Parent-offspring body mass index associations in the Norwegian Mother and Child Cohort Study: a family-based approach to studying the role of the intrauterine environment in childhood adiposity

Understanding risk and causal mechanisms for developing obesity in infants and young children: A National Institutes of Health workshop

Obesity in children remains a major public health problem, with the current prevalence in youth ages 2-19 years estimated to be 19.7%. Despite progress in identifying risk factors, current models do not accurately predict development of obesity in early childhood. There is also substantial individual variability in response to a given intervention that is not well understood. On April 29-30, 2021, the National Institutes of Health convened a virtual workshop on "Understanding Risk and Causal Mechanisms for Developing Obesity in Infants and Young Children." The workshop brought together scientists from diverse disciplines to discuss (1) what is known regarding epidemiology and underlying biological and behavioral mechanisms for rapid weight gain and development of obesity and (2) what new approaches can improve risk prediction and gain novel insights into causes of obesity in early life. Participants identified gaps and opportunities for future research to advance understanding of risk and underlying mechanisms for development of obesity in early life. It was emphasized that future studies will require multi-disciplinary efforts across basic, behavioral, and clinical sciences. An exposome framework is needed to elucidate how behavioral, biological, and environmental risk factors interact. Use of novel statistical methods may provide greater insights into causal mechanisms.

Parental Height and Weight Influence Offspring Adiposity at 2 Years; Findings from the ROLO Kids Birth Cohort Study

OBJECTIVE

 The perinatal period and in utero environment are important for fetal growth, development, and fetal programming. This study aimed to determine the effect of parental anthropometry and the maternal metabolic milieu on offspring adiposity at 2 years of age.

STUDY DESIGN

 This longitudinal birth cohort includes analysis of maternal (n = 337) and paternal (n = 219) anthropometry and maternal and fetal metabolic markers (n = 337), including glucose, homeostatic model of assessment (HOMA), C-peptide, and leptin from participants of the ROLO (the Randomized Control Trial of Low) pregnancy study, and their partners, to determine an association with offspring anthropometry at two years of age.

RESULTS

 Linear regression, when adjusted for confounders, indicated maternal and paternal anthropometry and was associated with offspring weight and length at 2 years of age. Maternal height was negatively associated with general adiposity in the total cohort of children (p = 0.002) and in female children (p = 0.006) and central adiposity in the total child cohort (p < 0.001). Paternal height was also negatively associated with general adiposity in all children (p = 0.002) and central adiposity in total (p = 0.023) and female children (p = 0.008). Maternal glucose, insulin resistance, and fetal C-peptide positively correlated with anthropometry in total, male, and female children.

CONCLUSION

 Parental anthropometry in the perinatal period has a long-lasting effect on offspring anthropometry beyond the neonatal period. Maternal and fetal metabolic factors influence adiposity, and this extends beyond the perinatal period. Parental adiposity may play a significant role in early childhood adiposity and may be a target for interventions to decrease the risk of early childhood obesity.

KEY POINTS

· Parental height and weight were associated with offspring anthropometry and measures of offspring adiposity at 2 years of age.. · Maternal glucose, insulin resistance, and fetal C-peptide correlated with offspring anthropometry.. · Parental anthropometry has long-term effect on offspring adiposity and is seen at 2 years of age..

The role of fathers in child development from preconception to postnatal influences: Opportunities for the National Institutes of Health Environmental influences on Child Health Outcomes (ECHO) program

A growing body of literature highlights the important role of paternal health and socioemotional characteristics in child development, from preconception through adolescence. Much of this research addresses the indirect effects of fathers, for instance, their influence on maternal behaviors during the prenatal period or via the relationship with their partner. However, emerging evidence also recognizes the direct role of paternal health and behavior for child health and adjustment across development. This critical review presents evidence of biological and sociocultural influences of fathers on preconception, prenatal, and postnatal contributions to child development. The National Institutes of Health Environmental influences on Child Health Outcomes (ECHO) program incorporates in its central conceptualization the impact of fathers on family and child outcomes. This critical synthesis of the literature focuses on three specific child outcomes in the ECHO program: health outcomes (e.g., obesity), neurodevelopmental outcomes (e.g., emotional, behavioral, psychopathological development), and positive health. We highlight the unique insights gained from the literature to date and provide next steps for future studies on paternal influences.

Parent-Offspring Associations of Ideal Cardiovascular Health Metrics: Findings From the 2014 to 2021 Korea National Health and Nutrition Examination Survey

BACKGROUND

Studies have reported the strength of cardiovascular health (CVH) metrics in parent-offspring relationships. This study aimed to describe the sex-specific associations between CVH in parents and adult offspring.

METHODS AND RESULTS

This study was conducted on the Korea National Health and Nutrition Examination Survey data set, which analyzed trios of mother-father-child, with the child's age from 20 to 39 years. To use the nature of sampling design, survey weighting was applied to all our analyses. Ideal CVH was defined as a cluster of at least 5 ideal individual CVH metrics. We examined the association between parents and their adult offspring regarding clustering CVH and individual CVH metrics through odds ratios and 95% CIs using multiple logistic regression with standard errors adjusted for within-family clustering. The study included 1267 married couples comprising 748 sons and 819 daughters. After adjusting for household income and offspring's sex, age, education, and alcohol consumption, an offspring with either parent attaining a nonideal CVH was 3.52 times more likely to have nonideal CVH. Fathers' nonideal CVH was significantly positively associated with the daughters' nonideal CVH. Maternal nonideal CVH was significantly positively associated with the son's nonideal CVH. When analyzing individual CVH metrics, ideal status in fathers or mothers reduced the likelihood of their offspring having a nonideal status.

CONCLUSIONS

This cross-sectional study showed positive and differential associations of CVH and its components between parents' and offsprings' nonideal status. Our hypothesis-generating results suggest the relevance of using CVH as a composite indicator in family-centered approaches and heart-health interventions.

Body mass index in parents and their adult offspring: A systematic review and meta-analysis

Obesity may track across generations, due to genetics and shared family environmental factors, or possibly intrauterine programming. However, many studies only assess associations between maternal body mass index (BMI) and offspring BMI in childhood. To determine whether maternal and paternal associations with offspring BMI differ and whether associations persist into adulthood, a systematic review and meta-analysis was done. PubMed, Embase, Web of Science, and Google Scholar (to October 2022) were searched. Observational studies reporting associations between maternal or paternal BMI and adult offspring BMI were included. Offspring BMIs were reported as continuous or categorical measures. Forty-six studies were included in the systematic review. Meta-analyses were conducted using random-effects models. Parental BMI was positively associated with offspring BMI in adulthood. The pooled mother-offspring standardized mean difference (SMD) was 0.23 (95% confidence interval [CI]: 0.20, 0.26), and father-offspring SMD was similar: 0.22 (95% CI: 0.19, 0.25) in adjusted models. Offspring of mothers with overweight or obesity had the same risk of higher BMI as offspring of fathers with overweight or obesity. If these associations are causal, they support interventions targeting all family members, rather than focusing solely on mothers, to obtain a healthy weight development among offspring.

Child and adolescent obesity

The prevalence of child and adolescent obesity has plateaued at high levels in most high-income countries and is increasing in many low-income and middle-income countries. Obesity arises when a mix of genetic and epigenetic factors, behavioural risk patterns and broader environmental and sociocultural influences affect the two body weight regulation systems: energy homeostasis, including leptin and gastrointestinal tract signals, operating predominantly at an unconscious level, and cognitive-emotional control that is regulated by higher brain centres, operating at a conscious level. Health-related quality of life is reduced in those with obesity. Comorbidities of obesity, including type 2 diabetes mellitus, fatty liver disease and depression, are more likely in adolescents and in those with severe obesity. Treatment incorporates a respectful, stigma-free and family-based approach involving multiple components, and addresses dietary, physical activity, sedentary and sleep behaviours. In adolescents in particular, adjunctive therapies can be valuable, such as more intensive dietary therapies, pharmacotherapy and bariatric surgery. Prevention of obesity requires a whole-system approach and joined-up policy initiatives across government departments. Development and implementation of interventions to prevent paediatric obesity in children should focus on interventions that are feasible, effective and likely to reduce gaps in health inequalities.

