The genetics of low and high birthweight and their relationship with cardiometabolic disease

AIMS/HYPOTHESIS

Low birthweight infants are at increased risk not only of mortality, but also of type 2 diabetes mellitus and CVD in later life. At the opposite end of the spectrum, high birthweight infants have increased risk of birth complications, such as shoulder dystocia, neonatal hypoglycaemia and obesity, and similarly increased risk of type 2 diabetes mellitus and CVD. However, previous genome-wide association studies (GWAS) of birthweight in the UK Biobank have primarily focused on individuals within the 'normal' range and have excluded individuals with high and low birthweight (<2.5 kg or >4.5 kg). The aim of this study was to investigate genetic variation associated within the tail ends of the birthweight distribution, to: (1) see whether the genetic factors operating in these regions were different from those that explained variation in birthweight within the normal range; (2) explore the genetic correlation between extremes of birthweight and cardiometabolic disease; and (3) investigate whether analysing the full distribution of birthweight values, including the extremes, improved the ability to detect genuine loci in GWAS.

METHODS

We performed case-control GWAS analysis of low (<2.5 kg) and high (>4.5 kg) birthweight in the UK Biobank using REGENIE software (Nlow=20,947; Nhigh=12,715; Ncontrols=207,506) and conducted three continuous GWAS of birthweight, one including the full range of birthweights, one involving a truncated GWAS including only individuals with birthweights between 2.5 and 4.5 kg and a third GWAS that winsorised birthweight values <2.5 kg and >4.5 kg. Additionally, we performed bivariate linkage disequilibrium (LD) score regression to estimate the genetic correlation between low/normal/high birthweight and cardiometabolic traits.

RESULTS

Bivariate LD score regression analyses suggested that high birthweight had a mostly similar genetic aetiology to birthweight within the normal range (genetic correlation coefficient [rG]=0.91, 95% CI 0.83, 0.99), whereas there was more evidence for a separate set of genes underlying low birthweight (rG=-0.74, 95% CI 0.66, 0.82). Low birthweight was also significantly positively genetically correlated with most cardiometabolic traits and diseases we examined, whereas high birthweight was mostly positively genetically correlated with adiposity and anthropometric-related traits. The winsorisation strategy performed best in terms of locus detection, with the number of independent genome-wide significant associations (p<5×10-8) increasing from 120 genetic variants at 94 loci in the truncated GWAS to 270 genetic variants at 178 loci, including 27 variants at 25 loci that had not been identified in previous birthweight GWAS. This included a novel low-frequency missense variant in the ABCC8 gene, a gene known to be involved in congenital hyperinsulinism, neonatal diabetes mellitus and MODY, that was estimated to be responsible for a 170 g increase in birthweight amongst carriers.

CONCLUSIONS/INTERPRETATION

Our results underscore the importance of genetic factors in the genesis of the phenotypic correlation between birthweight and cardiometabolic traits and diseases.

Understanding the Genetic Landscape of Gestational Diabetes: Insights into the Causes and Consequences of Elevated Glucose Levels in Pregnancy

Background/Objectives: During pregnancy, physiological changes in maternal circulating glucose levels and its metabolism are essential to meet maternal and fetal energy demands. Major changes in glucose metabolism occur throughout pregnancy and consist of higher insulin resistance and a compensatory increase in insulin secretion to maintain glucose homeostasis. For some women, this change is insufficient to maintain normoglycemia, leading to gestational diabetes mellitus (GDM), a condition characterized by maternal glucose intolerance and hyperglycaemia first diagnosed during the second or third trimester of pregnancy. GDM is diagnosed in approximately 14.0% of pregnancies globally, and it is often associated with short- and long-term adverse health outcomes in both mothers and offspring. Although recent studies have highlighted the role of genetic determinants in the development of GDM, research in this area is still lacking, hindering the development of prevention and treatment strategies. Methods: In this paper, we review recent advances in the understanding of genetic determinants of GDM and glycaemic traits during pregnancy. Results/Conclusions: Our review highlights the need for further collaborative efforts as well as larger and more diverse genotyped pregnancy cohorts to deepen our understanding of the genetic aetiology of GDM, address research gaps, and further improve diagnostic and treatment strategies.

Maternal pre-pregnancy body mass index and risk of preterm birth: a collaboration using large routine health datasets

BACKGROUND

Preterm birth (PTB) is a leading cause of child morbidity and mortality. Evidence suggests an increased risk with both maternal underweight and obesity, with some studies suggesting underweight might be a greater factor in spontaneous PTB (SPTB) and that the relationship might vary by parity. Previous studies have largely explored established body mass index (BMI) categories. Our aim was to compare associations of maternal pre-pregnancy BMI with any PTB, SPTB and medically indicated PTB (MPTB) among nulliparous and parous women across populations with differing characteristics, and to identify the optimal BMI with lowest risk for these outcomes.

METHODS

We used three UK datasets, two USA datasets and one each from South Australia, Norway and Denmark, together including just under 29 million pregnancies resulting in a live birth or stillbirth after 24 completed weeks gestation. Fractional polynomial multivariable logistic regression was used to examine the relationship of maternal BMI with any PTB, SPTB and MPTB, among nulliparous and parous women separately. The results were combined using a random effects meta-analysis. The estimated BMI at which risk was lowest was calculated via differentiation and a 95% confidence interval (CI) obtained using bootstrapping.

RESULTS

We found non-linear associations between BMI and all three outcomes, across all datasets. The adjusted risk of any PTB and MPTB was elevated at both low and high BMIs, whereas the risk of SPTB was increased at lower levels of BMI but remained low or increased only slightly with higher BMI. In the meta-analysed data, the lowest risk of any PTB was at a BMI of 22.5 kg/m2 (95% CI 21.5, 23.5) among nulliparous women and 25.9 kg/m2 (95% CI 24.1, 31.7) among multiparous women, with values of 20.4 kg/m2 (20.0, 21.1) and 22.2 kg/m2 (21.1, 24.3), respectively, for MPTB; for SPTB, the risk remained roughly largely constant above a BMI of around 25-30 kg/m2 regardless of parity.

CONCLUSIONS

Consistency of findings across different populations, despite differences between them in terms of the time period covered, the BMI distribution, missing data and control for key confounders, suggests that severe under- and overweight may play a role in PTB risk.

Reference Values for Birth Weight in Relation to Gestational Age in Poland and Comparison with the Global Percentile Standards

INTRODUCTION

Percentiles of birth weight by gestational age (GA) are an essential tool for clinical assessment and initiating interventions to reduce health risks. Unfortunately, Poland lacks a reference chart for assessing newborn growth based on the national population. This study aimed to establish a national reference range for birth weight percentiles among newborns from singleton deliveries in Poland. Additionally, we sought to compare these percentile charts with the currently used international standards, INTERGROWTH-21 and WHO.

MATERIALS AND METHODS

All singleton live births (n = 3,745,239) reported in Poland between 2010 and 2019 were analyzed. Using the Lambda Mu Sigma (LMS) method, the Generalized Additive Models for Location Scale, and Shape (GAMLSS) package, smoothed percentile charts (3-97) covering GA from 23 to 42 weeks were constructed.

RESULTS

The mean birth weight of boys was 3453 ± 540 g, and this was higher compared with that of girls (3317 ± 509 g). At each gestational age, boys exhibited higher birth weights than girls. The weight range between the 10th and 90th percentiles was 1061 g for boys and 1016 g for girls. Notably, the birth weight of Polish newborns was higher compared to previously published international growth standards.

CONCLUSION

The reference values for birth weight percentiles established in this study for Polish newborns differ from the global standards and are therefore useful for evaluating the growth of newborns within the national population. These findings hold clinical importance in identifying neonates requiring postbirth monitoring.

The association of intrauterine and postnatal growth patterns and nutritional status with toddler body composition

BACKGROUND

Growth patterns may be indicative of underlying changes in body composition. However, few studies have assessed the association of growth and body composition in poorly resourced regions experiencing the double-burden of malnutrition exists. Thus, the aims of this study were to investigate the association of intrauterine and postnatal growth patterns with infant body composition at 2 years in a middle-income country.

METHODS

Participants were from the International Atomic Energy Agency Multicentre Body Composition Reference study. Fat mass (FM), fat free mass (FFM), Fat mass index (FMI), fat free mass index (FFMI), and percentage fat mass (%FM) were measured in 113 infants (56 boys and 57 girls), from Soweto, South Africa, using deuterium dilution from 3 to 24 months. Birthweight categories were classified using the INTERGROWTH-21 standards as small (SGA), appropriate (AGA), and large-for gestational age (LGA). Stunting (> -2 SDS) was defined using the WHO child growth standards. Birthweight z-score, conditional relative weight and conditional length at 12 and 24 mo were regressed on body composition at 24 mo.

RESULTS

There were no sex differences in FM, FFM, FMI and FFMI between 3 and 24 mo. SGA and AGA both had significantly higher %FM than LGA at 12 mo. LGA had higher FM at 24 mo. Children with stunting had lower FM (Mean = 1.94, 95% CI; 1.63-2.31) and FFM (Mean = 5.91, 95% CI; 5.58-6.26) at 12 mo than non-stunting, while the reverse was true for FFMI (Mean = 13.3, 95% CI; 12.5-14.2) at 6 mo. Birthweight and conditionals explained over 70% of the variance in FM. CRW at both 12 and 24 mo was positively associated with FM and FMI. CRW at 12 mo was also positively associated with FMI, while CH at 24 mo was negatively associated with both FFMI and FMI in boys.

CONCLUSION

Both LGA and SGA were associated with higher body fat suggesting that both are disadvantaged nutritional states, likely to increase the risk of obesity. Growth patterns through infancy and toddler period (1-2 years) are indicative of body fat, while growth patterns beyond infancy are less indicative of fat-free mass.

Pre-pregnancy body mass index and risk of maternal or infant complications with gestational diabetes mellitus as a mediator: A multicenter, longitudinal cohort study in China

AIMS

We explored the complex relationships between pre-pregnancy body mass index (pBMI) and maternal or infant complications and the mediating role of gestational diabetes mellitus (GDM) in these relationships.

METHODS

Pregnant women from 24 hospitals in 15 different provinces of China were enrolled in 2017 and followed through 2018. Propensity score-based inverse probability of treatment weighting, logistic regression, restricted cubic spline models, and causal mediation analysis were utilized. In addition, the E-value method was used to evaluate unmeasured confounding factors.

