Despite the increasing epidemic of diabetes mellitus affecting populations at different life stages, the global burden of gestational diabetes mellitus (GDM) is not well assessed. Systematically synthesized data on global prevalence estimates of GDM are lacking, particularly among developing countries. The hyperglycemic intrauterine environment as exemplified in pregnancies complicated by GDM might not only reflect but also fuel the epidemic of type 2 diabetes mellitus (T2DM). We comprehensively reviewed available data in the past decade in an attempt to estimate the contemporary global prevalence of GDM by country and region. We reviewed the risk of progression from GDM to T2DM as well. Synthesized data demonstrate wide variations in both prevalence estimates of GDM and the risk of progression from GDM to T2DM. Direct comparisons of GDM burden across countries or regions are challenging given the great heterogeneity in screening approaches, diagnostic criteria, and underlying population characteristics. In this regard, collaborative efforts to estimate global GDM prevalence would be a large but important leap forward. Such efforts may have substantial public health implications in terms of informing health policy makers and healthcare providers for disease burden and for developing more targeted and effective diabetes prevention and management strategies globally.

Aims/hypothesis The aim of this study was to prospectively and longitudinally investigate maternal iron status during early to mid-pregnancy, and subsequent risk of gestational diabetes mellitus (GDM), using a comprehensive panel of conventional and novel iron biomarkers. Methods A case-control study of 107 women with GDM and 214 controls (matched on age, race/ethnicity and gestational week during blood collection) was conducted within the the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies-Singleton Cohort (2009)(2010)(2011)(2012)(2013), a prospective and multiracial pregnancy cohort. Plasma hepcidin, ferritin and soluble transferrin receptor (sTfR) were measured and sTfR:ferritin ratio was derived, twice before GDM diagnosis (gestational weeks 10-14 and 15-26) and at weeks 23-31 and 33-39. GDM diagnosis was ascertained from medical records. Adjusted ORs (aORs) for GDM were estimated using conditional logistic regression analysis, adjusting for demographics, prepregnancy BMI and other major risk factors. Results Hepcidin concentrations during weeks 15-26 were 16% higher among women with GDM vs controls (median 6.4 vs 5.5 ng/ml; p = 0.02 ), and were positively associated with GDM risk; the aOR (95% CI) for highest vs lowest quartile was 2.61 (1.07, 6.36). Ferritin levels were also positively associated with GDM risk; the aOR (95% CI) for highest vs lowest quartile was 2.43 (1.12, 5.28) at weeks 10-14 and 3.95 (1.38, 11.30) at weeks 15-26. The sTfR:ferritin ratio was inversely related to GDM risk; the aOR (95% CI) for highest vs lowest quartile was 0.33 (0.14, 0.80) at weeks 10-14 and 0.15 (0.05, 0.48) at weeks 15-26. Conclusions/interpretation Our findings suggest that elevated iron stores may be involved in the development of GDM from as early as the first trimester. This raises potential concerns for the recommendation of routine iron supplementation among iron-replete pregnant women.