Comparison of intergenerational instrumental variable analyses of body mass index and mortality in UK Biobank

BACKGROUND

An increasing proportion of people have a body mass index (BMI) classified as overweight or obese and published studies disagree whether this will be beneficial or detrimental to health. We applied and evaluated two intergenerational instrumental variable methods to estimate the average causal effect of BMI on mortality in a cohort with many deaths: the parents of UK Biobank participants.

METHODS

In Cox regression models, parental BMI was instrumented by offspring BMI using an 'offspring as instrument' (OAI) estimation and by offspring BMI-related genetic variants in a 'proxy-genotype Mendelian randomization' (PGMR) estimation.

RESULTS

Complete-case analyses were performed in parents of 233 361 UK Biobank participants with full phenotypic, genotypic and covariate data. The PGMR method suggested that higher BMI increased mortality with hazard ratios per kg/m2 of 1.02 (95% CI: 1.01, 1.04) for mothers and 1.04 (95% CI: 1.02, 1.05) for fathers. The OAI method gave considerably higher estimates, which varied according to the parent-offspring pairing between 1.08 (95% CI: 1.06, 1.10; mother-son) and 1.23 (95% CI: 1.16, 1.29; father-daughter).

CONCLUSION

Both methods supported a causal role of higher BMI increasing mortality, although caution is required regarding the immediate causal interpretation of these exact values. Evidence of instrument invalidity from measured covariates was limited for the OAI method and minimal for the PGMR method. The methods are complementary for interrogating the average putative causal effects because the biases are expected to differ between them.

Paternal preconception modifiable risk factors for adverse pregnancy and offspring outcomes: a review of contemporary evidence from observational studies

BACKGROUND

The preconception period represents transgenerational opportunities to optimize modifiable risk factors associated with both short and long-term adverse health outcomes for women, men, and children. As such, preconception care is recommended to couples during this time to enable them to optimise their health in preparation for pregnancy. Historically, preconception research predominately focuses on maternal modifiable risks and health behaviours associated with pregnancy and offspring outcomes; limited attention has been given to inform paternal preconception health risks and outcomes. This systematic review aims to advance paternal preconception research by synthesising the current evidence on modifiable paternal preconception health behaviours and risk factors to identify associations with pregnancy and/or offspring outcomes.

METHODS

Medline, Embase, Maternity and Infant care, CINAHL, PsycINFO, Scopus, and ISI Proceedings were searched on the 5^th of January 2023, a date limit was set [2012-2023] in each database. A Google Scholar search was also conducted identifying all other relevant papers. Studies were included if they were observational, reporting associations of modifiable risk factors in the preconception period among males (e.g., identified as reproductive partners of pregnant women and/or fathers of offspring for which outcomes were reported) with adverse pregnancy and offspring outcomes. Study quality was assessed using the Newcastle-Ottawa Scale. Exposure and outcome heterogeneity precluded meta-analysis, and results were summarised in tables.

RESULTS

This review identified 56 cohort and nine case control studies. Studies reported on a range of risk factors and/or health behaviours including paternal body composition (n = 25), alcohol intake (n = 6), cannabis use (n = 5), physical activity (n = 2), smoking (n = 20), stress (n = 3) and nutrition (n = 13). Outcomes included fecundability, IVF/ISCI live birth, offspring weight, body composition/BMI, asthma, lung function, leukemia, preterm birth, and behavioural issues. Despite the limited number of studies and substantial heterogeneity in reporting, results of studies assessed as good quality showed that paternal smoking may increase the risk of birth defects and higher paternal BMI was associated with higher offspring birthweight.

CONCLUSION

The current evidence demonstrates a role of paternal preconception health in influencing outcomes related to pregnancy success and offspring health. The evidence is however limited and heterogenous, and further high-quality research is needed to inform clinical preconception care guidelines to support men and couples to prepare for a health pregnancy and child.

Paternal BMI in the preconception period, and the association with child zBMI

BACKGROUND

Rapid growth and excess weight in early childhood are associated with obesity risk. While maternal preconception BMI has been identified as a potential risk factor, the role of paternal preconception BMI is less clear.

OBJECTIVES

To examine the association between paternal preconception BMI and age- and sex-standardized WHO BMI z-score (zBMI) growth rates, zBMI, and weight status, in 0- to 10-year-old children. To determine whether these associations differed by child sex and maternal preconception weight status.

METHODS

A longitudinal cohort study was conducted through The Applied Research Group for Kids (TARGet Kids!). Children (n = 218) underwent repeated measures of height and weight from birth to 10 years old. Piecewise linear mixed models were used to assess the association between paternal preconception BMI and child zBMI growth rates (zBMI SD units/month) between 0, 4, 30, 48 and 120 months of age. Linear mixed models were used to examine the association with child zBMI, and logistic generalized estimation equations (GEE) were used to assess the association with child weight status. Child sex and maternal preconception weight status were tested as effect modifiers.

RESULTS

Paternal preconception BMI was associated with child zBMI growth rate, mean zBMI and weight status in boys, but not girls. A 5 kg/m² higher paternal preconception BMI was associated with approximately 0.01 zBMI SD unit/month higher growth rate for boys born to mothers with preconception overweight. Higher paternal BMI was associated with higher mean zBMI and increased odds of overweight and obesity in boys, with greater effects seen when mothers had preconception overweight compared to normal weight.

CONCLUSION

Paternal preconception BMI was associated with child zBMI growth rate, zBMI and weight status in boys, with greater effects when the biological mother had preconception overweight or obesity. Further understanding of sex differences in paternal preconception weight effects in children is needed.

Glucose and oxygen in the early intrauterine environment and their role in developmental abnormalities

The early life environment can have profound impacts on the developing conceptus in terms of both growth and morphogenesis. These impacts can manifest in a variety of ways, including congenital fetal anomalies, placental dysfunction with subsequent effects on fetal growth, and adverse perinatal outcomes, or via effects on long-term health outcomes that may not be detected until later childhood or adulthood. Two key examples of environmental influences on early development are explored: maternal hyperglycaemia and gestational hypoxia. These are increasingly common pregnancy exposures worldwide, with potentially profound impacts on population health. We explore what is known regarding the mechanisms by which these environmental exposures can impact early intrauterine development and thus result in adverse outcomes in the immediate, short, and long term.

The impact of neonatal parameters and parental factors on body fat level in early childhood

Parental and pregnancy characteristics can affect proportions and tissue composition of the child's bodyand thereforecan influence their present and future health, as well as overall wellbeing. The aim of this study was to examine the differences between selected parental and birth-related parameters among preschool (3-7 years of age) children of varying adiposity status (n=541 girls and n=571 boys).The research was carried out in 20 randomly selected kindergartens in Krakow (Poland). Thickness of 6 skinfolds (biceps, triceps, subscapular, suprailiac, abdominal and calf) was measured. Sum of skinfolds was calculated and participants were divided into low, normal or high body fat groups. Birth-related characteristics were obtained using a questionnaire filled out by the children's parents. Children of mothers who gained the most gestational weight were characterised by high adiposity. Preschoolers with the highest birth weight, body length and head circumference had the greatest adiposity. Children of relatively younger mothers had higher body fat, in comparison to the rest of the study group. Parents of preschoolers in the high adiposity category were characterised by a greater body mass, compared to the parents of children in other body fat groups and that boys with the highest adiposity relatively more often had a close relative with obesity. Children in varying adiposity categories differed in terms of some birth-related factors. Particular attention should be paid to familial and parental characteristics, because they may influence the child's predisposition to excess adiposity deposition later in life.

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.

The role of family factors in the association between early adulthood BMI and risk of cardiovascular disease. An intergenerational study of BMI in early adulthood and cardiovascular mortality in parents, aunts and uncles

Background

High body mass index (BMI) in childhood and adolescence is related to cardiovascular disease (CVD). Causality is not established because common genetic or early life socioeconomic factors (family factors) may explain this relationship. We aimed to study the role of family factors in the association between BMI and CVD by investigating if early adulthood BMI in conscripts and CVD mortality in their parents/aunts/uncles are related.

Methods

Data from the Armed Forces Personnel Database (including height and weight among conscripts) were linked with data from the Norwegian Population Registry, generational data from the Norwegian Family Based Life Course Study, the National Educational Registry and the Cause of Death Registry using unique personal identification numbers. The study sample (N=369 464) was Norwegian males born 1967-1993, who could be linked to both parents and at least one maternal and one paternal aunt or uncle. Subsamples were identified as conscripts whose parents/aunts/uncles had data on cardiovascular risk factors available from Norwegian health surveys. Cox proportional hazards regression models were used to estimate hazard ratios (HR) of CVD mortality in the parental generation according to BMI categories of conscripts.