RESULTS

A total of 6174 pregnant women were finally included. Compared to women with a normal pBMI, obese women had a higher risk for gestational hypertension (odds ratio [OR] = 5.38, 95% confidence interval [CI]: 3.48-8.34), macrosomia (OR = 2.65, 95% CI: 1.83-3.84), and large for gestational age (OR = 2.05, 95% CI: 1.45-2.88); 4.73% (95% CI: 0.57%-8.88%), 4.61% (95% CI: 0.51%-9.74%), and 5.02% (95% CI: 0.13%-10.18%) of the associations, respectively, were mediated by GDM. Underweight women had a high risk for low birth weight (OR = 1.42, 95% CI: 1.15-2.08) and small for gestational age (OR = 1.62, 95% CI: 1.23-2.11). Dose-response analyses indicated that 21.0 kg/m² may be the appropriate tipping point pBMI for risk for maternal or infant complications in Chinese women.

CONCLUSION

A high or low pBMI is associated with the risk for maternal or infant complications and partly mediated by GDM. A lower pBMI cutoff of 21 kg/m² may be appropriate for risk for maternal or infant complications in pregnant Chinese women.

Early-life determinants of childhood plasma insulin levels: implications for primordial prevention of diabetes

BACKGROUND

We earlier reported prematurity as an independent risk factor for elevated insulin levels. Investigation is still lacking on the influence of prenatal and perinatal factors on childhood insulin levels.

METHODS

In this secondary analysis of a prospective birth cohort, plasma insulin levels were measured at birth and early childhood. Regression models identified early-life factors associated with the primary outcome: log-transformed childhood plasma insulin levels.

RESULTS

One thousand one hundred and nine children had insulin levels at birth and 825 at both time points. Compared to term, preterm infants had higher plasma insulin levels (geometric mean) at birth (612, 95% CI 552-679 vs. 372, 95% CI 345-402 pmol/ml) and in early childhood (547, 95% CI 494-605 vs. 445, 95% CI 417-475 pmol/ml). Factors associated with higher early childhood insulin levels included higher insulin level at birth, black race, female sex, maternal smoking during pregnancy, maternal perceived stress, in utero drug exposure, maternal pregestational diabetes mellitus, and maternal preconception overweight and obesity.

CONCLUSIONS

In this high-risk US birth cohort, we identified multiple prenatal and perinatal risk factors for higher early childhood insulin levels, in addition to prematurity. These findings lend support to primordial preventive strategies for diabetes mellitus.

IMPACT

In this secondary analysis of a large prospective study from a high-risk racially diverse cohort, we identify biological and social factors that contribute to elevated levels of plasma insulin in early childhood. Our study also investigates factors affecting plasma insulin in preterm infants along with comorbidities commonly seen during the neonatal intensive care stay. Our work reaffirms the importance of Developmental Origins of Health and Disease with regards to in utero programming of insulin levels. Our work supports the possibility that primordial preventive strategies for diabetes mellitus in high-risk populations may need to begin as early as the prenatal period.

Childhood obesity and adverse cardiometabolic risk in large for gestational age infants and potential early preventive strategies: a narrative review

Accumulating evidence indicates that obesity and cardiometabolic risks become established early in life due to developmental programming and infants born as large for gestational age (LGA) are particularly at risk. This review summarizes the recent literature connecting LGA infants and early childhood obesity and cardiometabolic risk and explores potential preventive interventions in early infancy. With the rising obesity rates in women of childbearing age, the LGA birth rate is about 10%. Recent literature continues to support the higher rates of obesity in LGA infants. However, there is a knowledge gap for their lifetime risk for adverse cardiometabolic outcomes. Potential factors that may modify the risk in early infancy include catch-down early postnatal growth, reduction in body fat growth trajectory, longer breastfeeding duration, and presence of a healthy gut microbiome. The early postnatal period may be a critical window of opportunity for active interventions to mitigate or prevent obesity and potential adverse metabolic consequences in later life. A variety of promising candidate biomarkers for the early identification of metabolic alterations in LGA infants is also discussed. IMPACT: LGA infants are the greatest risk category for future obesity, especially if they experience rapid postnatal growth during infancy. Potential risk modifying secondary prevention strategies in early infancy in LGA infants include catch-down early postnatal growth, reduction in body fat growth trajectory, longer breastfeeding duration, and presence of a healthy gut microbiome. LGA infants may be potential low-hanging fruit targets for early preventive interventions in the fight against childhood obesity.

Maternal High-Fat Diet and Offspring Hypertension

The incidence of hypertension has increased to epidemic levels in the past decades. Increasing evidence reveals that maternal dietary habits play a crucial role in the development of hypertension in adult offspring. In humans, increased fat consumption has been considered responsible for obesity and associated diseases. Maternal diets rich in saturated fats have been widely employed in animal models to study various adverse offspring outcomes. In this review, we discussed current evidence linking maternal high-fat diet to offspring hypertension. We also provided an in-depth overview of the potential mechanisms underlying hypertension of developmental origins that are programmed by maternal high-fat intake from animal studies. Furthermore, this review also presented an overview of how reprogramming interventions can prevent maternal high-fat-diet-induced hypertension in adult offspring. Overall, recent advances in understanding mechanisms behind programming and reprogramming of maternal high-fat diet on hypertension of developmental origins might provide the answers to curtail this epidemic. Still, more research is needed to translate research findings into practice.

Maternal Pre-Pregnancy Obesity and Gestational Diabetes Mellitus Increase the Risk of Childhood Obesity

Previous studies have shown inconsistent results regarding the effects of maternal gestational diabetes mellitus (GDM) and pre-pregnancy obesity (PPO) on childhood obesity. This study aimed to determine the risk for early childhood obesity based on maternal GDM and PPO. This nationwide study used data obtained from the National Health Information Database in South Korea. The participants were divided into four groups based on maternal GDM and PPO, and 1:1 matching was performed. Each group had 1319 participants. A generalized estimating equation model was used to analyze the changes in body mass index percentile of children with age, and simple and multiple conditional logistic regression models were used to compare the prevalence of childhood obesity at 5 years. Children whose mothers had both PPO and GDM, only PPO, or only GDM had a 4.46 (95% CI: 3.28−6.05, p < 0.001), 3.11 (95% CI: 2.27−4.26, p < 0.001), or 1.58 (95% CI: 1.12−2.23, p = 0.010) times higher risk, respectively, of developing childhood obesity than children whose mothers had neither PPO nor GDM. Maternal PPO increases the risk for childhood obesity to a higher degree than maternal GDM, and the presence of both increases the risk even further.

Childhood body size directly increases type 1 diabetes risk based on a lifecourse Mendelian randomization approach

The rising prevalence of childhood obesity has been postulated as an explanation for the increasing rate of individuals diagnosed with type 1 diabetes (T1D). In this study, we use Mendelian randomization (MR) to provide evidence that childhood body size has an effect on T1D risk (OR = 2.05 per change in body size category, 95% CI = 1.20 to 3.50, P = 0.008), which remains after accounting for body size at birth and during adulthood using multivariable MR (OR = 2.32, 95% CI = 1.21 to 4.42, P = 0.013). We validate this direct effect of childhood body size using data from a large-scale T1D meta-analysis based on n = 15,573 cases and n = 158,408 controls (OR = 1.94, 95% CI = 1.21 to 3.12, P = 0.006). We also provide evidence that childhood body size influences risk of asthma, eczema and hypothyroidism, although multivariable MR suggested that these effects are mediated by body size in later life. Our findings support a causal role for higher childhood body size on risk of being diagnosed with T1D, whereas its influence on the other immune-associated diseases is likely explained by a long-term effect of remaining overweight for many years over the lifecourse.

The rise in type 1 diabetes is thought to be related to increased childhood obesity, but this relationship is not well understood. In this study, the authors utilize Mendelian randomization to separate the direct and indirect effects of childhood body size on risk of type 1 diabetes and 7 other immune-associated disease outcomes.

Association between maternal prepregnancy body mass index with offspring cardiometabolic risk factors: analysis of three Brazilian birth cohorts

Evidence suggests that maternal prepregnancy body mass index (BMI) is associated with offspring cardiometabolic risk factors. This study was aimed at assessing the association of maternal prepregnancy BMI with offspring cardiometabolic risk factors in adolescence and adulthood. We also evaluated whether offspring BMI was a mediator in this association. The study included mother-offspring pairs from three Pelotas birth cohorts. Offspring cardiometabolic risk factors were collected in the last follow-up of each cohort [mean age (in years) 30.2, 22.6, 10.9]. Blood pressure was measured using an automatic device, cholesterol by using an enzymatic colorimetric method, and glucose from fingertip blood, using a portable glucose meter. In a pooled analysis of the cohorts, multiple linear regression was used to control for confounding. Mediation analysis was conducted using G-computation formula. In the adjusted model, mean systolic blood pressure of offspring from overweight and obese mothers was on average 1.25 (95% CI: 0.45; 2.05) and 2.13 (95% CI: 0.66; 3.59) mmHg higher than that of offspring from normal-weight mothers; for diastolic blood pressure, the means were 0.80 (95% CI: 0.26; 1.34) and 2.60 (95% CI: 1.62; 3.59) mmHg higher, respectively. Non-HDL cholesterol was positively associated with maternal BMI, whereas blood glucose was not associated. Mediation analyses showed that offspring BMI explained completely the association of maternal prepregnancy BMI with offspring systolic and diastolic blood pressure, and non-HDL cholesterol. Our findings suggest that maternal prepregnancy BMI is positively associated with offspring blood pressure, and blood lipids, and this association is explained by offspring BMI.

Exploring the causal effect of maternal pregnancy adiposity on offspring adiposity: Mendelian randomisation using polygenic risk scores

BACKGROUND

Greater maternal adiposity before or during pregnancy is associated with greater offspring adiposity throughout childhood, but the extent to which this is due to causal intrauterine or periconceptional mechanisms remains unclear. Here, we use Mendelian randomisation (MR) with polygenic risk scores (PRS) to investigate whether associations between maternal pre-/early pregnancy body mass index (BMI) and offspring adiposity from birth to adolescence are causal.