Aims/hypothesis Depression and glucose intolerance commonly co-occur among non-pregnant individuals; however, the temporal relationship between gestational diabetes (GDM) and depression during pregnancy and the postpartum period is less understood. Our objective was to assess longitudinal associations between depression early in pregnancy and GDM risk, as well as GDM and subsequent risk of postpartum depression. Methods Data came from the prospective National Institute of Child Health and Human Development Fetal Growth Studies-Singleton cohort (2009–2013), and had been collected at 12 US clinical centres. Pregnant women without psychiatric disorders, diabetes or other chronic conditions before pregnancy were followed throughout pregnancy (n=2477). Only women with GDM and matched controls were followed up at 6 weeks postpartum (n=162). GDM was ascertained by a review of the medical records. Depression was assessed in the first (8–13 gestational weeks) and second (16–22 weeks) trimesters and at 6 weeks postpartum using the Edinburgh Postnatal Depression Scale. Postpartum depression was defined as a depressive symptom score ≥10 or antidepressant medicine use after delivery. RR and 95% CI we adjusted for pre-pregnancy BMI and other risk factors. GDM was considered to be the outcome for the first set of analyses, with depression in the first and second trimesters as the exposures. Postpartum depression was considered as the outcome for the second set of analyses, with GDM as the exposure. Results Overall, comparing the highest and lowest quartiles of first-trimester depression scores, the scores from the highest quartile were associated with a significant twofold (95% CI 1.06, 3.78) increased risk of GDM, but this was attenuated to 1.72-fold (95% CI 0.92, 3.23) after adjustment; the second-trimester results were similar. The risk was stronger and significant in both trimesters among non-obese women (p for trend 0.02 and 0.01, respectively), but null for obese women. Women with persistently high depression scores in both trimesters had the greatest risk of GDM (highest vs lowest quartile in both trimesters: adjusted RR 3.21, 95% CI 1.00–10.28). GDM was associated with an adjusted 4.62-fold (95% CI 1.26, 16.98) increased risk of subsequent postpartum depression. Conclusions/interpretation This prospective study demonstrates a modest association between depressive symptoms early in pregnancy and an increased risk of incident GDM, as well as between GDM and subsequent postpartum depression risk, highlighting pregnancy and the postpartum period as an important susceptible time window during the life course for the interplay between depression and glucose intolerance phenotypes. GDM risk associated with elevated depressive symptoms was particularly high among non-obese women and women with symptoms persisting across the first two trimesters of pregnancy.

Background Exposures to extreme ambient temperature and air pollution are linked to adverse birth outcomes, but the associations with small for gestational age (SGA) and term low birthweight (tLBW) are unclear. We aimed to investigate exposures to site-specific temperature extremes and selected criteria air pollutants in relation to SGA and tLBW. Methods We linked medical records of 220,572 singleton births (2002–2008) from 12 US sites to local temperature estimated by the Weather Research and Forecasting model, and air pollution estimated by modified Community Multiscale Air Quality models. Exposures to hot (>95th percentile) and cold (<5th percentile) were defined using site-specific distributions of daily temperature over three-month preconception, each trimester, and whole-pregnancy. Average concentrations of five criteria air pollutants and six fine particulate matter constituents were also calculated for these pregnancy windows. Poisson regression with generalized estimating equations calculated the relative risks (RR) and 95% confidence intervals for SGA (weight <10th percentile conditional on gestational age and sex) and tLBW (≥37 weeks and <2,500 grams) associated with an interquartile range increment of air pollutants, and cold or hot compared to mild (5–95th percentile) temperature. Models were adjusted for maternal demographics, lifestyle, and clinical factors, season, and site. Results Compared to mild temperature, cold exposure during trimester 2 [RR: 1.21 (1.05–1.38)], trimester 3 [RR: 1.18 (1.03–1.36)], and whole-pregnancy [RR: 2.57 (2.27–2.91)]; and hot exposure during trimester 3 [RR: 1.31 (1.15–1.50)] and whole-pregnancy [RR: 2.49 (2.20–2.83)] increased tLBW risk. No consistent association was observed between temperature and SGA. Air pollutant analyses were generally null but preconception elemental carbon was associated with a 4% increase in SGA while dust particles increased tLBW by 10%. Particulate matter ≤10 microns in the second trimester and whole pregnancy also appeared related to tLBW. Conclusions: Our findings suggest prenatal exposures to extreme ambient temperature relative to usual environment may increase tLBW risk. Given concerns related to climate change, these findings merit further investigation.