Results

Parents of conscripts with obesity or overweight had a higher hazard of CVD death (fathers HR obese: 1.99 (1.79,2.21), overweight: 1.33 (1.24,1.42) mothers HR obese: 1.65 (1.32,2.07), overweight: 1.23 (1.07,1.42)) than parents of normal- or underweight conscripts. Aunts and uncles of conscripts with obesity and overweight had an elevated hazard of CVD death, but less so than parents. Adjustment for CVD risk factors attenuated the results in parents, aunts and uncles.

Conclusions

Family factors may impact the relationship between early adulthood overweight and CVD in parents. These can be genes with impact on BMI over generations and genes with a pleiotropic effect on both obesity and CVD, as well as shared environment over generations.

Association between parental and offspring BMI: results from EPACI Portugal 2012

OBJECTIVE

To assess the longitudinal association between parental BMI and offspring's BMI, in EPACI Portugal 2012.

DESIGN

Longitudinal study with retrospective collection of children's anthropometry data since birth. Children's anthropometric data were gathered from individual child health bulletins, and parents' anthropometrics were self-reported. Children's and parents' BMI were classified according to WHO cut-offs. Linear mixed models with random intercept and slope for age were applied to quantify the association between parental BMI and children BMI Z-score (zBMI).

SETTING

EPACI Portugal 2012.

PARTICIPANTS

Representative sample from the Portuguese population (n 2230) aged from 12 to 36 months.

RESULTS

58·9 % of the fathers and 35·6 % of the mothers were overweight (OW) or obese. Prevalence of infants who were, at least, at risk of OW increased from 17·0 % to 30·3 % since birth to 12 months. About half of the mothers with pre-pregnancy OW and obesity (OB) gained gestational weight above the recommendations. The children from mothers with gestational weight gain (GWG) below the recommendations showed a -0·15 SD lower zBMI (95 % CI -0·23, -0·06) in early life, comparing with mothers within GWG recommendations. Children of obese mothers were more likely to present a higher zBMI (0·24 SD, 95 % CI 0·13, 0·35) throughout the first months of life.

CONCLUSIONS

A high prevalence of OW and OB was observed in Portuguese young adults and toddlers. Mothers' pre-pregnancy BMI and insufficient GWG had a direct effect on offspring BMI. Early effective interventions are needed in order to prevent the transgenerational transmission of OB.

Adiposity and cardiovascular outcomes in three-year-old children of participants in UPBEAT, an RCT of a complex intervention in pregnant women with obesity

BACKGROUND

Maternal obesity is associated with offspring cardiometabolic risk. UPBEAT was a randomised controlled trial of an antenatal diet and physical activity intervention in 1555 women with obesity. The intervention was associated with lower gestational weight gain, healthier diet and metabolic profile in pregnancy, and reduced infant adiposity at six months.

OBJECTIVE

We have investigated whether the UPBEAT intervention influenced childhood cardiometabolic outcomes or was associated with sustained improvements in maternal lifestyle 3-years after delivery.

METHODS

In UPBEAT mother-child dyads at the 3-year follow-up, we assessed childhood blood pressure, resting pulse rate, and adiposity (body mass index, skinfold thicknesses, body fat, waist and arm circumferences) and maternal diet, physical activity, and anthropometry.

RESULTS

514 three-year-old children attended the appointment (49% intervention, 51% standard care). There was no difference in the main outcome of interest, subscapular skinfold thickness, between the trial arms (-0.30 mm, 95% confidence interval: -0.92, 0.31). However, the intervention was associated with a lower resting pulse rate (-5 bpm [-8.41, -1.07]). There was also a non-significant lower odds of overweight/obesity (OR 0.73; 0.50, 1.08). Maternal dietary improvements observed in the UPBEAT trial, including glycaemic load and saturated fat were maintained 3-years postpartum.

CONCLUSION

This study has demonstrated that an antenatal dietary and physical activity intervention in women with obesity is associated with lower offspring pulse rate and sustained improvement in maternal diet. Whilst larger than previous cohorts, there remains potential for bias from attrition and these findings require validation in future cohorts.

Do genetic risk scores for childhood adiposity operate independent of BMI of their mothers?

OBJECTIVES

Genetic predisposition and maternal body mass index (BMI) are risk factors for childhood adiposity, defined by either BMI or overweight. We aimed to investigate whether childhood-specific genetic risk scores (GRSs) for adiposity-related traits are associated with childhood adiposity independent of maternal BMI, or whether the associations are modified by maternal BMI.

METHODS

We constructed a weighted 26-SNP child BMI-GRS and a weighted 17-SNP child obesity-GRS in overall 1674 genotyped children within the Danish National Birth Cohort. We applied a case-cohort (N = 1261) and exposure-based cohort (N = 912) sampling design. Using logistic regression models we estimated associations of the GRSs and child overweight at age 7 years and examined if the GRSs influence child adiposity independent of maternal BMI (per standard deviation units).

RESULTS

In the case-cohort design analysis, maternal BMI and the child GRSs were associated with increased odds for childhood overweight [OR for maternal BMI: 2.01 (95% CI: 1.86; 2.17), OR for child BMI-GRS: 1.56 (95% CI: 1.47; 1.66), and OR for child obesity-GRS 1.46 (95% CI: 1.37; 1.54)]. Adjustment for maternal BMI did not change the results, and there were no significant interactions between the GRSs and maternal BMI. However, in the exposure-based cohort design analysis, significant interactions between the child GRSs and maternal BMI on child overweight were observed, suggesting 0.85-0.87-fold attenuation on ORs of child overweight at higher values of maternal BMI and child GRS.

CONCLUSION

GRSs for childhood adiposity are strongly associated with childhood adiposity even when adjusted for maternal BMI, suggesting that the child-specific GRSs and maternal BMI contribute to childhood overweight independent of each other. However, high maternal BMI may attenuate the effects of child GRSs in children.

Epigenetic changes on rat chromosome 4 contribute to disparate alcohol drinking behavior in alcohol-preferring and -nonpreferring rats

BACKGROUND

Paternal alcohol abuse is a well-recognized risk factor for the development of an alcohol use disorder (AUD). In addition to genetic and environmental risk factors, heritable epigenetic factors also have been proposed to play a key role in the development of AUD. However, it is not clear whether epigenetic factors contribute to the genetic inheritance in families affected by AUD. We used reciprocal crosses of the alcohol-preferring (P) and -nonpreferring (NP) rat lines to test whether epigenetic factors also impacted alcohol drinking in up to two generations of offspring.

METHODS

F1 offspring derived by reciprocal breeding of P and NP rats were tested for differences in alcohol consumption using a free-choice protocol of 10% ethanol, 20% ethanol, and water that were available concurrently. In a separate experiment, an F2 population was tested for alcohol consumption not only due to genetic differences. These rats were generated from inbred P (iP) and iNP rat lines that were reciprocally bred to produce genetically identical F1 offspring that remained alcohol-naïve. Intercrosses of the F1 generation animals produced the F2 generation. Alcohol consumption was then assessed in the F2 generation using a standard two-bottle choice protocol, and was analyzed using genome-wide linkage analysis. Alcohol consumption measures were also analyzed for sex differences.

RESULTS

Average alcohol consumption was higher in the F1 offspring of P vs. NP sires and in the F2 offspring of F0 iP vs. iNP grandsires. Linkage analyses showed the maximum LOD scores for alcohol consumption in both male and female offspring were on chromosome 4 (Chr 4). The LOD score for both sexes considered together was higher when the grandsire was iP vs. iNP (5.0 vs. 3.35, respectively). Furthermore, the F2 population displayed enhanced alcohol consumption when the P alleles from the F0 sire were present.

CONCLUSIONS

These results demonstrate that epigenetic and/or non-genetic factors mapping to rat chromosome 4 contribute to a transgenerational paternal effect on alcohol consumption in the P and NP rat model of AUD.