METHODS

We undertook confounder adjusted multivariable (MV) regression and MR using mother-offspring pairs from two UK cohorts: Avon Longitudinal Study of Parents and Children (ALSPAC) and Born in Bradford (BiB). In ALSPAC and BiB, the outcomes were birthweight (BW; N = 9339) and BMI at age 1 and 4 years (N = 8659 to 7575). In ALSPAC only we investigated BMI at 10 and 15 years (N = 4476 to 4112) and dual-energy X-ray absorptiometry (DXA) determined fat mass index (FMI) from age 10-18 years (N = 2659 to 3855). We compared MR results from several PRS, calculated from maternal non-transmitted alleles at between 29 and 80,939 single nucleotide polymorphisms (SNPs).

RESULTS

MV and MR consistently showed a positive association between maternal BMI and BW, supporting a moderate causal effect. For adiposity at most older ages, although MV estimates indicated a strong positive association, MR estimates did not support a causal effect. For the PRS with few SNPs, MR estimates were statistically consistent with the null, but had wide confidence intervals so were often also statistically consistent with the MV estimates. In contrast, the largest PRS yielded MR estimates with narrower confidence intervals, providing strong evidence that the true causal effect on adolescent adiposity is smaller than the MV estimates (Pdifference = 0.001 for 15-year BMI). This suggests that the MV estimates are affected by residual confounding, therefore do not provide an accurate indication of the causal effect size.

CONCLUSIONS

Our results suggest that higher maternal pre-/early-pregnancy BMI is not a key driver of higher adiposity in the next generation. Thus, they support interventions that target the whole population for reducing overweight and obesity, rather than a specific focus on women of reproductive age.

Metabolic profiling in early pregnancy and associated factors of folate supplementation: A cross-sectional study

BACKGROUND

Pregnancy generally alters the balance of maternal metabolism, but the molecular profiles in early pregnancy and associated factors of folate supplementation in pregnant women remains incompletely understood.

METHODS

Untargeted metabonomics based on high-performance liquid chromatography-high-resolution mass spectrometry integrated with multivariate metabolic pathway analysis were applied to characterize metabolite profiles and associated factors of folate supplements in early pregnancy. The metabolic baseline of early pregnancy was determined by metabolic analysis of 510 serum samples from 131 non-pregnant and 379 pregnant healthy Chinese women. The pathophysiology of adaptive reactions and metabolic challenges induced by folate supplementation in early pregnancy was further compared between pregnant women with (n = 168) and without (n = 184) folate supplements.

RESULTS

Compared with non-pregnant participants, 106 metabolites, majority of which are related to amino acids and lysophosphatidylcholine/phosphatidylcholine, and 13 metabolic pathways were significantly changed in early pregnancy. The supplementation of folate in early pregnancy induced marked changes in N-acyl ethanolamine 22:0, N-acyl taurine 18:2, glycerophosphoserine 44:1 and 8,11,14-eicosatrienoate, proline, and aminoimidazole ribotide levels.

CONCLUSIONS

During early pregnancy, the metabolism of amino acids significantly changes to meet the physiological requirements of pregnant women. Folate intake may change glucose and lipid metabolism. These findings provide a comprehensive landscape for understanding the basic characteristics and gestational metabolic networks of early pregnancy and folate supplementation. This study provides a basis for further research into the relationship between metabolic markers and pregnancy diseases.

TRIAL REGISTRATION

This study protocol was registered on www.ClinicalTrials.gov, NCT03651934, on August 29, 2018 (prior to recruitment).

Size for gestational age affects the risk for type 1 diabetes in children and adolescents: a Swedish national case-control study

AIM/HYPOTHESIS

Environmental factors are believed to contribute to the risk of developing type 1 diabetes. The aim of this study was to investigate how size for gestational age affects the risk of developing childhood type 1 diabetes.

METHODS

Using the Swedish paediatric diabetes quality register and the Swedish medical birth register, children with type 1 diabetes diagnosed between 2000 and 2012 (n = 9376) were matched with four control children (n = 37,504). Small for gestational age (SGA) and large for gestational age (LGA) were defined according to Swedish national standards. Data were initially analysed using Pearson's χ² and thereafter by single and multiple logistic regression models.

RESULTS

An equal proportion of children were born appropriate for gestational age, but children with type 1 diabetes were more often born LGA and less often born SGA than control children (4.7% vs 3.5% and 2.0% vs 2.6%, respectively, p < 0.001). In the multiple logistic regression analysis, being born LGA increased (adjusted OR 1.16 [95% CI 1.02, 1.32]) and SGA decreased (adjusted OR 0.76 [95% CI 0.63, 0.92]) the risk for type 1 diabetes, regardless of maternal BMI and diabetes.

CONCLUSIONS/INTERPRETATION

Size for gestational age of Swedish children affects the risk of type 1 diabetes, with increased risk if the child is born LGA and decreased risk if the child is born SGA. Being born LGA is an independent risk factor for type 1 diabetes irrespective of maternal BMI and diabetes. Thus, reducing the risk for a child being born LGA might to some extent reduce the risk for type 1 diabetes.

Fasudil alleviated insulin resistance through promotion of proliferation, attenuation of cell apoptosis and inflammation and regulation of RhoA/Rho kinase/insulin/nuclear factor-κB signalling pathway in HTR-8/SVneo cells

OBJECTIVES

The aim of this study was to evaluate the effects of fasudil on insulin resistance (IR) in HTR-8/SVneo cells.

METHODS

HTR-8/SVneo cells were treated with insulin or/and fasudil. Cell proliferation, apoptosis, inflammation and related signalling pathways were assessed.

KEY FINDINGS

Insulin treatment significantly enhanced the protein expressions of RhoA and Rho kinase (ROCK1 and ROCK2), but decreased glucose consumption. Administration of fasudil effectively promoted glucose uptake. Moreover, fasudil enhanced cell viability and the level of proliferating cell nuclear antigen (PCNA). Insulin-mediated cell apoptosis was inhibited by fasudil via the down-regulation of bax and cleaved-caspase-3, and the up-regulation of bcl-2. At the same time, fasudil led to the reduction of IL-1β, TNF-α, IL-6 and IL-8 mRNA levels in insulin-treated cells. In addition, RhoA, ROCK2 and phosphorylated myosin phosphatase target subunit-1 (p-MYPT-1) expressions were down-regulated by fasudil. Importantly, fasudil activated insulin receptor substrate-1 (IRS-1) through increasing p-IRS-1 (Tyr612) and p-Akt expressions. The nuclear NF-κB p65 and p-IκB-α levels were reduced via the administration of fasudil in insulin-treated cells.

CONCLUSIONS

Fasudil mitigated IR by the promotion of cell proliferation, inhibition of apoptosis and inflammation and regulation of RhoA/ROCK/insulin/NF-κB signalling pathway through in vitro studies.

Metabolic profile during pregnancy in BRISA birth cohorts of Ribeirão Preto and São Luís, Brazil

During pregnancy, metabolic changes that develop in women may increase the risk of diseases and conditions that may also harm the life of the growing fetus. The aim of the present study was to identify and compare the metabolic profile (MP) during pregnancy in two birth cohorts in 2010 in the cities of Ribeirão Preto (RP) and São Luís (SL), Brazil. Pregnant women (1393 in RP and 1413 in SL) were studied; information was obtained through questionnaires in addition to anthropometric, biochemical, and blood pressure measurements. Data are presented as means and proportions. To compare the characteristics of pregnant women in both cities, chi-squared and Student's t-tests were applied, with 5% significance level. Ribeirão Preto presented higher mean values than SL for pre-gestational body mass index (24.5 vs 23 kg/m², P<0.001), systolic (108.4 vs 102.8 mmHg, P<0.001) and diastolic (65.9 vs 61.8 mmHg, P<0.001) blood pressure, total cholesterol (226.3 vs 213.7 mg/dL, P<0.001) and fractions, and glycemia (84.5 vs 80.2 mg/dL, P<0.001), except for triglycerides (P=0.135). Women from RP also showed higher rates of pre-gestational overweight and obesity compared with SL (40.1 vs 25.8%). In the present study, pregnant women in RP had a worse gestational metabolic profile than those in SL, with higher pre-gestational excess weight, indicating that nutritional transition was more advanced in the more developed city.

Maternal high-fat diet in mice alters immune regulation and lung function in the offspring

PUFA modulate immune function and have been associated with the risk of childhood atopy and asthma. We investigated the effect of maternal fat intake in mice on PUFA status, elongase and desaturase gene expression, inflammatory markers and lung function in the offspring. C57BL/6J mice (n 32) were fed either standard chow (C, 20·4 % energy as fat) or a high-fat diet (HFD, 39·9 % energy as fat) for 4 weeks prior to conception and during gestation and lactation. At 21 d of age, offspring were weaned onto either the HFD or C, generating four experimental groups: C/C, C/HF, HF/C and HF/HF. Plasma and liver fatty acid composition were measured by GC and gene expression by quantitative PCR. Lung resistance to methacholine was assessed. Arachidonic acid concentrations in offspring plasma and liver phospholipids were increased by HFD; this effect was greater in the post-natal HFD group. DHA concentration in offspring liver phospholipids was increased in response to HFD and was higher in the post-natal HFD group. Post-natal HFD increased hepatic fatty acid desaturase (FADS) 2 and elongation of very long-chain fatty acid 5 expression in male offspring, whereas maternal HFD elevated expression of FADS1 and FADS2 in female offspring compared with males. Post-natal HFD increased expression of IL-6 and C-C motif chemokine ligand 2 (CCL2) in perivascular adipose tissue. The HFD lowered lung resistance to methacholine. Excessive maternal fat intake during development modifies hepatic PUFA status in offspring through regulation of gene expression of enzymes that are involved in PUFA biosynthesis and modifies the development of the offspring lungs leading to respiratory dysfunction.

Maternal Gestational Diabetes Mellitus Modifies the Relationship Between Genetically Determined Body Mass Index During Pregnancy and Childhood Obesity

OBJECTIVE

To analyze the interactions between maternal gestational diabetes mellitus (GDM) and genetically determined maternal body mass index (BMI) during pregnancy on offspring childhood obesity.

