The human gut microbiome can modulate metabolic health and affect insulin resistance, and it may play an important role in the etiology of gestational diabetes mellitus (GDM). Here, we compared the gut microbial composition of 43 GDM patients and 81 healthy pregnant women via whole-metagenome shotgun sequencing of their fecal samples, collected at 21–29 weeks, to explore associations between GDM and the composition of microbial taxonomic units and functional genes. A metagenome-wide association study identified 154 837 genes, which clustered into 129 metagenome linkage groups (MLGs) for species description, with significant relative abundance differences between the 2 cohorts. Parabacteroides distasonis, Klebsiella variicola, etc., were enriched in GDM patients, whereas Methanobrevibacter smithii, Alistipes spp., Bifidobacterium spp., and Eubacterium spp. were enriched in controls. The ratios of the gross abundances of GDM-enriched MLGs to control-enriched MLGs were positively correlated with blood glucose levels. A random forest model shows that fecal MLGs have excellent discriminatory power to predict GDM status. Our study discovered novel relationships between the gut microbiome and GDM status and suggests that changes in microbial composition may potentially be used to identify individuals at risk for GDM.

Few studies have explored the relationship between dietary patterns and the risk of gestational diabetes mellitus (GDM). Evidence from non-Western areas is particularly lacking. In the present study, we aimed to examine the associations between dietary patterns and the risk of GDM in a Chinese population. A total of 3063 pregnant Chinese women from an ongoing prospective cohort study were included. Data on dietary intake were collected using a FFQ at 24-27 weeks of gestation. GDM was diagnosed using a 75 g, 2 h oral glucose tolerance test. Dietary patterns were determined by principal components factor analysis. A log-binomial regression model was used to examine the associations between dietary pattern and the risk of GDM. The analysis identified four dietary patterns: vegetable pattern; protein-rich pattern; prudent pattern; sweets and seafood pattern. Multivariate analysis showed that the highest tertile of the vegetable pattern was associated with a decreased risk of GDM (relative risk (RR) 0·79, 95 % CI 0·64, 0·97), compared with the lowest tertile, whereas the highest tertile of the sweets and seafood pattern was associated with an increased risk of GDM (RR 1·23, 95 % CI 1·02, 1·49). No significant association was found for either the protein-rich or the prudent pattern. The protective effect of a high vegetable pattern score was more evident among women who had a family history of diabetes (P for interaction¼ 0·022). These findings suggest that the vegetable pattern was associated with a decreased risk of GDM, while the sweets and seafood pattern was associated with an increased risk of GDM. These findings may be useful in dietary counselling during pregnancy.

BackgroundVitamin D deficiency has been linked to an increased risk of asthma. This study aimed to quantify the effect of early life vitamin D status on asthma and wheeze later in life.MethodsPubMed, Embase, CINAHL, and CNKI databases, the Cochrane Central Register of Controlled Trials, and Google Scholar were searched up to July 2017. We included randomized controlled trials (RCTs) and cohort studies with vitamin D level in blood (maternal or cord or infant) or intake (maternal intake during pregnancy or infant intake) and asthma and/or wheeze. Two reviewers independently extracted data. Fixed- and random-effects models were used to summarize the risk estimates of comparisons between highest vs. lowest vitamin D categories.ResultsOf the 1485 studies identified, three RCTs and 33 cohort studies were included. We did not include the RCTs (1619 participants) in the meta-analysis as the comparators and outcome definitions were heterogenous. Three RCTs reported a non-statistically significant effect of vitamin D supplementation during pregnancy on offspring wheeze/asthma at 3 years of age. Pooled estimates of cohort studies suggest no association between antenatal blood vitamin D levels or vitamin D intake and offspring asthma assessed either > 5 years or ≤ 5 years. The estimate for blood vitamin D remained unchanged when two studies assessing asthma in adulthood were excluded, but a significant inverse association emerged between vitamin D intake and childhood asthma. We found no association between antenatal vitamin D level and wheeze. On the other hand, vitamin D intake during pregnancy may have a protective effect against wheeze.ConclusionsThe pooled estimates from cohort studies show no association between antenatal blood vitamin D level and asthma/wheeze in later life. Whereas, the pooled estimates from cohort studies suggest that antenatal vitamin D intake may have an effect on childhood asthma > 5 years or childhood wheeze. The inconsistent results from studies assessing vitamin D either in blood or intake may be explained by previously reported non-linear association between blood vitamin D3 and childhood asthma. Further trials with enough power and longer follow-up time should be conducted to confirm the results.Electronic supplementary materialThe online version of this article (10.1186/s12890-018-0679-4) contains supplementary material, which is available to authorized users.

BackgroundThere remains uncertainty regarding whether a single fasting glucose measurement is sufficient to predict risk of adverse perinatal outcomes.MethodsWe included 12,594 pregnant women who underwent a 75-g oral glucose-tolerance test (OGTT) at 22–28 weeks' gestation in the Born in Guangzhou Cohort Study, China. Outcomes were large for gestational age (LGA) baby, cesarean section, and spontaneous preterm birth. We calculated the area under the receiver operator characteristic curves (AUCs) to assess the capacity of OGTT glucose values to predict adverse outcomes, and compared the AUCs of different components of OGTT.Results1325 women had a LGA baby (10.5%). Glucose measurements were linearly associated with LGA, with strongest associations for fasting glucose (odds ratio 1.37, 95% confidence interval 1.30–1.45). Weaker associations were observed for cesarean section and spontaneous preterm birth. Fasting glucose have a comparable discriminative power for prediction of LGA to the combination of fasting, 1 h, and 2 h glucose values during OGTT (AUCs, 0.611 vs. 0.614, P = 0.166). The LGA risk was consistently increased in women with abnormal fasting glucose (≥ 5.1 mmol/l), irrespective of 1 h or 2 h glucose levels.ConclusionsA single fasting glucose measurement performs comparably to 75-g OGTT in predicting risk of having a LGA baby.

This study aimed to examine the reproducibility and validity of a new food frequency questionnaire (FFQ) used in a birth cohort study to estimate the usual consumption frequencies of foods during pregnancy. The reference measure was the average of three inconsecutive 24 h diet recalls (24 HR) administrated between two FFQs, and the reproducibility was measured by repeating the first FFQ (FFQ1) approximately eight weeks later (FFQ2). A total of 210 pregnant women from the Born in Guangzhou Cohort Study (BIGCS) with full data were included in the analysis. The Spearman’s correlation coefficients of FFQ1 and FFQ2 ranged from 0.33 to 0.71. The intraclass correlation coefficients of the two FFQs ranged from 0.22 to 0.71. The Spearman’s correlation coefficients of the 24 HR and FFQ2 ranged from 0.23 to 0.62. Cross-classification analysis showed 65.1% of participants were classified into same and contiguous quintiles, while only 3.2% were misclassified into the distant quintiles. Bland-Altman methods showed good agreement for most food groups across the range of frequencies between FFQ1 and FFQ2. Our findings indicated that the reproducibility and validity of the FFQ used in BIGCS for assessing the usual consumption frequencies of foods during pregnancy were acceptable.