Maternal and gestational influences on childhood blood pressure

Exposures that contribute to a sub-optimal intrauterine environment can have an effect on the developing fetus. Impaired fetal growth that results in low birth weight is an established risk factor for cardio-metabolic disorders later in life. Recent epidemiologic and prospective cohort studies that include the maternal and gestational period have identified maternal and gestational conditions that confer increased risk for subsequent cardio-metabolic disorders in the absence of low birth weight. Maternal pre-conception health status, including chronic obesity and type 2 diabetes, increase risk for childhood obesity and obesity-related higher blood pressure (BP) in child offspring. Maternal gestational exposures, including gestational diabetes, gestational hypertension, and preeclampsia, are associated with higher BP in offspring. Other maternal exposures such as cigarette smoke and air pollution also increase risk for higher BP in child offspring. Recent, but limited, data indicate that assisted reproductive technologies can be associated with hypertension in childhood, despite otherwise normal gestation and healthy newborn. Gestational exposures associated with higher BP in childhood can be related to familial lifestyle factors, genetics, or epigenetic modification of fetal deoxyribonucleic acid (DNA). These factors, or combination of factors, as well as other adverse intrauterine conditions, could induce fetal programing leading to health consequences in later life. Current and developing research will provide additional insights on gestational exposures and fetal adjustments that increase risk for higher BP levels in childhood.

The influence of transmitted and non-transmitted parental BMI-associated alleles on the risk of overweight in childhood

Overweight in children is strongly associated with parental body mass index (BMI) and overweight. We assessed parental transmitted and non-transmitted genetic contributions to overweight in children from the Danish National Birth Cohort by constructing genetic risk scores (GRSs) from 941 common genetic variants associated with adult BMI and estimating associations of transmitted maternal/paternal and non-transmitted maternal GRS with child overweight. Maternal and paternal BMI (standard deviation (SD) units) had a strong association with childhood overweight [Odds ratio (OR): 2.01 (95% confidence interval (CI) 1.74; 2.34) and 1.64 (95% CI 1.43; 1.89)]. Maternal and paternal transmitted GRSs (SD-units) increased odds for child overweight equally [OR: 1.30 (95% CI 1.16; 1.46) and 1.30 (95% CI 1.16; 1.47)]. However, both the parental phenotypic and the GRS associations may depend on maternal BMI, being weaker among mothers with overweight. Maternal non-transmitted GRS was not associated with child overweight [OR 0.98 (95% CI 0.88; 1.10)] suggesting no specific influence of maternal adiposity as such. In conclusion, parental transmitted GRSs, based on adult BMI, contribute to child overweight, but in overweight mothers other genetic and environmental factors may play a greater role.

Exploring the role of genetic confounding in the association between maternal and offspring body mass index: evidence from three birth cohorts

BACKGROUND

Maternal pre-pregnancy body mass index (BMI) is positively associated with offspring birth weight (BW) and BMI in childhood and adulthood. Each of these associations could be due to causal intrauterine effects, or confounding (genetic or environmental), or some combination of these. Here we estimate the extent to which the association between maternal BMI and offspring body size is explained by offspring genotype, as a first step towards establishing the importance of genetic confounding.

METHODS

We examined the associations of maternal pre-pregnancy BMI with offspring BW and BMI at 1, 5, 10 and 15 years, in three European birth cohorts (n ≤11 498). Bivariate Genomic-relatedness-based Restricted Maximum Likelihood implemented in the GCTA software (GCTA-GREML) was used to estimate the extent to which phenotypic covariance was explained by offspring genotype as captured by common imputed single nucleotide polymorphisms (SNPs). We merged individual participant data from all cohorts, enabling calculation of pooled estimates.

RESULTS

Phenotypic covariance (equivalent here to Pearson's correlation coefficient) between maternal BMI and offspring phenotype was 0.15 [95% confidence interval (CI): 0.13, 0.17] for offspring BW, increasing to 0.29 (95% CI: 0.26, 0.31) for offspring 15 year BMI. Covariance explained by offspring genotype was negligible for BW [-0.04 (95% CI: -0.09, 0.01)], but increased to 0.12 (95% CI: 0.04, 0.21) at 15 years, which is equivalent to 43% (95% CI: 15%, 72%) of the phenotypic covariance. Sensitivity analyses using weight, BMI and ponderal index as the offspring phenotype at all ages showed similar results.

CONCLUSIONS

Offspring genotype explains a substantial fraction of the covariance between maternal BMI and offspring adolescent BMI. This is consistent with a potentially important role for genetic confounding as a driver of the maternal BMI-offspring BMI association.

Influence of post-partum BMI change on childhood obesity and energy intake

Introduction

Association between parent’s Body Mass Index (BMI) and their children, has been widely documented. Individual, familiar and structural factors play a role in this relation. We analyzed the association between maternal BMI change during the first year post-partum and their offspring’s growth-trajectories and energy intake in their first five years of life.

Objective

Compare growth-trajectories and children’s caloric intake according to post-partum mother´s BMI classification.

Methods

The anthropometric assessment was taken in 935 mother-child pairs along the study period. Mothers were classified into four groups according to their BMI-trajectories in the post-partum. Children’s weight for height z-scores (WHZ) was compared among groups using random-effects regression models. A longitudinal comparison of children’s caloric intake by the maternal group was carried out.

Results

At 42 months of age, infants from mothers that remained overweight during the first year post-partum had, on average, 0.61 SD higher WHZ than those from mothers who remained in a recommended BMI group (R-BMI) in the same period. At 60 months of age, children´s prevalence of obesity was almost twice in the maternal overweight group vs R-BMI group (14.2% and 7.3% respectively). Chances for a child of having an over caloric intake were 36.5% (95% IC: 6.6%, 74.8%) and significantly higher among children from overweight mothers than those from R-BMI mothers. The difference in children’s WHZ trajectory remained significant after adjusting for caloric intake, suggesting that contextual factors play a role in shaping children’s obesity. A concurrent ethnographic study with the study subjects provides suggestions as to what these factors might be, including changes in the food landscape.

Conclusion

Children from overweight mothers tended to have a more caloric diet yielding a higher propensity to obesity. Contextual factors such as food landscape might contribute to childhood obesity beyond having an overweight mother. Pregnancy and post-partum is a window of opportunity for interventions to decrease the incidence of children’s overweight.

Change in Children's Self-Concept, Body-Esteem, and Eating Attitudes Before and 4 Years After Maternal RYGB

Introduction

The aim of the present study was to look at longitudinal changes in children’s self-concept, body-esteem, and eating attitudes before and 4 years after maternal RYGB surgery.

Methods

Sixty-nine women and 81 appurtenant children were recruited from RYGB waiting lists at 5 hospitals in Sweden. Families were visited at home pre-surgery, 9 months, and 4 years post-maternal RYGB to measure BMI. Furthermore, all participating family members completed questionnaires. Mothers’ questionnaires measured eating behavior, depression, anxiety, and sleep quality, and children’s questionnaires measured body-esteem, self-concept, and eating attitudes.

Results

Thirty-five/sixty-nine mothers and 43/81 children participated in all 3 measurements. Mothers reduced their BMI from pre-surgery (39.2) to 9 months (27.0) and 4 years post-surgery (27.4). Children’s prevalence of overweight/obesity was lower 9 months post-surgery (48.8%) but at the same levels again 4 years post-surgery (58.1%), compared to pre-surgery (58.1%). The same rebound pattern was seen among children’s eating attitudes, mothers’ symptoms of depression and anxiety, and sleep quality. We found no correlations between mothers’ BMI or eating behavior and children’s BMI or eating behavior.

Conclusion

Children’s prevalence of overweight/obesity and eating attitudes improves soon after their mothers’ RYGB, but then return to pre-surgery levels at 4 years post-surgery, as do mothers’ sleep quality and symptoms of depression and anxiety, even though their weight loss was maintained.

Electronic supplementary material

The online version of this article (10.1007/s11695-018-3348-z) contains supplementary material, which is available to authorized users.

The effect of maternal and paternal height and weight on antenatal, perinatal and postnatal morphology in sex-stratified analyses

INTRODUCTION

Low birthweight is associated with diseases later in life. The mechanisms for these associations are not well known. If the hypothesis concerning "maternal constraint" is correct for humans, as shown in animal experiments, we expect the maternal, not paternal, body proportions to influence antenatal growth and those of both parents to influence postnatal growth. We aimed to study the effect of maternal and paternal height and weight on fetal femur length antenatally (gestational weeks 20 and 30) and body length and weight at birth and postnatally (12 and 24 months old) in both sexes.

MATERIAL AND METHODS

In this prospective cohort study, 399 healthy pregnant women aged 20-42 years were recruited at The Mercy Hospital for Woman, Melbourne, Australia from 2008 to 2009. Fetal femur length was measured using antenatal ultrasound (gestational weeks 20 and 30). Body length and weight were measured for parents and offspring at birth and postnatally (12 and 24 months).