RESEARCH DESIGN AND METHODS

A total of 1114 Chinese mother-child pairs (560 GDM and 554 non-GDM) were included between August 2009 and July 2011. Maternal genetic risk score (GRS) of BMI during pregnancy was derived on the basis of 12 single nucleotide polymorphisms identified from a genome-wide association study. Offspring's BMI, BMI-for-age z score, weight, weight-for-age z score, waist circumference, sum of skinfolds, and body fat percentage during childhood were measured or calculated.

RESULTS

Maternal GRS of BMI during pregnancy significantly interacted with maternal GDM status on childhood risks of overweight and obesity (all P for interaction <.05). After multivariable adjustment, per unit of GRS was associated with a 24% (P<.001) and a 28% (P<.001) increased risk of overweight and obesity among children of GDM mothers, whereas no significant associations were observed among children of mothers without GDM. In addition, per unit GRS of BMI during pregnancy was significantly associated with 0.16 kg/m2 higher BMI (P=.002), 0.09 higher BMI-for-age z score (P=.002), 0.24 kg higher weight (P=.04), 0.06 higher weight-for-age z score (P=.02), 0.28 cm higher waist circumference (P=.03), 0.94 mm higher sum of skinfolds (P=.004), and 0.37% higher body fat percentage (P=.03) among children of GDM mothers. There were no significant associations between maternal GRS of BMI during pregnancy and offspring's obesity-related outcomes among children of mothers without GDM.

CONCLUSION

Our findings for the first time indicate that maternal GDM status may modify the relation between genetically determined maternal BMI during pregnancy and offspring's obesity risk during childhood.

Dissecting maternal and fetal genetic effects underlying the associations between maternal phenotypes, birth outcomes, and adult phenotypes: A mendelian-randomization and haplotype-based genetic score analysis in 10,734 mother-infant pairs

BACKGROUND

Many maternal traits are associated with a neonate's gestational duration, birth weight, and birth length. These birth outcomes are subsequently associated with late-onset health conditions. The causal mechanisms and the relative contributions of maternal and fetal genetic effects behind these observed associations are unresolved.

METHODS AND FINDINGS

Based on 10,734 mother-infant duos of European ancestry from the UK, Northern Europe, Australia, and North America, we constructed haplotype genetic scores using single-nucleotide polymorphisms (SNPs) known to be associated with adult height, body mass index (BMI), blood pressure (BP), fasting plasma glucose (FPG), and type 2 diabetes (T2D). Using these scores as genetic instruments, we estimated the maternal and fetal genetic effects underlying the observed associations between maternal phenotypes and pregnancy outcomes. We also used infant-specific birth weight genetic scores as instrument and examined the effects of fetal growth on pregnancy outcomes, maternal BP, and glucose levels during pregnancy. The maternal nontransmitted haplotype score for height was significantly associated with gestational duration (p = 2.2 × 10-4). Both maternal and paternal transmitted height haplotype scores were highly significantly associated with birth weight and length (p < 1 × 10-17). The maternal transmitted BMI scores were associated with birth weight with a significant maternal effect (p = 1.6 × 10-4). Both maternal and paternal transmitted BP scores were negatively associated with birth weight with a significant fetal effect (p = 9.4 × 10-3), whereas BP alleles were significantly associated with gestational duration and preterm birth through maternal effects (p = 3.3 × 10-2 and p = 4.5 × 10-3, respectively). The nontransmitted haplotype score for FPG was strongly associated with birth weight (p = 4.7 × 10-6); however, the glucose-increasing alleles in the fetus were associated with reduced birth weight through a fetal effect (p = 2.2 × 10-3). The haplotype scores for T2D were associated with birth weight in a similar way but with a weaker maternal effect (p = 6.4 × 10-3) and a stronger fetal effect (p = 1.3 × 10-5). The paternal transmitted birth weight score was significantly associated with reduced gestational duration (p = 1.8 × 10-4) and increased maternal systolic BP during pregnancy (p = 2.2 × 10-2). The major limitations of the study include missing and heterogenous phenotype data in some data sets and different instrumental strength of genetic scores for different phenotypic traits.

CONCLUSIONS

We found that both maternal height and fetal growth are important factors in shaping the duration of gestation: genetically elevated maternal height is associated with longer gestational duration, whereas alleles that increase fetal growth are associated with shorter gestational duration. Fetal growth is influenced by both maternal and fetal effects and can reciprocally influence maternal phenotypes: taller maternal stature, higher maternal BMI, and higher maternal blood glucose are associated with larger birth size through maternal effects; in the fetus, the height- and metabolic-risk-increasing alleles are associated with increased and decreased birth size, respectively; alleles raising birth weight in the fetus are associated with shorter gestational duration and higher maternal BP. These maternal and fetal genetic effects may explain the observed associations between the studied maternal phenotypes and birth outcomes, as well as the life-course associations between these birth outcomes and adult phenotypes.

Large-for-gestational-age phenotypes and obesity risk in adulthood: a study of 195,936 women

While there is evidence that being born large-for-gestational-age (LGA) is associated with an increased risk of obesity later in life, the data are conflicting. Thus, we aimed to examine the associations between proportionality at birth and later obesity risk in adulthood. This was a retrospective study using data recorded in the Swedish Birth Register. Anthropometry in adulthood was assessed in 195,936 pregnant women at 10-12 weeks of gestation. All women were born at term (37-41 weeks of gestation). LGA was defined as birth weight and/or length ≥2.0 SDS. Women were separated into four groups: appropriate-for-gestational-age according to both weight and length (AGA - reference group; n = 183,662), LGA by weight only (n = 4,026), LGA by length only (n = 5,465), and LGA by both weight and length (n = 2,783). Women born LGA based on length, weight, or both had BMI 0.12, 1.16, and 1.08 kg/m² greater than women born AGA, respectively. The adjusted relative risk (aRR) of obesity was 1.50 times higher for those born LGA by weight and 1.51 times for LGA by both weight and height. Length at birth was not associated with obesity risk. Similarly, women born LGA by ponderal index had BMI 1.0 kg/m² greater and an aRR of obesity 1.39 times higher than those born AGA. Swedish women born LGA by weight or ponderal index had an increased risk of obesity in adulthood, irrespective of their birth length. Thus, increased risk of adult obesity seems to be identifiable from birth weight and ignoring proportionality.

Maternal postload 1-hour glucose level during pregnancy and offspring's overweight/obesity status in preschool age

BACKGROUND

Childhood obesity is associated with adverse outcomes such as metabolic syndrome, diabetes, and cardiovascular diseases in adulthood. Identifying risk factors related to excessive adiposity in early childhood is of great importance for obesity intervention. The results of studies for associations between maternal with gestational diabetes and offspring obesity are conflicting. Nonetheless, the association of maternal glucose across a spectrum of glucose values with childhood adiposity outcomes is less clear.

AIM

To assess the association of maternal glucose across a spectrum of glucose values with childhood adiposity at age 5 years.

METHODS

A population-based cohort study was conducted between 2011 and 2018. Using the healthcare records data were from the Medical Birth Registry in Xiamen, China. The primary outcome was offspring obese/obesity. Primary predictors were maternal oral glucose tolerance test values during pregnancy.

RESULTS

6090 mother-child pairs were analyzed. The mean age of the children at follow-up was 5.2 years. At multiple logistic regression, after adjustment for variables, including maternal pre-pregnancy body mass index (BMI), birth weight of offspring, and insulin therapy, ORs for offspring overweight/obesity were 1.13 (95% CI 0.90 to 1.42) for maternal fasting glucose levels, 1.12 (95% CI 1.04 to 1.22) for 1-hour glucose, and 1.04 (95% CI 0.95 to 1.14) for 2-hour glucose. The adjusted association of offspring BMI Z-score with maternal 1-hour glucose level remained significant. There were no significant associations between BMI Z-score and maternal fasting glucose and 2-hour glucose level. Exploratory sex-specific analyses indicated generally consistent associations for boys and girls.

CONCLUSION

Maternal postload 1-hour glucose across a spectrum of glucose values during pregnancy was an independent risk for offspring weight gain at age 5 years, indicating the importance of screen and management of maternal 1-hour glucose level, except for fasting glucose and 2-hour glucose level during pregnancy in order to prevent offspring weight gain in early childhood.

Adverse pregnancy outcomes on the risk of overweight offspring: a population-based retrospective study in Xiamen, China

The growth trajectory of Chinese preschoolers still remains unclear. Our objective was to determine whether there was an association between adverse pregnancy outcomes and overweight offspring. We analyzed population-based retrospective cohort data from the Medical Birth Registry of Xiamen, which comprised 33,157 children examined from 1 to 6 years of age. Longitudinal analyses were used to evaluate the growth trajectories of offspring body mass index (BMI). Multivariate logistic regression was used to assess the effects of two adverse pregnancy outcomes, gestational diabetes mellitus (GDM) and being large-for-gestational age (LGA), on childhood overweight. Offspring of mothers with GDM and LGA has a higher annual BMI z-score from 1 to 6 years of age (all P < 0.05). But, a higher annual BMI z-score was only observed in children aged 1-5 years in models 1-3. Overall BMI z-score of offspring aged 1-6 who were born to mothers with GDM and LGA were also higher in models 1-3 (all P < 0.05). Additionally, offspring of mothers with GDM and LGA had a higher risk for overweight in model 1, from 1 to 6 years of age (odds ratio (OR), 1.814; 95% confidence interval (CI), 1.657-1.985; P < 0.0001). However, this association was attenuated after adjusting for maternal pre-pregnancy BMI (OR, 1.270; 95% CI, 0.961-1.679; P = 0.0930). Offspring of mothers with GDM and LGA had a higher BMI z-score and increased risk for overweight. Indeed, intrauterine exposure to maternal GDM and LGA could bias offspring to overweight, whereas maternal pre-pregnancy BMI may play a key role in offspring overweight for children born to mothers with GDM and LGA.

