Background: Air pollution has been linked to gestational diabetes mellitus (GDM) but no studies have evaluated impact of preconception and early pregnancy air pollution exposures on GDM risk. Methods: Electronic medical records provided data on 219,952 singleton deliveries to mothers with (n=11,334) and without GDM (n=208,618). Average maternal exposures to particulate matter (PM) <2.5 microns (PM2.5) and PM2.5 constituents, PM <10 microns (PM10), nitrogen oxides (NOx), carbon monoxide, sulfur dioxide (SO2) and ozone (O3) were estimated for the 3-month preconception window, first trimester, and gestational weeks 1-24 based on modified Community Multiscale Air Quality models for delivery hospital referral regions. Binary regression models with robust standard errors estimated relative risks (RR) for GDM per interquartile range (IQR) increase in pollutant concentrations adjusted for study site, maternal age and race/ethnicity. Results: Preconception maternal exposure to NOX (RR=1.09, 95% CI: 1.04, 1.13) and SO2 (RR=1.05, 1.01, 1.09) were associated with increased risk of subsequent GDM and risk estimates remained elevated for first trimester exposure. Preconception O3 was associated with lower risk of subsequent GDM (RR=0.93, 0.90, 0.96) but risks increased later in pregnancy. Conclusion: Maternal exposures to NOX and SO2 preconception and during the first few weeks of pregnancy were associated with increased GDM risk. O3 appeared to increase GDM risk in association with mid-pregnancy exposure but not in earlier time windows. These common exposures merit further investigation.

High levels of racial inequality and socioeconomic inequality appear to increase the risk of SGA birth, particularly when they co-occur.

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.

Mesenchymal stem cells (MSCs)-derived exosomes exhibit protective effects on damaged or diseased tissues. Hypoxia-inducible factor 1α (HIF-1α) plays a critical role in bone development. However, HIF-1α is easily biodegradable under normoxic conditions. The bone-marrow-derived mesenchymal stem cells (BMSCs) were transfected with adenovirus carrying triple point-mutations (amino acids 402, 564, and 803) in the HIF-1α coding sequence (CDS). The mutant HIF-1α can efficiently express functional proteins under normoxic conditions. To date, no study has reported the role of exosomes secreted by mutant HIF-1α modified BMSCs in the recovery of the early steroid-induced avascular necrosis of femoral head (SANFH). In this study, we firstly analyzed exosomes derived from BMSCs modified by mutant (BMSC-Exos ) or wild-type HIF-1α (BMSC-Exos ). In vitro, we investigated the osteogenic differentiation capacity of BMSCs modified by BMSC-Exos or BMSC-Exos , and the angiogenesis effects of BMSC-Exos and BMSC-Exos on human umbilical vein endothelial cells (HUVECs). Besides, the healing of the femoral head was also assessed in vivo. We found that the potential of osteogenic differentiation of BMSCs treated with BMSC-Exos was higher than the wild-type group in vitro. In addition, BMSC-Exos stimulated the proliferation, migration, and tube formation of HUVECs in a dose-dependent manner. Compared with the BMSC-Exos or PBS control group, the injection of BMSC-Exos into the necrosis region markedly accelerated the bone regeneration and angiogenesis, which were indicated by the increased trabecular reconstruction and microvascular density. Taken together, our data suggest that BMSC-Exos facilitates the repair of SANFH by enhancing osteogenesis and angiogenesis.

Three recently completed longitudinal cohort studies have developed intrauterine fetal growth charts, one in the United States and two international. This expert review compares and contrasts the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies, INTERGROWTH-21st and World Health Organization Multicentre Growth Reference Study conclusions in light of differences in aims, sampling frames, and analytical approaches. An area of controversy is whether a single growth reference is representative of growth, regardless of ethnic or country origin. The INTERGROWTH and World Health Organization Fetal studies used a similar approach as the World Health Organization Multicentre Growth Reference Study for infants and children, the aim of which was to create a single international reference for the best physiological growth for children aged 0-5 years. INTERGROWTH made the same assumption (ie, that there would be no differences internationally among countries or racial/ethnic groups in fetal growth when conditions were optimal). INTERGROWTH found differences in crown-rump length and head circumference among countries but interpreted the differences as not meaningful and presented a pooled standard. The World Health Organization Multicentre Growth Reference Study was designed to create a pooled reference, although they evaluated for and presented country differences, along with discussion of the implications. The Eunice Kennedy Shriver National Institute of Child Health and Human Development Study was designed to assess whether racial/ethnic-specific fetal growth standards were needed, in recognition of the fact that fetal size is commonly estimated from dimensions (head circumference, abdominal circumference, and femur length) in which there are known differences in children and adults of differing racial/ethnic groups. A pooled standard would be derived if no racial/ethnic differences were found. Highly statistically significant racial/ethnic differences in fetal growth were found resulting in the publication of racial/ethnic-specific derived standards. Despite all 3 studies including low-risk status women, the percentiles for fetal dimensions and estimated fetal weight varied among the studies. Specifically, at 39 weeks, the 50th percentile for estimated fetal weight was 3502 g for whites, 3330 g for Hispanics, 3263 g for Asians, and 3256 for blacks in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Study, compared with 3186 g for INTERGROWTH and 3403 g for World Health Organization Multicentre Growth Reference Study. When applying these standards to a clinical population, it is important to be aware that different percentages of small- and large-for-gestational-age fetuses will be identified. Also, it may be necessary to use more restrictive cut points, such as the 2.5th or 97.5th, for small-for-gestational-age or large-for-gestational-age fetuses, respectively. Ideally, a comparison of diagnostic accuracy, or misclassification rates, of...