RESULTS

Each standard deviation (SD) rise in maternal weight (15.5 kg) was associated with 0.24 SD (0.5 mm) and 0.18 SD (0.4 mm) longer femur length in female and male fetuses at week 20 and 0.17 SD (0.5 mm) and 0.38 SD (1.1 mm) longer femur length in female and male fetuses at week 30, respectively. In girls, each SD rise in paternal height (7.2 cm) was associated with 0.29 SD (0.6 cm) longer birth length. In boys, each SD rise in maternal height (6.7 cm) was associated with 0.23 SD (0.5 cm) longer birth length. In both sexes, parental height and weight were associated with offspring length and weight at 12 and 24 months (SD ranging from 0.20 to 0.38, length from 0.7 to 1.5 cm and weight from 0.3 to 0.6 kg). The multivariable linear regression analyses were adjusted for parental age, height and weight, maternal smoking, alcohol intake, parity, and ethnicity, all P < 0.05.

CONCLUSIONS

Maternal, not paternal, body proportions determined fetal growth in both sexes. Paternal height predicted birth length in girls. In contrast, maternal height predicted birth length in boys. Both parents predicted postnatal body proportions at 12 and 24 months in both sexes.

From conception to infancy - early risk factors for childhood obesity

Maternal lifestyle during pregnancy, as well as early nutrition and the environment infants are raised in, are considered relevant factors for the prevention of childhood obesity. Several models are available for the prediction of childhood overweight and obesity, yet most have not been externally validated. Moreover, the factors considered in the models differ among studies as the outcomes manifest after birth and depend on maturation processes that vary between individuals. The current Review examines and interprets data on the early determinants of childhood obesity to provide relevant strategies for daily clinical work. We evaluate a selection of prenatal and postnatal factors associated with child adiposity. Actions to be considered for preventing childhood obesity include the promotion of healthy maternal nutrition and weight status at reproductive age and during pregnancy, as well as careful monitoring of infant growth to detect early excessive weight gain. Paediatricians and other health-care professionals should provide scientifically validated, individual nutritional advice to families to counteract excessive adiposity in children. Based on systematic reviews, original papers and scientific reports, we provide information to help with setting up public health strategies to prevent overweight and obesity in childhood.

Breastfeeding duration is associated with offspring’s adherence to prudent dietary pattern in adulthood: results from the Nutritionist’s Health Study

Little is known about the long-term effect of breastfeeding on dietary habits. We examined the association between breastfeeding duration and adherence to current dietary patterns of young women. This was a cross-sectional analysis of 587 healthy women aged ≤45 years, undergraduates or nutrition graduates. Maternal characteristics and breastfeeding duration [<6; 6–<12; ≥12 months (reference)] were recalled. Diet was assessed using a food frequency questionnaire and patterns were identified using factor analysis by principal component. Adherence to patterns was categorized in tertiles; the first (T1 = reference) was compared to T2 + T3 (moderate-to-high adherence). Logistic regression was performed considering the minimal sufficient adjustment recommended by the directed acyclic graph. Median age was 22 (interquartile range (IQR) 20; 27) years and body mass index (BMI) 22.2 (IQR 20.4; 25.0) kg/m2. The four dietary patterns identified (Processed, Prudent, Brazilian and Lacto-vegetarian) explained 27% of diet variance. Women breastfed for <6 months showed lower chance of moderate-to-high adherence to the Prudent pattern (odds ratio (OR) = 0.53, p = 0.04). Breastfeeding was not associated with the other patterns. Maternal pre-pregnancy BMI was directly associated with moderate-to-high adherence to the Processed pattern (OR = 2.01, p = 0.03) and inversely to the Prudent pattern (OR = 0.52, p = 0.02). Higher adherence to the Brazilian pattern was associated with proxies of low socioeconomic status and the Lacto-vegetarian pattern with the opposite. Confirmation in prospective studies of the association found in this study between breastfeeding with the Prudent pattern in adult offspring could suggest that early feeding practices influence long-term dietary habits, which could then affect the risk of nutrition-related diseases.

The association between maternal body mass index and child obesity: A systematic review and meta-analysis

BACKGROUND

There is a global obesity crisis, particularly among women and disadvantaged populations. Early-life intervention to prevent childhood obesity is a priority for public health, global health, and clinical practice. Understanding the association between childhood obesity and maternal pre-pregnancy weight status would inform policy and practice by allowing one to estimate the potential for offspring health gain through channelling resources into intervention. This systematic review and meta-analysis aimed to examine the dose-response association between maternal body mass index (BMI) and childhood obesity in the offspring.

METHODS AND FINDINGS

Searches in MEDLINE, Child Development & Adolescent Studies, CINAHL, Embase, and PsycInfo were carried out in August 2017 and updated in March 2019. Supplementary searches included hand-searching reference lists, performing citation searching, and contacting authors. Two researchers carried out independent screening, data extraction, and quality assessment. Observational studies published in English and reporting associations between continuous and/or categorical maternal and child BMI or z-score were included. Categorical outcomes were child obesity (≥95th percentile, primary outcome), overweight/obesity (≥85th percentile), and overweight (85th to 95th percentile). Linear and nonlinear dose-response meta-analyses were conducted using random effects models. Studies that could not be included in meta-analyses were summarised narratively. Seventy-nine of 41,301 studies identified met the inclusion criteria (n = 59 cohorts). Meta-analyses of child obesity included 20 studies (n = 88,872); child overweight/obesity, 22 studies (n = 181,800); and overweight, 10 studies (n = 53,238). Associations were nonlinear and there were significantly increased odds of child obesity with maternal obesity (odds ratio [OR] 3.64, 95% CI 2.68-4.95) and maternal overweight (OR 1.89, 95% CI 1.62-2.19). Significantly increased odds were observed for child overweight/obesity (OR 2.69, 95% CI 2.10-3.46) and for child overweight (OR 1.80, 95% CI 1.25, 2.59) with maternal obesity. A limitation of this research is that the included studies did not always report the data in a format that enabled inclusion in this complex meta-analysis.

CONCLUSIONS

This research has identified a 264% increase in the odds of child obesity when mothers have obesity before conception. This study provides substantial evidence for the need to develop interventions that commence prior to conception, to support women of childbearing age with weight management in order to halt intergenerational obesity.

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 role of offspring’s birthweight on the association between pre-pregnancy obesity and offspring’s childhood anthropometrics: a mediation analysis

While birthweight of offspring is associated with pre-pregnancy body mass index (BMI) and later risk of obesity, its mediating effect between the association of maternal pre-pregnancy BMI and offspring’s childhood anthropometrics has rarely been investigated. This study aimed to examine whether offspring birthweight is a mediator in the association between pre-pregnancy BMI and offspring’s childhood anthropometrics. The study included 1,618 mother–child pairs from the Australian Longitudinal Study on Women’s Health and Mothers and their Children’s Health Study. Children’s anthropometrics [mean age 8.6 (s.d. =3.0) years] were calculated from the mothers’ self-reported child weight and height measures. G-computation was used to estimate the natural direct and indirect (via birthweight) effects of pre-pregnancy BMI. In the fully adjusted model for maternal sociodemographic and lifestyle factors, the natural direct effects of pre-pregnancy obesity on child BMI-for-age, height-for-age, weight-for-age and weight-for-height outcomes were, β (95% confidence interval, CI), 0.75 (0.55, 0.95), 0.13 (−0.07, 0.32), 0.62 (0.44, 0.80) and 0.57 (0.24, 0.90), respectively. The corresponding natural indirect effects were 0.04 (−0.04, 0.12), −0.01 (−0.09, 0.07), −0.01 (−0.08, 0.07) and 0.09 (−0.05, 0.23). Similar results were observed for pre-pregnancy overweight and pre-pregnancy BMI as a continuous scale. Most of the effect of pre-pregnancy obesity on childhood weight-related anthropometric outcomes appears to be via a direct effect, not mediated through offspring’s birthweight.

Association of Maternal Prepregnancy Weight with Offspring Adiposity Throughout Adulthood over 37 Years of Follow-up

OBJECTIVE

This study aimed to determine the relation of maternal prepregnancy weight with offspring BMI across adulthood from almost 40 years of follow-up.