Epigenetics and gestational diabetes: a review of epigenetic epidemiology studies and their use to explore epigenetic mediation and improve prediction

Epigenetics encapsulates a group of molecular mechanisms including DNA methylation, histone modification and microRNAs (miRNAs). Gestational diabetes (GDM) increases the risk of adverse perinatal outcomes and is associated with future offspring risk of obesity and type 2 diabetes. It has been hypothesised that epigenetic mechanisms mediate an effect of GDM on offspring adiposity and type 2 diabetes and this could provide a modifiable mechanism to reduce type 2 diabetes in the next generation. Evidence for this hypothesis is lacking. Epigenetic epidemiology could also contribute to reducing type 2 diabetes by identifying biomarkers that accurately predict risk of GDM and its associated future adverse outcomes. We reviewed published human studies that explored associations between any of maternal GDM, type 2 diabetes, gestational fasting or post-load glucose and any epigenetic marker (DNA methylation, histone modification or miRNA). Of the 81 relevant studies we identified, most focused on the potential role of epigenetic mechanisms in mediating intrauterine effects of GDM on offspring outcomes. Studies were small (median total number of participants 58; median number of GDM cases 27) and most did not attempt replication. The most common epigenetic measure analysed was DNA methylation. Most studies that aimed to explore epigenetic mediation examined associations of in utero exposure to GDM with offspring cord or infant blood/placenta DNA methylation. Exploration of any causal effect, or effect on downstream offspring outcomes, was lacking. There is a need for more robust methods to explore the role of epigenetic mechanisms as possible mediators of effects of exposure to GDM on future risk of obesity and type 2 diabetes. Research to identify epigenetic biomarkers to improve identification of women at risk of GDM and its associated adverse (maternal and offspring) outcomes is currently rare but could contribute to future tools for accurate risk stratification.

Paternal impact on the life course development of obesity and type 2 diabetes in the offspring

The aetiologies of obesity and type 2 diabetes are incredibly complex, but the potential role of paternal influences remains relatively understudied. A better understanding of paternal influences on offspring risk of obesity and type 2 diabetes could have profound implications for public health, clinical practice and society. In this review, we outline potential biological and social mechanisms through which fathers might exert an impact on the health of their offspring. We also present a systematically compiled overview of the current evidence linking paternal factors to offspring development of obesity and type 2 diabetes throughout the life course. Although evidence is accumulating to support paternal associations with offspring outcomes, more high-quality research is needed to overcome specific methodological challenges and provide stronger causal evidence.

Gestational diabetes mellitus, pre-gestational BMI and offspring BMI z-score during infancy and childhood: 2004 Pelotas Birth Cohort

OBJECTIVE

Gestational diabetes mellitus (GDM) affects a significant number of women. Evidence regarding the association between GDM and offspring body mass index (BMI) is unclear due to small samples and lack of adequate confounding control. The objective of this study was to investigate the association between GDM and offspring BMI z-scores from birth to early adolescence and to examine the role of maternal pre-gestational BMI in this relationship.

DESIGN

Prospective study.

SETTING

Pelotas 2004 Birth Cohort, Brazil.

PARTICIPANTS

Cohort participants that were followed-up from birth up to early adolescence (~3500) and their mothers.

PRIMARY OUTCOME MEASURES

BMI z-scores at birth, 3, 12, 24, 48 months and 6 and 11 years of age, calculated according to the WHO growth charts.

RESULTS

Unadjusted and adjusted linear regressions were performed and interaction terms between maternal pre-gestational BMI and GDM were included. Prevalence of self-reported GDM was 2.6% (95% CI 2.1% to 3.1%). The offspring BMI z-scores (SD) at birth, 3, 12, 24, 48 months and at 6 and 11 years were 0.10 (1.12), -0.47 (1.10), 0.59 (1.10), 0.59 (1.08), 0.78 (1.32), 0.70 (1.43) and 0.75 (1.41), respectively. Unadjusted regression models showed positive associations between GDM and offspring BMI z-scores at birth, 6 and 11 years. After adjustment, the associations attenuated towards the null. Statistical evidence of effect modification between maternal pre-gestational BMI and GDM was observed at birth (p=0.007), with the association between GDM and offspring BMI z-score being apparent only in those children born to overweight or obese mothers (β=0.72, 95% CI 0.30 to 1.14 and β=0.61, 95% CI 0.20 to 1.01, respectively).

CONCLUSIONS

We observed that in the association between GDM and offspring BMI z-scores, there is a predominant role for maternal nutritional status before pregnancy and that the association between GDM and newborn's BMI is apparent only among those born to overweight or obese mothers.

Association of trimester-specific gestational weight gain with birth weight and fetal growth in a large community-based population

BACKGROUND

Previous studies showed that the association of gestational weight gain (GWG) with fetal birthweight and offspring developmental growth was unclear. The aim of this study is to investigate the respective effect of 1 kg of GWG during three trimesters on birthweight and offspring growth from birth to 3 years of age.

METHODS

We extracted the decoded information from the Maternal and Child Health Information Management System of Zhoushan Maternal and Child Health Hospital in Zhejiang, China from October 2001 to March 2015, and used multiple linear and logistic regression models.

RESULTS

This study included 20,232 women with a full-term singleton birth and 15,557 newborns who took regular health check-ups. Compared to that in the 2nd and 3rd trimester, 1 kg GWG increasing in the 1st trimester had the strongest positive association with higher birthweight, body weight, and height from 1 to 36 months. Their associations with BMI after birth were similar among the three trimesters. In addition, some positive dose-response effects found between quartiles of GWG in the 1st trimester and offspring body weight, as well as BMI. The 1 kg GWG in 1st trimester played the strongest role in contributing to birth weight and benefiting to body growth among children aged up to 3 years.

CONCLUSION

The 1 kg GWG in 1st trimester contributed more to birth weight and body development from birth to 3 years compared to the 2nd and 3rd trimesters. The possible beneficial effects of GWG in the 1st trimester on birthweight and offspring development in under/normal weight mothers are found.

Gestational route to healthy birth (GaRBH): protocol for an Indian prospective cohort study

INTRODUCTION

Pregnancy is characterised by a high rate of metabolic shifts from early to late phases of gestation in order to meet the raised physiological and metabolic needs. This change in levels of metabolites is influenced by gestational weight gain (GWG), which is an important characteristic of healthy pregnancy. Inadequate/excessive GWG has short-term and long-term implications on maternal and child health. Exploration of gestational metabolism is required for understanding the quantitative changes in metabolite levels during the course of pregnancy. Therefore, our aim is to study trimester-specific variation in levels of metabolites in relation to GWG and its influence on fetal growth and newborn anthropometric traits at birth.

METHODS AND ANALYSIS

A prospective longitudinal study is planned (start date: February 2018; end date: March 2023) on pregnant women that are being recruited in the first trimester and followed in subsequent trimesters and at the time of delivery (total 3 follow-ups). The study is being conducted in a hospital located in Bikaner district (66% rural population), Rajasthan, India. The estimated sample size is of 1000 mother-offspring pairs. Information on gynaecological and obstetric history, socioeconomic position, diet, physical activity, tobacco and alcohol consumption, depression, anthropometric measurements and blood samples is being collected for metabolic assays in each trimester using standardised methods. Mixed effects regression models will be used to assess the role of gestational weight in influencing metabolite levels in each trimester. The association of maternal levels of metabolites with fetal growth, offspring's weight and body composition at birth will be investigated using regression modelling.

ETHICS AND DISSEMINATION

The study has been approved by the ethics committees of the Department of Anthropology, University of Delhi and Sardar Patel Medical College, Rajasthan. We are taking written informed consent after discussing the various aspects of the study with the participants in the local language.

Impact of maternal body mass index and gestational weight gain on pregnancy complications: an individual participant data meta-analysis of European, North American and Australian cohorts

OBJECTIVE

To assess the separate and combined associations of maternal pre-pregnancy body mass index (BMI) and gestational weight gain with the risks of pregnancy complications and their population impact.

DESIGN

Individual participant data meta-analysis of 39 cohorts.

SETTING

Europe, North America, and Oceania.

POPULATION

265 270 births.

METHODS

Information on maternal pre-pregnancy BMI, gestational weight gain, and pregnancy complications was obtained. Multilevel binary logistic regression models were used.

MAIN OUTCOME MEASURES

Gestational hypertension, pre-eclampsia, gestational diabetes, preterm birth, small and large for gestational age at birth.

RESULTS

Higher maternal pre-pregnancy BMI and gestational weight gain were, across their full ranges, associated with higher risks of gestational hypertensive disorders, gestational diabetes, and large for gestational age at birth. Preterm birth risk was higher at lower and higher BMI and weight gain. Compared with normal weight mothers with medium gestational weight gain, obese mothers with high gestational weight gain had the highest risk of any pregnancy complication (odds ratio 2.51, 95% CI 2.31- 2.74). We estimated that 23.9% of any pregnancy complication was attributable to maternal overweight/obesity and 31.6% of large for gestational age infants was attributable to excessive gestational weight gain.

CONCLUSIONS

Maternal pre-pregnancy BMI and gestational weight gain are, across their full ranges, associated with risks of pregnancy complications. Obese mothers with high gestational weight gain are at the highest risk of pregnancy complications. Promoting a healthy pre-pregnancy BMI and gestational weight gain may reduce the burden of pregnancy complications and ultimately the risk of maternal and neonatal morbidity.

TWEETABLE ABSTRACT

Promoting a healthy body mass index and gestational weight gain might reduce the population burden of pregnancy complications.

Negative control exposure studies in the presence of measurement error: implications for attempted effect estimate calibration

Background

Negative control exposure studies are increasingly being used in epidemiological studies to strengthen causal inference regarding an exposure-outcome association when unobserved confounding is thought to be present. Negative control exposure studies contrast the magnitude of association of the negative control, which has no causal effect on the outcome but is associated with the unmeasured confounders in the same way as the exposure, with the magnitude of the association of the exposure with the outcome. A markedly larger effect of the exposure on the outcome than the negative control on the outcome strengthens inference that the exposure has a causal effect on the outcome.

Methods

We investigate the effect of measurement error in the exposure and negative control variables on the results obtained from a negative control exposure study. We do this in models with continuous and binary exposure and negative control variables using analysis of the bias of the estimated coefficients and Monte Carlo simulations.

Results

Our results show that measurement error in either the exposure or negative control variables can bias the estimated results from the negative control exposure study.

Conclusions

Measurement error is common in the variables used in epidemiological studies; these results show that negative control exposure studies cannot be used to precisely determine the size of the effect of the exposure variable, or adequately adjust for unobserved confounding; however, they can be used as part of a body of evidence to aid inference as to whether a causal effect of the exposure on the outcome is present.