To examine racial/ethnic disparities in the prevalence of diabetes and prediabetes by BMI category. RESEARCH DESIGN AND METHODS In a consortium of three U.S. integrated health care systems, 4,906,238 individuals aged ‡20 years during 2012-2013 were included. Diabetes and prediabetes were ascertained by diagnosis and laboratory results; antihyperglycemic medications were also included for diabetes ascertainment. RESULTS The age-standardized diabetes and prediabetes prevalence estimates were 15.9% and 33.4%, respectively. Diabetes but not prediabetes prevalence increased across BMI categories among all racial/ethnic groups (P for trend < 0.001). Racial/ethnic minorities reached a given diabetes prevalence at lower BMIs than whites; Hawaiians/Pacific Islanders and Asians had a diabetes prevalence of 24.6% (95% CI 24.1-25.2%) in overweight and 26.5% (26.3-26.8%) in obese class 1, whereas whites had a prevalence of 23.7% (23.5-23.8%) in obese class 2. The agestandardized prediabetes prevalence estimates in overweight among Hispanics (35.6% [35.4-35.7%]), Asians (38.1% [38.0-38.3%]), and Hawaiians/Pacific Islanders (37.5% [36.9-38.2%]) were similar to those in obese class 4 among whites (35.3% [34.5-36.0%]), blacks (36.8% [35.5-38.2%]), and American Indians/Alaskan Natives (34.2% [29.6-38.8%]). In adjusted models, the strength of association between BMI and diabetes was highest among whites (relative risk comparing obese class 4 with normal weight 7.64 [95% CI 7.50-7.79]) and lowest among blacks (3.16 [3.05-3.27]). The association between BMI and prediabetes was less pronounced. CONCLUSIONS Racial/ethnic minorities had a higher burden of diabetes and prediabetes at lower BMIs than whites, suggesting the role of factors other than obesity in racial/ethnic disparities in diabetes and prediabetes risk and highlighting the need for tailored screening and prevention strategies.

. We also thank the Emmes Corporation, Rockville, MD, which provided data coordination; and the Texas A&M Supercomputing Facility and the Texas Advanced Computing Center, which provided computing resources essential to completing exposure estimations in this study. The authors also wish to thank E. Schisterman for his expert advice on the case-crossover design.

Our findings illustrated positive associations between intrauterine exposure to ASBs and birth size and risk of overweight/obesity at 7 years. Data with longer follow-up are warranted.

Objectives To investigate whether prepregnancy obesity is associated with adverse pregnancy outcomes among women without chronic disease. Methods Singleton deliveries (n=112,309) among mothers without chronic diseases in the Consortium on Safe Labor, a retrospective U.S. cohort, were analyzed using Poisson regression with robust variance estimation. Relative risks (RR) and 95% confidence intervals (CI) estimated perinatal risks in relation to pre-pregnancy obesity status adjusted for age, race–ethnicity, parity, insurance, smoking and alcohol use during pregnancy, and study site. Results Obstetric risks were variably (and mostly marginally) increased as BMI category and obesity class increased. In particular, the risk of gestational hypertensive disorders, gestational diabetes, cesarean delivery and induction increased in a dose-response fashion. For example, the percent of gestational diabetes among obese class III women was 14.6% in contrast to 2.8% among normal BMI women, corresponding RR (95% CI) 1.99(1.86–2.13), 2.94(2.73–3.18), 3.97(3.61–4.36) and 5.47(4.96–6.04) for overweight, obese class I, obese class II, and obese class II women, respectively, compared with normal BMI women. Similarly, neonatal risks increased in a dose-response fashion with maternal BMI status including preterm birth <32 weeks, large for gestational age (LGA), transient tachypnea, sepsis and intensive care unit admission. The percent of LGA infants increased from 7.9% among normal BMI women to 17.3% among obese class III women and RR increased to 1.52(1.45–1.58), 1.74(1.65–1.83), 1.93(1.79–2.07) and 2.32(2.14–2.52) as BMI category increased. Conclusions Prepregnancy obesity is associated with increased risks of a wide range of adverse pregnancy and neonatal outcomes among women without chronic diseases.