resources from other components of prenatal care, potentially causing harm in other ways. All of these unintended consequences need to be evaluated before recommending changes to our current screening method because they have the potential to negate any purported benefit from earlier or more sensitive identification of glucose intolerance. When considering the overall effect of expanding the screening and definition of GDM, we need to keep in mind the additional burden in the postpartum and postnatal periods for the identified women and their children. Although there is good evidence of an association over a continuum between glucose intolerance and adverse maternal and perinatal outcomes, the issue to address is whether intervention benefits all those See related article on page 358.