The effect of a lifestyle intervention in obese pregnant women on gestational metabolic profiles: findings from the UK Pregnancies Better Eating and Activity Trial (UPBEAT) randomised controlled trial

BACKGROUND

Pregnancy is associated with widespread change in metabolism, which may be more marked in obese women. Whether lifestyle interventions in obese pregnant women improve pregnancy metabolic profiles remains unknown. Our objectives were to determine the magnitude of change in metabolic measures during obese pregnancy, to indirectly compare these to similar profiles in a general pregnant population, and to determine the impact of a lifestyle intervention on change in metabolic measures in obese pregnant women.

METHODS

Data from a randomised controlled trial of 1158 obese (BMI ≥ 30 kg/m²) pregnant women recruited from six UK inner-city obstetric departments were used. Women were randomised to either the UPBEAT intervention, a tailored complex lifestyle intervention focused on improving diet and physical activity, or standard antenatal care (control group). UPBEAT has been shown to improve diet and physical activity during pregnancy and up to 6-months postnatally in obese women and to reduce offspring adiposity at 6-months; it did not affect risk of gestational diabetes (the primary outcome). Change in the concentrations of 158 metabolic measures (129 lipids, 9 glycerides and phospholipids, and 20 low-molecular weight metabolites), quantified three times during pregnancy, were compared using multilevel models. The role of chance was assessed with a false discovery rate of 5% adjusted p values.

RESULTS

All very low-density lipoprotein (VLDL) particles increased by 1.5-3 standard deviation units (SD) whereas intermediate density lipoprotein and specific (large, medium and small) LDL particles increased by 1-2 SD, between 16 and 36 weeks' gestation. Triglycerides increased by 2-3 SD, with more modest changes in other metabolites. Indirect comparisons suggest that the magnitudes of change across pregnancy in these obese women were 2- to 3-fold larger than in unselected women (n = 4260 in cross-sectional and 583 in longitudinal analyses) from an independent, previously published, study. The intervention reduced the rate of increase in extremely large, very large, large and medium VLDL particles, particularly those containing triglycerides.

CONCLUSION

There are marked changes in lipids and lipoproteins and more modest changes in other metabolites across pregnancy in obese women, with some evidence that this is more marked than in unselected pregnant women. The UPBEAT lifestyle intervention may contribute to a healthier metabolic profile in obese pregnant women, but our results require replication.

TRIAL REGISTRATION

UPBEAT was registered with Current Controlled Trials, ISRCTN89971375 , on July 23, 2008 (prior to recruitment).

Gestational diabetes mellitus alters DNA methylation profiles in pancreas of the offspring mice

Gestational diabetes mellitus (GDM), which has an increasing global prevalence, contributes to the susceptibility to metabolic dysregulation and obesity in the offspring via epigenetic modifications. However, the underlying mechanism remains largely obscure. The current study established a GDM mice model to investigate the alternations in the metabolic phenotypes and genomic DNA methylation in the pancreas of the offspring. We found that in the GDM offspring, intrauterine hyperglycemia induced dyslipidemia, insulin resistance, and glucose intolerance. Meanwhile, altered DNA methylation patterns were exhibited in the pancreas and many differentially methylated regions (DMRs)-related genes were involved in glycolipids metabolism and related signaling pathways, including Agap2, Plcbr, Hnf1b, Gnas, Fbp2, Cdh13, Wnt2, Kcnq1, Lhcgr, Irx3, etc. Additionally, the overall hypermethylation of Agap2, verified by bisulfite sequencing PCR (BSP), was negatively correlated with its mRNA expression level. In conclusion, these findings suggest that the DNA methylation changes in the pancreatic genome of the GDM offspring may be associated with the glycolipid metabolism abnormalities, T2DM susceptibility, and obesity in the adult GDM offspring.

Maternal gestational diabetes and different indicators of childhood obesity: a large study

Previous studies found conflicting results about the associations between the exposure to hyperglycemia in utero and the later risks of childhood overweight and obesity. The aim of the present study is to compare the children's BMI growth between offspring exposed to maternal gestational diabetes mellitus (GDM) and those not exposed and assess the associations between maternal GDM and their offspring's overweight and obesity risk. We performed a large observational study in 1156 women and their offspring (578 GDM and 578 non-GDM mother-child pairs, matched by their offspring's gender and age). Maternal GDM was diagnosed according to the World Health Organization criteria. Childhood height, weight, waist circumference, body fat and skinfold were measured using standardized methods. After adjustment for maternal and children's characteristics, children born to mothers with GDM during pregnancy had higher mean values of Z scores for BMI-for-age, Z scores for weight-for-age, waist circumferences, body fat, subscapular skinfold and suprailiac skinfold, in comparison with their counterparts born to mothers with normal glucose during pregnancy (all P values <0.05). Moreover, maternal GDM was associated with a higher risk of childhood overweight and obesity with multivariate-adjusted odds ratios of 1.42 (95% confidence interval (CI): 1.02-1.97) and 1.18 (95% CI: 1.11-1.24), respectively, compared with the children of mothers without GDM during pregnancy. This study demonstrates that maternal GDM is an independent risk factor of childhood overweight and obesity and is associated with higher BMI in the offspring.

Gestational diabetes and offspring's growth from birth to 6 years old

OBJECTIVES

The objective of this study was to compare the children's body mass index (BMI) growth between offspring exposed to maternal gestational diabetes mellitus (GDM) and those not exposed, and assess the associations between maternal hyperglycemia and their offspring's overweight risk from 1 to 6 years of age.

METHODS

Using the healthcare records data from the Tianjin Maternal and Child Healthcare System, we conducted a population-based cohort study, which is composed of 27,155 mother-child pairs with all mothers undergoing GDM screening test in pregnancy.

RESULTS

After adjustment for maternal and children's characteristics, children born to mothers with abnormal glucose (including GDM or abnormal glucose challenge test (GCT) but normal oral glucose tolerance test (OGTT) results) during pregnancy had higher mean values of Z-scores for BMI for age at 1, 2, 3, 5, and 6 years of age, in comparison with those born to mothers with normal glucose (all P values < 0.05). Moreover, maternal abnormal glucose was associated with a higher risk of childhood overweight with multivariate-adjusted hazard ratios of 1.07 (95% confidence interval (CI) 1.01-1.14), 1.09 (95% CI 1.04-1.15), 1.10 (95% CI 1.04-1.15), 1.08 (95% CI 1.03-1.14), 1.08 (95% 1.03-1.13), and 1.07 (95% 1.02-1.12) at 1-6 years of age compared with children of mothers with normal glucose.

CONCLUSIONS

Abnormal maternal glucose tolerance during pregnancy was independently associated with children's higher BMI and overweight risk from 1 to 6 years of age. Women with positive GCT results but negative OGTT can be neglected by the health system. More attention should be paid to the health of these mothers and their offspring.

It's the mother!: How assumptions about the causal primacy of maternal effects influence research on the developmental origins of health and disease

Research on the developmental origins of health and disease (DOHaD) has traditionally focused on how maternal exposures around the time of pregnancy might influence offspring health and risk of disease. We acknowledge that for some exposures this is likely to be correct, but argue that the focus on maternal pregnancy effects also reflects implicit and deeply-held assumptions that 1) causal early life exposures are primarily transmitted via maternal traits or exposures, 2) maternal exposures around the time of pregnancy and early infancy are particularly important, and 3) other factors, such as paternal factors and postnatal exposures in later life, have relatively little impact in comparison. These implicit assumptions about the "causal primacy" of maternal pregnancy effects set the agenda for DOHaD research and, through a looping effect, are reinforced rather than tested. We propose practical strategies to redress this imbalance through maintaining a critical perspective about these assumptions.

Absence of Adolescent Obesity in Grenada: Is This a Generational Effect?

Background: Low- and middle-income countries are affected disproportionately by the ongoing global obesity pandemic. Representing a middle income country, the high prevalence of obesity among Grenadian adults as compared to US adults is expected as part of global obesity trends. The objective of this study was to determine if Grenadian adolescents have a higher prevalence of overweight compared to their US counterparts, and if a disparity exists between urban and rural adolescents. Methods: Using a subcohort of participants in the Grenadian Nutrition Student Survey, diet quality and anthropometric measures were collected from 55% of the classrooms of first year secondary students in Grenada (n = 639). Rural or urban designations were given to each school. Body Mass Index (BMI) was calculated and categorized as overweight or obese for each student following CDC classification cutoffs. A standardized BMI (BMIz) was calculated for each school. Sex-specific BMI and overall BMIz were compared to a 1980s US cohort. Multilevel models, overall and stratified by sex, of students nested within schools were conducted to determine if BMIz differed by rural or urban locality, gender, and diet quality. Results: The mean age of this cohort was 12.7 (SD = 0.8) years with 83.8% of the cohort identifying as Afro-Caribbean. Females had nearly twice the prevalence of overweight when compared to males (22.7 vs. 12.2%) but a similar prevalence of obesity (8.2 vs. 6.8%). Grenadian adolescents had lower prevalence of overweight (females: 22.7 vs. 44.7%; males: 12.2 vs. 38.8%, respectively) as compared to US counterparts. Eating a traditional diet was negatively associated with BMIz score among females ( β ^ = -0.395; SE = 0.123) in a stratified, multilevel analysis. BMIz scores did not differ significantly by rural or urban school designation. Conclusions: Among Grenadian adolescents, this study identified a lower overweight prevalence compared to US counterparts and no difference in overweight prevalence by urban or rural location. We hypothesize that the late introduction of processed foods to Grenada protected this cohort from obesogenic promoters due to a lack of fetal overnutrition. However, further research in subsequent birth cohorts is needed to determine if adolescent obesity will increase due to a generational effect.

Newborn weight change and childhood cardio-metabolic traits - a prospective cohort study

Background

Newborn weight change (NWC) in the first 4 days represents short-term adaptations to external environment. It may be a key developmental period for future cardio-metabolic health, but this has not been explored. We aimed to determine the associations of NWC with childhood cardio-metabolic traits.

Methods

As part of Generation XXI birth cohort, children were recruited in 2005/2006 at all public units providing obstetrical and neonatal care in Porto. Birthweight was abstracted from clinical records and postnatal anthropometry was obtained by trained examiners during hospital stay. NWC was calculated as ((minimum weight - birthweight)/birthweight) × 100. At age 4 and 7, children were measured and had a fasting blood sample collected. Fasting glucose, LDL-cholesterol, triglycerides, waist circumference, systolic and diastolic blood pressure were evaluated. This study included 312 children with detailed information on growth in very early life and subsequent cardio-metabolic measures. Path analysis was used to compute adjusted regression coefficients and 95% confidence intervals.