. 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.

ObjectivesTo examine nine-year trends and relationships regarding misperceptions of body size and dieting for weight loss among adolescents from 24 countries, and explore the influence of country-level overweight prevalence.MethodsSocio-demographic characteristics, body size perception, and dieting for weight loss were assessed in the Health Behaviour in School-aged Children survey conducted in 24 countries cross-sectionally at three time points (2001/02, 2005/06, 2009/10). Logistic regression models examined change over time in overestimation of body size in non-overweight adolescents, underestimation of body size in overweight adolescents, dieting for weight loss in non-overweight and overweight adolescents, and relationships between body size perception and dieting. Analyses were stratified by weight status and sex. Covariates included country-level overweight prevalence, family affluence, and country level of development. Body mass index was only included in models examining dieting for weight loss.ResultsCountry-level overweight prevalence increased over time (11.6% to 14.7%). Compared to Time 1, overweight adolescents had greater odds of body size underestimation at Time 3 (OR=1.68 for girls, OR=1.10 for boys), while non-overweight adolescents had lower odds of body size overestimation at Time 3 (OR=0.87 for girls, OR=0.89 for boys). Controlling for country-level overweight prevalence attenuated these relationships. Compared to Time 1, overweight and non-overweight boys were 10% more likely to diet at Time 3, while overweight and non-overweight girls were 19% and 16%, respectively, less likely to diet at Time 3. Controlling for country-level overweight prevalence did not impact trends in dieting for weight loss. Additionally, the association of self-perceived overweight with increased odds of dieting diminished over time.ConclusionsBody size perceptions among adolescents may have changed over time concurrent with shifts in country-level body weight. However, controlling for country-level overweight prevalence did not impact trends in dieting for weight loss, suggesting a potentially stronger impact of social comparison on weight-related perceptions than on behavior.

BackgroundDiets of U.S. adolescents and adults do not meet recommendations, increasing risk of chronic disease. This study examined trajectories and predictors of eating behaviors in U.S. youth from age 16–20 years, and evaluated longitudinal associations of eating behaviors with weight outcomes.MethodsData come from the first four waves (years) of the NEXT Generation Health Study, a nationally representative cohort of U.S. students in 10th grade during the 2009–2010 school year (n = 2785). Annual surveys queried frequency of food group intake (times/day of fruit and vegetables, whole grains, sugar-sweetened soda, sweet and salty snacks), and meal practices (days/week of breakfast, family meals, fast food, and television during meals). Body mass index (BMI, kg/m2) was calculated from self-reported height and weight. Adjusted generalized estimating equations and linear mixed models with multiple imputation for missing data estimated eating behavior trajectories overall and by baseline weight status (normal weight = 5 ≤ BMI%ile < 85, overweight = 85 ≤ BMI%ile < 95, obese = BMI%ile ≥ 95), accounting for the complex sampling design. Separate GEE models estimated longitudinal associations of food group frequencies with meal practices and of BMI with eating behaviors.ResultsEating behaviors tracked strongly from wave 1–4 (residual intraclass correlation = 41 % - 51 %). Across all baseline weight categories, frequency of food group intake and meal practices decreased over time, except for fast food, which remained stable. Fruit/vegetable intake frequency was associated positively with family meals (β ± SE = 0.33 ± 0.05) and breakfast (0.18 ± 0.03), and inversely with fast food (−0.31 ± 0.04), while whole grain intake frequency was associated positively with family meals (0.07 ± 0.02), television meals (0.02 ± 0.009) and breakfast (0.04 ± 0.01). Soda and snacks were positively associated with television meals (0.08 ± 0.008 and 0.07 ± 0.009, respectively) and fast food (0.24 ± 0.02 and 0.20 ± 0.03, respectively), while soda was inversely associated with breakfast frequency (−0.05 ± 0.01). Time-varying BMI was unrelated to eating behaviors other than an inverse association with time-varying snacks (−0.33 ± 0.12).ConclusionsStrong tracking over time supports the importance of early establishment of health-promoting eating behaviors in U.S. adolescents. Findings suggest meal practices may be important intervention targets. Lack of evidence for hypothesized associations of BMI and eating behaviors indicates the need for research confirming these findings using more precise measures of dietary intake.Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-015-0298-x) contains supplementary material, which is available to authorized users.