METHODS

BMI was measured in Framingham Heart Study Offspring cohort participants between 1971 and 2008. The association of maternal prepregnancy weight category (ascertained via direct measure and questionnaire) with serial offspring BMI, overweight, obesity, and change in BMI over time was tested, adjusted for age, sex, and a BMI genetic risk score; secondary models additionally adjusted for physical activity, dietary factors, smoking, education, and familial relatedness.

RESULTS

Among 863 participants at initial assessment (83 exposed and 780 controls), mean (SD) age was 33 (10) years, 53% were female, and mean BMI was 24.5 (4.1) kg/m² . Exposed offspring BMI was higher at every examination cycle, ranging from 1.5 (0.5) to 3.0 (0.5) kg/m² (P < 0.001), with larger differences at later assessments. The rate of increase in offspring BMI over time was higher in exposed offspring before the age of 50 years (β [SE] = 0.07 [0.02] kg/m² per year; P = 0.004) but not after the age of 50 years (-0.05 [0.04] kg/m² per year; P = 0.2).

CONCLUSIONS

Maternal prepregnancy weight is associated with greater offspring BMI throughout adulthood, with more rapid weight acceleration in early and midadulthood.

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.

Impact of parental weight status on children's body mass index in early life: evidence from a Chinese cohort

OBJECTIVES

To understand whether parents' weight status before conception predicts body mass index (BMI) of their offspring in early life and the differences between the mother-child and father-child associations.

DESIGN

A birth cohort study.

SETTING

Conducted at the Community Health Service Centre in Shenyang, Wuhan and Guangzhou.

PARTICIPANTS

A total of 2220 live birth newborns were recruited randomly after consent of their parents, and 1178 were followed up until 2 years old.

METHODS

Parental demographics, maternal characteristics during pregnancy, children's anthropometric data and feeding patterns at 1 month old were collected. BMI was calculated and BMI Z-scores (BMI_Z) were generated by referring to WHO growth standard. Parental weight status was categorised into underweight, normal weight, and overweight and obese according to the Working Group of Obesity in China. General linear models and generalised linear models were used to assess the associations between parents and offspring.

OUTCOME MEASURES

The primary outcomes were descriptive data on child's sex-specific anthropometric variables. The secondary outcomes were BMI_Z and weight status of children at each time point.

RESULTS

No gender difference was observed in BMI_Z or overweight or obesity rates from birth to 24 months old, although boys were significantly heavier and had a greater length/height than girls (P<0.05). The overweight and obesity rates of children peaked at 12 months old. Maternal BMI/weight status had a significant but small effect on BMI_Z at birth, but not on the paternal side. The impact of parental BMI on child's BMI_Z after birth was similar at each follow-up. Offspring with underweight mothers tend to have reduced BMI_Z after birth while overweight/obese fathers had children with a greater BMI_Z.

CONCLUSIONS

Maternal weight status had small effect on both fetal and child growth after birth. Significant but mild paternal influence was only detected after birth.

A Mathematical Model for Predicting Obesity Transmission with Both Genetic and Nongenetic Heredity

OBJECTIVE

Obesity is transmissible across generations through both genetic and nongenetic routes, but distinguishing between these factors is challenging. This study aimed to quantitatively examine the contribution of these genetic and nongenetic effects to assess their influence on obesity prevalence.

METHODS

A mathematical model was proposed that incorporated both the genetic and nongenetic effects of obesity. Model parameters were estimated by using observational data. Model simulations were used to assess the sensitivity of model parameters. To strengthen the study's approach, parameter estimation and simulation using data from the United Kingdom were also performed.

RESULTS

Individuals homozygous for a "hypothetical obesogenic gene" were suggested to be more susceptible to both socially contagious risk and spontaneous weight gain risk. The model predicted that obesity prevalence would reach 41.03% (39.28, 44.31) and 26.77% (25.62, 28.06) at 2030 in the United States and United Kingdom, respectively. The socially contagious risk factor had a greater overall impact on the distribution of the population with obesity than did spontaneous weight gain risk or mother-to-child obesity transmission risk.

CONCLUSIONS

Although the proposed "first approximation" model captured the complex interactions between the genetic and nongenetic effects on obesity, this framework remains incomplete. Future work should incorporate other key features driving the obesity epidemic.

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.

Chemical and non-chemical stressors affecting childhood obesity: a systematic scoping review

Childhood obesity in the United States has doubled over the last three decades and currently affects 17% of children and adolescents. While much research has focused on individual behaviors impacting obesity, little research has emphasized the complex interactions of numerous chemical and non-chemical stressors found in a child's environment and how these interactions affect a child's health and well-being. The objectives of this systematic scoping review were to (1) identify potential chemical stressors in the context of non-chemical stressors that impact childhood obesity; and, (2) summarize our observations for chemical and non-chemical stressors in regards to child-specific environments within a community setting. A review was conducted to identify chemical and non-chemical stressors related to childhood obesity for the childhood life stages ranging from prenatal to adolescence. Stressors were identified and grouped into domains: individual behaviors, family/household behaviors, community stressors, and chemical exposures. Stressors were related to the child and the child's everyday environments and used to characterize child health and well-being. This review suggests that the interactions of chemical and non-chemical stressors are important for understanding a child's overall health and well-being. By considering these relationships, the exposure science research community can better design and implement strategies to reduce childhood obesity.

Confounding by ill health in the observed association between BMI and mortality: evidence from the HUNT Study using offspring BMI as an instrument

Background

The observational association between mortality and body mass index (BMI) is U-shaped, leading to highly publicized suggestions that moderate overweight is beneficial to health. However, it is unclear whether elevated mortality is caused by low BMI or if the association is confounded, for example by concurrent ill health.

Methods

Using HUNT, a Norwegian prospective study, 32 452 mother-offspring and 27 747 father-offspring pairs were followed up to 2009. Conventional hazard ratios for parental mortality per standard deviation of BMI were estimated using Cox regression adjusted for behavioural and socioeconomic factors. To estimate hazard ratios with reduced susceptibility to confounding, particularly from concurrent ill health, the BMI of parents’ offspring was used as an instrumental variable for parents’ own BMI. The shape of mortality-BMI associations was assessed using cubic splines.

Results

There were 18 365 parental deaths during follow-up. Conventional associations of mortality from all-causes, cardiovascular disease and cancer with parents’ own BMI were substantially nonlinear, with elevated mortality at both extremes and minima at 21–25 kg m⁻². Equivalent associations with offspring BMI were positive and there was no evidence of elevated parental mortality at low offspring BMI. The linear instrumental variable hazard ratio for all-cause mortality per standard deviation increase in BMI was 1.18 (95% confidence interval: 1.10, 1.26), compared with 1.05 (1.03, 1.06) in the conventional analysis.

Conclusions

Elevated mortality rates at high BMI appear causal, whereas excess mortality at low BMI is likely exaggerated by confounding by factors including concurrent ill health. Conventional studies probably underestimate the adverse population health consequences of overweight.

Association between gestational diabetes mellitus exposure and childhood adiposity is not substantially explained by offspring genetic risk of obesity

AIM

To examine the extent to which offspring obesity-associated genetic risk explains the association between gestational diabetes mellitus and childhood adiposity.

METHODS

We studied 282 children aged 7-12 years who were enrolled in the Exploring Perinatal Outcomes in Children Study. A genetic risk score for BMI was calculated as the count of 91 established BMI-raising risk alleles. Multivariable linear and logistic regression models were used to estimate associations between the offspring genetic risk score and exposure to gestational diabetes and childhood adiposity (BMI and waist circumference), adjusting for clinical and demographic covariates. The contribution of offspring genetic risk to associations between maternal gestational diabetes and childhood outcomes was estimated by comparing the regression coefficients for the gestational diabetes variable in models with and without the genetic risk score.

RESULTS

The offspring BMI genetic risk score was associated with childhood BMI (P = 0.006) and waist circumference (P = 0.02), and marginally with gestational diabetes (P = 0.05). Offspring BMI genetic risk did not contribute significantly to associations between gestational diabetes and childhood BMI [7.7% (95% CI -3.3, 18.8)] or waist circumference [5.8% (95% CI -3.1, 14.8); P = 0.2 for both].

CONCLUSIONS

Offspring obesity genetic risk does not explain a significant proportion of the association between gestational diabetes exposure and childhood adiposity. The association between gestational diabetes and childhood adiposity is probably explained through alternative pathways, including direct intrauterine effects or a shared postnatal environment.