Results

NWC was not associated with any cardio-metabolic traits at ages 4 or 7. Strong associations were observed between each cardio-metabolic trait at 4 with the same trait at 7 years. The strongest associations were found for waist circumference [0.725 (0.657; 0.793)] and LDL-cholesterol [0.655 (0.575; 0.735)].

Conclusions

No evidence that NWC is related to childhood cardio-metabolic traits was found, suggesting that NWC should be faced in clinical practice as a short-term phenomenon, with no medium/long term consequences, at least in cardio-metabolic health. Our results show strong tracking correlations in cardio-metabolic traits during childhood.

Electronic supplementary material

The online version of this article (10.1186/s12887-018-1184-x) contains supplementary material, which is available to authorized users.

Associations Among Obesity, Inflammation, and Tryptophan Catabolism in Pregnancy

OBJECTIVE

To evaluate relationships among obesity in pregnancy and plasma levels of tryptophan (TRP) and kynurenine (KYN), inflammatory markers, and depressed mood.

METHODS

Pregnant women ( N = 374) were enrolled, and data were collected at a mean gestation of 20 weeks in this cross-sectional study. Plasma was analyzed for TRP, KYN, neopterin, and nitrite levels. Women completed demographic and mood scales.

RESULTS

There was a statistically significant inverse correlation between body mass index (BMI) and TRP and positive correlations between BMI and KYN and the kynurenine/tryptophan (KYN/TRP) ratio. Neopterin was correlated with KYN/TRP, suggesting that the indoleamine 2,3-dioxygenase-1 (IDO-1) enzyme was activated. The correlations of neopterin and nitrite with BMI were too small to be clinically meaningful but may provide mechanistic insight. There was a correlation between depressed mood and nitrite levels. Depressed mood was also associated with lower TRP levels. When the sample was divided into pregnant women with or without obesity, TRP was significantly lower and the KYN/TRP ratio was significantly higher in the women with obesity.

CONCLUSION

The pro-inflammatory state of obesity in pregnancy may drive activation of IDO-1, resulting in diversion of TRP away from serotonin and melatonin production and toward KYN metabolites. This alteration could contribute to depression, impaired sleep, increased production of excitotoxic neurotransmitters, and reinforcement of a pro-inflammatory state in pregnancy.

Epigenetic marks of in utero exposure to gestational diabetes and childhood adiposity outcomes: the EPOCH study

AIMS

To identify gestational diabetes mellitus exposure-associated DNA methylation changes and assess whether such changes are also associated with adiposity-related outcomes.

METHODS

We performed an epigenome-wide association analysis, using Illumina 450k methylation arrays, on whole blood collected, on average, at 10.5 years of age from 81 gestational diabetes-exposed and 81 unexposed offspring enrolled in the EPOCH (Exploring Perinatal Outcomes in Children) study, and on the cord blood of 31 gestational diabetes-exposed and 64 unexposed offspring enrolled in the Colorado Healthy Start cohort. Validation was performed by pyrosequencing.

RESULTS

We identified 98 differentially methylated positions associated with gestational diabetes exposure at a false discovery rate of <10% in peripheral blood, with 51 loci remaining significant (plus additional 40 loci) after adjustment for cell proportions. We also identified 2195 differentially methylation regions at a false discovery rate of <5% after adjustment for cell proportions. We prioritized loci for pyrosequencing validation and association analysis with adiposity-related outcomes based on strengths of association and effect size, network and pathway analysis, analysis of cord blood, and previous publications. Methylation in six out of nine (67%) gestational diabetes-associated genes was validated and we also showed that methylation of SH3PXD2A was significantly (P<0.05) associated with multiple adiposity-related outcomes.

CONCLUSIONS

Our findings suggest that epigenetic marks may provide an important link between in utero exposure to gestational diabetes and obesity in childhood, and add to the growing body of evidence that DNA methylation is affected by gestational diabetes exposure.

Maternal and fetal genetic contribution to gestational weight gain

BACKGROUND

Clinical recommendations to limit gestational weight gain (GWG) imply high GWG is causally related to adverse outcomes in mother or offspring, but GWG is the sum of several inter-related complex phenotypes (maternal fat deposition and vascular expansion, placenta, amniotic fluid and fetal growth). Understanding the genetic contribution to GWG could help clarify the potential effect of its different components on maternal and offspring health. Here we explore the genetic contribution to total, early and late GWG.

PARTICIPANTS AND METHODS

A genome-wide association study was used to identify maternal and fetal variants contributing to GWG in up to 10 543 mothers and 16 317 offspring of European origin, with replication in 10 660 mothers and 7561 offspring. Additional analyses determined the proportion of variability in GWG from maternal and fetal common genetic variants and the overlap of established genome-wide significant variants for phenotypes relevant to GWG (for example, maternal body mass index (BMI) and glucose, birth weight).

RESULTS

Approximately 20% of the variability in GWG was tagged by common maternal genetic variants, and the fetal genome made a surprisingly minor contribution to explain variation in GWG. Variants near the pregnancy-specific beta-1 glycoprotein 5 (PSG5) gene reached genome-wide significance (P=1.71 × 10-8) for total GWG in the offspring genome, but did not replicate. Some established variants associated with increased BMI, fasting glucose and type 2 diabetes were associated with lower early, and higher later GWG. Maternal variants related to higher systolic blood pressure were related to lower late GWG. Established maternal and fetal birth weight variants were largely unrelated to GWG.

CONCLUSIONS

We found a modest contribution of maternal common variants to GWG and some overlap of maternal BMI, glucose and type 2 diabetes variants with GWG. These findings suggest that associations between GWG and later offspring/maternal outcomes may be due to the relationship of maternal BMI and diabetes with GWG.

Early Life Exposures and Adult Cancer Risk

Very little is known about the influence of early life exposures on adult cancer risk. The purpose of this narrative review was to summarize the epidemiologic evidence relating early life tobacco use, obesity, diet, and physical activity to adult cancer risk; describe relevant theoretical frameworks and methodological strategies for studying early life exposures; and discuss policies and research initiatives focused on early life. Our findings suggest that in utero exposures may indirectly influence cancer risk by modifying biological pathways associated with carcinogenesis; however, more research is needed to firmly establish these associations. Initiation of exposures during childhood and adolescence may impact cancer risk by increasing duration and lifetime exposure to carcinogens and/or by acting during critical developmental periods. To expand the evidence base, we encourage the use of life course frameworks, causal inference methods such as Mendelian randomization, and statistical approaches such as group-based trajectory modeling in future studies. Further, we emphasize the need for objective exposure biomarkers and valid surrogate endpoints to reduce misclassification. With the exception of tobacco use, there is insufficient evidence to support the development of new cancer prevention policies; however, we highlight existing policies that may reduce the burden of these modifiable risk factors in early life.

The identification and treatment of women with hyperglycaemia in pregnancy: an analysis of individual participant data, systematic reviews, meta-analyses and an economic evaluation

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a higher risk of important adverse outcomes. Practice varies and the best strategy for identifying and treating GDM is unclear.

AIM

To estimate the clinical effectiveness and cost-effectiveness of strategies for identifying and treating women with GDM.

METHODS

We analysed individual participant data (IPD) from birth cohorts and conducted systematic reviews to estimate the association of maternal glucose levels with adverse perinatal outcomes; GDM prevalence; maternal characteristics/risk factors for GDM; and the effectiveness and costs of treatments. The cost-effectiveness of various strategies was estimated using a decision tree model, along with a value of information analysis to assess where future research might be worthwhile. Detailed systematic searches of MEDLINE^® and MEDLINE In-Process & Other Non-Indexed Citations^®, EMBASE, Cumulative Index to Nursing and Allied Health Literature Plus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Health Technology Assessment database, NHS Economic Evaluation Database, Maternity and Infant Care database and the Cochrane Methodology Register were undertaken from inception up to October 2014.

RESULTS

We identified 58 studies examining maternal glucose levels and outcome associations. Analyses using IPD alone and the systematic review demonstrated continuous linear associations of fasting and post-load glucose levels with adverse perinatal outcomes, with no clear threshold below which there is no increased risk. Using IPD, we estimated glucose thresholds to identify infants at high risk of being born large for gestational age or with high adiposity; for South Asian (SA) women these thresholds were fasting and post-load glucose levels of 5.2 mmol/l and 7.2 mmol/l, respectively and for white British (WB) women they were 5.4 and 7.5 mmol/l, respectively. Prevalence using IPD and published data varied from 1.2% to 24.2% (depending on criteria and population) and was consistently two to three times higher in SA women than in WB women. Lowering thresholds to identify GDM, particularly in women of SA origin, identifies more women at risk, but increases costs. Maternal characteristics did not accurately identify women with GDM; there was limited evidence that in some populations risk factors may be useful for identifying low-risk women. Dietary modification additional to routine care reduced the risk of most adverse perinatal outcomes. Metformin (Glucophage,^® Teva UK Ltd, Eastbourne, UK) and insulin were more effective than glibenclamide (Aurobindo Pharma - Milpharm Ltd, South Ruislip, Middlesex, UK). For all strategies to identify and treat GDM, the costs exceeded the health benefits. A policy of no screening/testing or treatment offered the maximum expected net monetary benefit (NMB) of £1184 at a cost-effectiveness threshold of £20,000 per quality-adjusted life-year (QALY). The NMB for the three best-performing strategies in each category (screen only, then treat; screen, test, then treat; and test all, then treat) ranged between -£1197 and -£1210. Further research to reduce uncertainty around potential longer-term benefits for the mothers and offspring, find ways of improving the accuracy of identifying women with GDM, and reduce costs of identification and treatment would be worthwhile.

LIMITATIONS

We did not have access to IPD from populations in the UK outside of England. Few observational studies reported longer-term associations, and treatment trials have generally reported only perinatal outcomes.

