Increasing prevalence of gestational diabetes mellitus: a public health perspective.

R ecent data show that gestational diabetes mellitus (GDM) prevalence has increased by 10 –100% in several race/ethnicity groups during the past 20 years. A true increase in the prevalence of GDM, aside from its adverse consequences for infants in the newborn period, might also reflect or contribute to the current patterns of increasing diabetes and obesity, especially in the offspring. Therefore, the public health aspects of increasing GDM need more attention. The frequency of GDM usually reflects the frequency of type 2 diabetes in the underlying population (1,2). Established risk factors for GDM are advanced maternal age, obesity, and family history of diabetes (3). Unquestionably, there are ethnic differences in the prevalence of GDM (4–15). In the U.S., Native Americans, Asians, Hispanics, and AfricanAmerican women are at higher risk for GDM than non-Hispanic white women (4–6,8–11,13–15). In Australia, GDM prevalence was found to be higher in women whose country of birth was China or India than in women whose country of birth was in Europe or Northern Africa (7). GDM prevalence was also higher in Abor ig ina l women than in nonAboriginal women (12). In Europe, GDM has been found to be more common among Asian women than among European women (16). The proportion of pregnancies complicated by GDM in Asian countries has been reported to be lower than the proportion observed in Asian women living in other continents (17). In India, GDM has been found to be more common in women living in urban areas than in women living in rural areas (18). The trend toward older maternal age (19), the epidemic of obesity (20) and diabetes (21), and the decrease in physical activity (22) and the adoption of modern lifestyles in developing countries (23) may all contribute to an increase in the prevalence of GDM. Because GDM is associated with several perinatal complications (3), and because women with GDM and their offspring are also at increased risk of developing diabetes later in life (3), it is critical to assess trends in GDM prevalence to allocate appropriate resources to perinatal management and postpartum diabetes prevention strategies. Characterizing trends in GDM might also help to understand possible mechanisms for the increase of obesity and type 2 diabetes, especially in children. Recent data (7,11– 15) show that GDM prevalence has increased by 16–127% in several race/ ethnicity groups during the past 20 years. These variations may depend on differences in methodology and study populations across studies. Methodological issues are described below as well as studies of trends in GDM. Some studies (7,11) calculated the “cumulative incidence” (defined as the percentage of pregnancies in which GDM was recognized) because GDM frequency was calculated among screened pregnancies regardless of whether they delivered an infant. However, most of the studies (12–14,15) identified only women who delivered, and therefore they calculated the “prevalence” of GDM at delivery. For simplicity, the term “prevalence” of GDM will be used for all studies, since the GDM cumulative incidence estimates are similar to the prevalence estimates, given the small number of preggnancies that were screened but did not deliver an infant.