Maternal BMI at the start of pregnancy and offspring epigenome-wide DNA methylation: findings from the pregnancy and childhood epigenetics (PACE) consortium

Pre-pregnancy maternal obesity is associated with adverse offspring outcomes at birth and later in life. Individual studies have shown that epigenetic modifications such as DNA methylation could contribute. Within the Pregnancy and Childhood Epigenetics (PACE) Consortium, we meta-analysed the association between pre-pregnancy maternal BMI and methylation at over 450,000 sites in newborn blood DNA, across 19 cohorts (9,340 mother-newborn pairs). We attempted to infer causality by comparing the effects of maternal versus paternal BMI and incorporating genetic variation. In four additional cohorts (1,817 mother-child pairs), we meta-analysed the association between maternal BMI at the start of pregnancy and blood methylation in adolescents. In newborns, maternal BMI was associated with small (<0.2% per BMI unit (1 kg/m2), P < 1.06 × 10-7) methylation variation at 9,044 sites throughout the genome. Adjustment for estimated cell proportions greatly attenuated the number of significant CpGs to 104, including 86 sites common to the unadjusted model. At 72/86 sites, the direction of the association was the same in newborns and adolescents, suggesting persistence of signals. However, we found evidence for acausal intrauterine effect of maternal BMI on newborn methylation at just 8/86 sites. In conclusion, this well-powered analysis identified robust associations between maternal adiposity and variations in newborn blood DNA methylation, but these small effects may be better explained by genetic or lifestyle factors than a causal intrauterine mechanism. This highlights the need for large-scale collaborative approaches and the application of causal inference techniques in epigenetic epidemiology.

Paternal programming of offspring cardiometabolic diseases in later life

Early - intrauterine - environmental factors are linked to the development of cardiovascular disease in later life. Traditionally, these factors are considered to be maternal factors such as maternal under and overnutrition, exposure to toxins, lack of micronutrients, and stress during pregnancy. However, in the recent years, it became obvious that also paternal environmental factors before conception and during sperm development determine the health of the offspring in later life. We will first describe clinical observational studies providing evidence for paternal programming of adulthood diseases in progeny. Next, we describe key animal studies proving this relationship, followed by a detailed analysis of our current understanding of the underlying molecular mechanisms of paternal programming. Alterations of noncoding sperm micro-RNAs, histone acetylation, and targeted as well as global DNA methylation seem to be in particular involved in paternal programming of offspring's diseases in later life.

Parental pre-pregnancy obesity and the risk of offspring weight and body mass index change from childhood to adulthood

The purpose of this study was to examine the association of parental pre-pregnancy weight and body mass index (BMI) on offspring weight and BMI change from childhood to adulthood. We analysed BMI data from a subsample of parents (n = 1494) from the Mater-University of Queensland Study of Pregnancy cohort that started in the early 1980s in Brisbane, Australia: data were collected at pre-pregnancy and then also for offspring at 5, 14 and 21-year follow-ups. Multiple regression for continuous outcomes and multinomial regression for categorical outcomes were performed. A total of 14.7% of offspring experienced BMI change from normal at 5 years to overweight or obese (OW/OB) at 14 years, 15.3% of normal at 14 years to OW/OB at 21 years and 22.8% from normal at 5 years to OW/OB at 21 years. Overall, the strength of the association of parental BMI with offspring BMI was stronger as offspring become older. Pre-pregnancy parental BMI differentially impacts offspring OW/OB across the life course. For every unit increase in paternal and maternal BMI z-score, offspring BMI z-score increased, on average, by between 0.15% (kg m^-2 ) and 0.24% (kg m^-2 ) throughout all three stages of life when both parents were OW/OB; these associations were stronger than with one parent. Parental pre-pregnancy BMI and OW/OB is a strong predictor of offspring weight and BMI change from early life to adulthood.

Associations of maternal obesity and excessive weight gain during pregnancy with subcutaneous fat mass in infancy

BACKGROUND

Not much is known about the associations of maternal obesity and excessive gestational weight gain with body fat in infancy.

OBJECTIVE

To examine the associations of maternal pre-pregnancy body mass index and gestational weight gain with infant subcutaneous fat.

METHODS

In a population-based prospective cohort study among 845 mothers and their infants, we obtained maternal pre-pregnancy body mass index and measured maternal weight during pregnancy. At 1.5, 6 and 24months, we estimated infant total subcutaneous fat (sum of biceps, triceps, suprailiacal and subscapular skinfold thicknesses) and central-to-total subcutaneous fat ratio (sum of suprailiacal and subscapular skinfold thicknesses/total subcutaneous fat).

RESULTS

Maternal body mass index was positively associated with higher infant body mass index from 6months onwards. Maternal body mass index was not associated with infant subcutaneous fat measures at 1.5 or 6months. A 1-standard deviation scores (SDS) higher maternal body mass index was associated with a 0.09 (95% Confidence Interval 0.01, 0.17) SDS higher infant total subcutaneous fat at 24months, but not with central-to-total subcutaneous fat ratio. No associations were present for maternal total or period-specific gestational weight gain with infant fat.

CONCLUSION

Maternal body mass index was positively associated with infant body mass index and total subcutaneous fat in late infancy. Maternal total and period-specific gestational weight gain were not associated with infant body fat mass measures.

Maternal and Early Childhood Determinants of Women's Body Size in Midlife: Overall Cohort and Sibling Analyses

Observational evidence suggests that adult body size has its roots earlier in life, yet few life-course studies have data on siblings with which to control for family-level confounding. Using prospective data from the Early Determinants of Mammographic Density Study (n = 1,108; 1959-2008), we examined the association of maternal prepregnancy body mass index (BMI; weight (kg)/height (m)2), gestational weight gain (GWG), birth size, and childhood growth factors with adult BMI in daughters at midlife using quantile, linear, and logistic regression models. We compared overall cohort findings (n = 1,108) with sibling differences (n = 246 sibling sets). Results derived by all 3 regression methods supported positive and independent associations of prepregnancy BMI, GWG, and percentile change in early childhood growth with BMI in daughters at midlife. Sibling analyses demonstrated that higher GWG was independently related to a higher adult BMI in daughters, particularly for the highest 90th quantile of adult BMI (β = 0.64 (standard error, 0.26) BMI units). Greater increases in weight percentiles between 1 and 4 years of age within siblings were also associated with higher adult BMI in the 75th quantile (β = 0.06 (standard error, 0.03) kg). Thus, even after consideration of the role of family-level fixed effects, maternal GWG and childhood weight gain are associated with adult body size in midlife.

Increased Cortisol and Cortisone Levels in Overweight Children

BACKGROUND It has been unclear whether relatively high cortisol and cortisone levels are related to overweight in childhood, parental body mass index (BMI), and family dietary habits. The aim of this study was to compare cortisol and cortisone levels in urine and saliva from overweight and normal children, as well as correlations between children's BMI, parental BMI and family dietary behavior questionnaire score (QS). MATERIAL AND METHODS We analyzed the data from 52 overweight children and 53 age- and sex-matched normal-weight children aged 4-5 years. The concentrations of salivary cortisol (SF), salivary cortisone (SE), urinary cortisol (UF) and urinary cortisone (UE) were measured using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The family dietary behavior QS was answered by the parent mainly responsible for the family diet. RESULTS Average cortisol and cortisone levels were significantly higher in overweight children. There was no significant difference in the ratio of cortisol to cortisone (Rcc) and the marker of 11b-hydroxysteroid dehydrogenase type 2 (11β-HSD2) activities. The results displayed correlations among cortisol, cortisone, and Rcc. Positive correlations were weak-to-moderate between BMI and SF, SE, UF, and UE. There were correlations between BMI and maternal BMI (mBMI), and BMI was significantly associated with QS. CONCLUSIONS Our results suggest that cortisol and cortisone levels are associated with overweight in children, but the 11β-HSD2 activities showed no significant differences. Unhealthy family diet was associated with higher BMI, UF, and UE, and families with maternal overweight or obesity had a higher prevalence of children's overweight or obesity.

Using Genetic Variation to Explore the Causal Effect of Maternal Pregnancy Adiposity on Future Offspring Adiposity: A Mendelian Randomisation Study

BACKGROUND

It has been suggested that greater maternal adiposity during pregnancy affects lifelong risk of offspring fatness via intrauterine mechanisms. Our aim was to use Mendelian randomisation (MR) to investigate the causal effect of intrauterine exposure to greater maternal body mass index (BMI) on offspring BMI and fat mass from childhood to early adulthood.