CONCLUSIONS

Using the national standard cost-effectiveness threshold of £20,000 per QALY it is not cost-effective to routinely identify pregnant women for treatment of hyperglycaemia. Further research to provide evidence on longer-term outcomes, and more cost-effective ways to detect and treat GDM, would be valuable.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013004608.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Association of maternal exposures with adiposity at age 4/5 years in white British and Pakistani children: findings from the Born in Bradford study

AIMS/HYPOTHESIS

There is evidence that, from birth, South Asians are fatter, for a given body mass, than Europeans. The role of developmental overnutrition related to maternal adiposity and circulating glucose in these ethnic differences is unclear. Our aim was to compare associations of maternal gestational adiposity and glucose with adiposity at age 4/5 years in white British and Pakistani children.

METHODS

Born in Bradford is a prospective study of children born between 2007 and 2010 in Bradford, UK. Mothers completed an OGTT at 27-28 weeks of gestation. We examined associations between maternal gestational BMI, fasting glucose, post-load glucose and diabetes (GDM) and offspring height, weight, BMI and subscapular skinfold (SSF) and triceps skinfold (TSF) thickness at age 4/5 years, using data from 6060 mother-offspring pairs (2717 [44.8%] white British and 3343 [55.2%] Pakistani).

RESULTS

Pakistani mothers had lower BMI and higher fasting and post-load glucose and were twice as likely to have GDM (defined using modified WHO criteria) than white British women (15.8% vs 6.9%). Pakistani children were taller and had lower BMI than white British children; they had similar SSF and lower TSF. Maternal BMI was positively associated with the adiposity of offspring in both ethnic groups, with some evidence of stronger associations in Pakistani mother-offspring pairs. For example, the difference in adjusted mean BMI per 1 kg/m2 greater maternal BMI was 0.07 kg/m2 (95% CI 0.05, 0.08) and 0.10 kg/m2 (95% CI 0.09. 0.11) in white British and Pakistani children, respectively, with equivalent results for SSF being 0.07 mm (95% CI 0.05, 0.08) and 0.09 mm (95% CI 0.08. 0.11) (p for ethnic difference < 0.03 for both). There was no strong evidence of association of fasting and post-load glucose, or GDM, with outcomes in either group.

CONCLUSIONS/INTERPRETATION

At age 4/5 years, Pakistani children are taller and lighter than white British children. While maternal BMI is positively associated with offspring adiposity, gestational glycaemia is not clearly related to offspring adiposity in either ethnic group.

Maternal obesity as a risk factor for early childhood type 1 diabetes: a nationwide, prospective, population-based case-control study

AIMS/HYPOTHESIS

Genetic and environmental factors are believed to cause type 1 diabetes. The aim of this study was to investigate the influence of maternal BMI and gestational weight gain on the subsequent risk of childhood type 1 diabetes.

METHODS

Children in the Swedish National Quality Register for Diabetes in Children were matched with control children from the Swedish Medical Birth Register. Children were included whose mothers had data available on BMI in early pregnancy and gestational weight gain, giving a total of 16,179 individuals: 3231 children with type 1 diabetes and 12,948 control children.

RESULTS

Mothers of children with type 1 diabetes were more likely to be obese (9% [n = 292/3231] vs 7.7% [n = 991/12,948]; p = 0.02) and/or have diabetes themselves (2.8% [n = 90/3231] vs 0.8% [n = 108/12,948]; p < 0.001) compared with mothers of control children. Gestational weight gain did not differ significantly between the two groups of mothers. In mothers without diabetes, maternal obesity was a significant risk factor for type 1 diabetes in the offspring (p = 0.04). A child had an increased risk of developing type 1 diabetes if the mother had been obese in early pregnancy (crude OR 1.20; 95% CI 1.05, 1.38; adjusted OR 1.18; 95% CI 1.02, 1.36). Among children with type 1 diabetes (n = 3231) there was a difference (p < 0.001) in age at onset in relation to the mother's BMI. Among children in the oldest age group (15-19 years), there were more mothers who had been underweight during pregnancy, while in the youngest age group (0-4 years) the pattern was reversed.

CONCLUSIONS/INTERPRETATION

Maternal obesity, in the absence of maternal diabetes, is a risk factor for type 1 diabetes in the offspring, and influences the age of onset of type 1 diabetes. This emphasises the importance of a normal maternal BMI to potentially decrease the incidence of type 1 diabetes.

Maternal and paternal periconceptional nutrition as an indicator of offspring metabolic syndrome risk in later life through epigenetic imprinting: A systematic review

AIMS

This review examined whether maternal and paternal periconceptional nutrition effects an offspring's likelihood of developing chronic metabolic related conditions due to epigenetic imprinting.

METHODS

A literature search was conducted in multiple science databases and limited to studies published after 2012, in English language and peer reviewed. The data from selected articles were extracted and a qualitative approach was employed due to heterogeneity of results.

RESULTS

Newborns from obese fathers showed altered methylation overall and significant hypomethylation at the Insulin-like Growth Factor 2 (IGF2) gene. High maternal pre-pregnancy body mass index (BMI) was associated with altered offspring DNA methylation levels and gestational diabetes mellitus induced significantly increased methylation levels in offspring. Gestational weight gain was not associated with differentially methylated cord blood. Birth weight was higher in offspring exposed to famine in early gestation. Offspring born post maternal bariatric surgery showed a lower percentage of body fat and improved fasting insulin levels compared to siblings born pre-maternal bariatric surgery.

CONCLUSIONS

The available evidence suggests that poor maternal and paternal periconceptional nutrition can increase the risk of metabolic syndrome in offspring, through epigenetic imprinting. Potential parents should be advised that maintaining a healthy diet and BMI is likely to reduce the risk of metabolic syndrome in offspring.

Effect of Gestational Weight Gain and Prepregnancy Body Mass Index in Adolescent Mothers on Weight and Body Mass Index of Adolescent Offspring

PURPOSE

The purpose of the study was to examine the association of the gestational weight gain and prepregnancy body mass index (BMI) of low-income adolescent mothers with the risk of their children being overweight and/or obese in late adolescence.

METHODS

Study subjects were low-income, primiparous adolescents (n = 360) who self-identified as black and participated in the New Mothers Study in Memphis, Tennessee, and their children. Gestational weight gain was examined as a continuous variable and also categorized into overgain, recommended gain, and undergain following the 2009 Institute of Medicine guidelines. The effects of maternal prepregnancy BMI percentiles and calculated BMI were also considered. Multivariable logistic and linear regression models were used. The main outcome measures were offspring overweight, obesity, and BMI.

RESULTS

Thirty-nine percent of offspring were overweight or obese. Higher maternal gestational weight gain increased the risk for offspring overweight and obesity. There was an interaction between gestational weight gain and prepregnancy BMI: offspring of mothers with a BMI percentile ≤76 were at greater risk of obesity with higher maternal weight gain. If mothers with a BMI percentile between the 29th and 83rd percentiles overgained, offspring were at greater risk for overweight. Using calculated BMIs, if a mother's BMI was ≤26 kg/m², offspring risk for obesity was greater with higher gestational weight gain.

CONCLUSIONS

High gestational weight gain had a larger effect on offspring overweight and obesity if maternal prepregnancy BMI percentile was ≤76. The gestational weight gain of primiparous adolescents who self-identified as black had an effect on offspring weight.

Offspring risk of obesity in childhood, adolescence and adulthood in relation to gestational diabetes mellitus: a sex-specific association

Background

Animal data suggest sexually dimorphic programming of obesity in response to altered intrauterine environment, but the longitudinal impact of gestational diabetes mellitus (GDM) on sex-specific risk of offspring obesity in humans is unclear.

Methods

We conducted a prospective analysis of 15 009 US individuals (7946 female and 7063 male) from the Growing-Up Today Study, who were followed from 1996 (ages 9-14 years) through 2010. Height and weight from validated questionnaires were used to derive body mass index (BMI) at different ages. Obesity during childhood (< 18 years) and adulthood (≥ 18 years) were defined using the International Obesity Task Force and the World Health Organization criteria. GDM exposure was identified through self-reported questionnaires from mothers. Relative risks were estimated using multivariable log-binomial regression models with generalized estimating equations accounting for clustering within the same family.

Results

Male offspring born from pregnancies complicated by GDM had higher BMI compared with non-GDM offspring and had increased risk of obesity; the adjusted relative risk [RR, 95% confidence interval (CI)] was 1.47 (1.11-1.95) for all age groups, 1.59 (1.05-2.41) for late childhood, 1.48 (1.06-2.06) for adolescence and 1.39 (1.00-1.94) for early adulthood. No significant association between obesity and maternal GDM was observed among female participants (RR = 0.97, 95% CI: 0.71-1.33).

Conclusions

The association of GDM with offspring obesity from late childhood through early adulthood may differ by sex; a significant association was observed among male but not female offspring.

Early-Life Phthalate Exposure and Adiposity at 8 Years of Age

BACKGROUND

Early-life phthalate exposure may influence child adiposity, but prior studies have not determined if there are periods of enhanced vulnerability to phthalates.

OBJECTIVE

To examine the relationship between child adiposity at 8 y of age and repeated urinary biomarkers of phthalate exposure from gestation through childhood to determine if there are distinct periods of vulnerability.

METHODS

In 219 mother-child pairs from Cincinnati, Ohio, we quantified nine urinary phthalate metabolites up to two times prenatally and six times from 1-8 y of age. We measured child body mass index (BMI), waist circumference, and percent body fat at 8 y of age. To identify periods of vulnerability, we used two statistical methods to estimate phthalate-adiposity associations at each visit, test differences in phthalate-adiposity associations across visits, and model trajectories of phthalate concentrations for children at different levels of adiposity.

RESULTS

Prenatal phthalate concentrations were not associated with excess child adiposity. Monobenzyl phthalate (MBzP) concentrations during pregnancy and childhood were inversely associated with adiposity. The associations of di(2-ethylhexyl) phthalate (∑DEHP) metabolites and monoethyl phthalate (MEP) with child adiposity depended on the timing of exposure. A 10-fold increase in ∑DEHP at 1 and 5 y was associated with a 2.7% decrease [95% confidence interval (CI): -4.8, -0.5] and 2.9% increase (95% CI: 0.3, 5.5) in body fat, respectively. MEP concentrations at 5 and 8 y of age were associated with higher child adiposity, but earlier childhood concentrations were not.

CONCLUSION

In this cohort, we did not find evidence of an obesogenic effect of prenatal phthalate exposure. Positive associations between postnatal MEP and ∑DEHP concentrations depended on the timing of exposure. https://doi.org/10.1289/EHP1022.