METHODS AND FINDINGS

We used maternal genetic variants as instrumental variables (IVs) to test the causal effect of maternal BMI in pregnancy on offspring fatness (BMI and dual-energy X-ray absorptiometry [DXA] determined fat mass index [FMI]) in a MR approach. This was investigated, with repeat measurements, from ages 7 to 18 in the Avon Longitudinal Study of Parents and Children (ALSPAC; n = 2,521 to 3,720 for different ages). We then sought to replicate findings with results for BMI at age 6 in Generation R (n = 2,337 for replication sample; n = 6,057 for total pooled sample). In confounder-adjusted multivariable regression in ALSPAC, a 1 standard deviation (SD, equivalent of 3.7 kg/m2) increase in maternal BMI was associated with a 0.25 SD (95% CI 0.21-0.29) increase in offspring BMI at age 7, with similar results at later ages and when FMI was used as the outcome. A weighted genetic risk score was generated from 32 genetic variants robustly associated with BMI (minimum F-statistic = 45 in ALSPAC). The MR results using this genetic risk score as an IV in ALSPAC were close to the null at all ages (e.g., 0.04 SD (95% CI -0.21-0.30) at age 7 and 0.03 SD (95% CI -0.26-0.32) at age 18 per SD increase in maternal BMI), which was similar when a 97 variant generic risk score was used in ALSPAC. When findings from age 7 in ALSPAC were meta-analysed with those from age 6 in Generation R, the pooled confounder-adjusted multivariable regression association was 0.22 SD (95% CI 0.19-0.25) per SD increase in maternal BMI and the pooled MR effect (pooling the 97 variant score results from ALSPAC with the 32 variant score results from Generation R) was 0.05 SD (95%CI -0.11-0.21) per SD increase in maternal BMI (p-value for difference between the two results = 0.05). A number of sensitivity analyses exploring violation of the MR results supported our main findings. However, power was limited for some of the sensitivity tests and further studies with relevant data on maternal, offspring, and paternal genotype are required to obtain more precise (and unbiased) causal estimates.

CONCLUSIONS

Our findings provide little evidence to support a strong causal intrauterine effect of incrementally greater maternal BMI resulting in greater offspring adiposity.

Influence of Maternal Gestational Hypertensive Disorders on Microvasculature in School-Age Children: The Generation R Study

Gestational hypertensive disorders may lead to vascular changes in the offspring. We examined the associations of maternal blood pressure development and hypertensive disorders during pregnancy with microvasculature adaptations in the offspring in childhood. This study was performed as part of the Generation R Study in Rotterdam, the Netherlands (2002-2012), among 3,748 pregnant mothers and their children for whom information was available on maternal blood pressure in different periods of pregnancy and gestational hypertensive disorders. Childhood retinal arteriolar and venular calibers were assessed at the age of 6 years. We found that higher maternal systolic and diastolic blood pressures in early pregnancy were associated with childhood retinal arteriolar narrowing (P < 0.05). Higher maternal systolic blood pressure in late pregnancy, but not in middle pregnancy, was associated with childhood narrower retinal venular caliber (standard deviation score per standardized residual increase in systolic blood pressure: -0.05; 95% confidence interval: -0.08, -0.01). Paternal blood pressure was not associated with childhood retinal vessel calibers. Children of mothers with gestational hypertensive disorders tended to have narrower retinal arteriolar caliber (standard deviation score: -0.13, 95% confidence interval: -0.27, 0.01). Our results suggest that higher maternal blood pressure during pregnancy is associated with persistent microvasculature adaptations in their children. Further studies are needed to replicate these observations.

Maternal pre-pregnancy body mass index and newborn telomere length

BACKGROUND

Newborn telomere length sets telomere length for later life. At birth, telomere length is highly variable among newborns and the environmental factors during in utero life for this observation remain largely unidentified. Obesity during pregnancy might reflect an adverse nutritional status affecting pregnancy and offspring outcomes, but the association of maternal pre-pregnancy body mass index (BMI) with newborn telomere length, as a mechanism of maternal obesity, on the next generation has not been addressed.

METHODS

Average relative telomere lengths were measured in cord blood (n = 743) and placental tissue (n = 702) samples using a quantitative real-time PCR method from newborns from the ENVIRONAGE birth cohort in Belgium. By using univariate and multivariable adjusted linear regression models we addressed the associations between pre-pregnancy BMI and cord blood and placental telomere lengths.

RESULTS

Maternal age was 29.1 years (range, 17-44) and mean (SD) pre-pregnancy BMI was 24.1 (4.1) kg/m². Decline in newborn telomere length occurred in parallel with higher maternal pre-pregnancy BMI. Independent of maternal and paternal age at birth, maternal education, gestational age, newborn gender, ethnicity, birthweight, maternal smoking status, parity, cesarean section, and pregnancy complications, each kg/m² increase in pre-pregnancy BMI was associated with a -0.50 % (95 % CI, -0.83 to -0.17 %; P = 0.003) shorter cord blood telomere length and a -0.66 % (95 % CI, -1.06 to -0.25 %; P = 0.002) shorter placental telomere length.

CONCLUSIONS

Maternal pre-pregnancy BMI is associated with shorter newborn telomere lengths as reflected by cord blood and placental telomeres. These findings support the benefits of a pre-pregnancy healthy weight for promoting molecular longevity from early life onwards.

Maternal pre-pregnancy body mass index and newborn telomere length

BACKGROUND

Newborn telomere length sets telomere length for later life. At birth, telomere length is highly variable among newborns and the environmental factors during in utero life for this observation remain largely unidentified. Obesity during pregnancy might reflect an adverse nutritional status affecting pregnancy and offspring outcomes, but the association of maternal pre-pregnancy body mass index (BMI) with newborn telomere length, as a mechanism of maternal obesity, on the next generation has not been addressed.

METHODS

Average relative telomere lengths were measured in cord blood (n = 743) and placental tissue (n = 702) samples using a quantitative real-time PCR method from newborns from the ENVIRONAGE birth cohort in Belgium. By using univariate and multivariable adjusted linear regression models we addressed the associations between pre-pregnancy BMI and cord blood and placental telomere lengths.

RESULTS

Maternal age was 29.1 years (range, 17-44) and mean (SD) pre-pregnancy BMI was 24.1 (4.1) kg/m². Decline in newborn telomere length occurred in parallel with higher maternal pre-pregnancy BMI. Independent of maternal and paternal age at birth, maternal education, gestational age, newborn gender, ethnicity, birthweight, maternal smoking status, parity, cesarean section, and pregnancy complications, each kg/m² increase in pre-pregnancy BMI was associated with a -0.50 % (95 % CI, -0.83 to -0.17 %; P = 0.003) shorter cord blood telomere length and a -0.66 % (95 % CI, -1.06 to -0.25 %; P = 0.002) shorter placental telomere length.

CONCLUSIONS

Maternal pre-pregnancy BMI is associated with shorter newborn telomere lengths as reflected by cord blood and placental telomeres. These findings support the benefits of a pre-pregnancy healthy weight for promoting molecular longevity from early life onwards.

Parental pre-pregnancy BMI influences on offspring BMI and waist circumference at 21 years

OBJECTIVES

To investigate the prospective association between parental pre-pregnancy BMI and adult male and female offspring BMI and waist circumference (WC).

METHODS

Sub-sample of 2,229 parent-offspring pairs with parental pre-pregnancy BMI and offspring BMI and WC at 21 years were used from the MUSP (Mater-University of Queensland Study of Pregnancy cohort). Multivariable results were adjusted for maternal factors around pregnancy (e.g. gestational weight and smoking during pregnancy) and offspring factors in early life (e.g. birth weight) and at 14 years (e.g. sports participation and mealtime with family).

RESULTS

After adjustments for confounders, each unit increase in paternal and maternal BMI, the BMI of young adult offspring increased by 0.33kg/m² and 0.35kg/m² , and the WC increased by 0.76 cm and 0.62 cm, respectively. In the combination of parents' weight status, offspring at 21 years were six times the risk being overweight/obese (OW/OB) when both parents were OW/OB, compared to offspring of healthy weight parents.

CONCLUSIONS

Prenatal parental BMI are independently related to adult offspring BMI and WC.

IMPLICATIONS

Both prenatal paternal-maternal weight status are important determinants of offspring weight status in long-term. Further studies are warranted to investigate the underlying mechanisms.