Maternal Birth Weight and BMI Mediate the Transgenerational Effect of Grandmaternal BMI on Grandchild's Birth Weight

Grandmaternal prepregnancy body mass index and infant birthweight: a mediation analysis of maternal prepregnancy body mass index

The objectives of this study were to examine the total effect of grandmaternal (G0) prepregnancy body mass index (BMI) on infant (G2) birthweight z score and to quantify the mediation role of maternal (G1) prepregnancy BMI. Data were extracted from the Nova Scotia 3G Multigenerational Cohort. The association between G0 prepregnancy BMI and G2 birthweight z score and the mediated effect by G1 prepregnancy BMI were estimated using g-computation with adjustment for confounders identified using a directed acyclic graph and accounting for intermediate confounding. A total of 20 822 G1-G2 dyads from 18 450 G0 participants were included. Relative to G0 normal weight, G0 underweight decreased mean G2 birthweight z score (-0.11; 95% CI, -0.20 to -0.030), whereas G0 overweight and obesity increased mean G2 birthweight z score (0.091 [95% CI, 0.034-0.15] and 0.22 [95% CI, 0.11-0.33], respectively). G1 prepregnancy BMI partly mediated the association, with the largest effect size observed for G0 obesity (0.11; 95% CI, 0.080-0.14). Estimates of the direct effect were close to the null. In conclusion, grandmaternal prepregnancy BMI was associated with infant birthweight z score. Maternal prepregnancy BMI partly mediated the association, suggesting that factors related to BMI may play an important role in the transmission of weight across the maternal line.

Grandmaternal body mass index in early pregnancy and risk of grandoffspring stillbirth: a nationwide, 3-generation cohort study

We investigated the association between maternal grandmaternal early pregnancy body mass index (BMI) and grandoffspring stillbirth risk in a Swedish population-based 3-generation cohort of 176 908 grandmothers (F0), 197 579 mothers (F1), and 316 459 grandoffspring (F2) born 1997-2016. There were 998 stillbirths (risk, 3.2 per 1000 births). Compared with grandmaternal BMI 18.5-24.9, adjusted relative risks (RRs) of grandoffspring stillbirth for BMIs of 25.0-29.9 and ≥30.0 were, respectively, 1.41 (95% CI, 1.15-1.72) and 1.62 (95% CI, 1.14-2.30). RRs for corresponding maternal (F1) BMI categories were, respectively, 1.32 (95% CI, 1.06-1.65) and 1.77 (95% CI, 1.39-2.25). Maternal BMI mediated only 19% of this relationship. Grandmaternal preeclampsia and maternal small-for-gestational age (SGA) birth were related to increased F2 stillbirth risk but did not mediate the association between grandmaternal BMI and grandoffspring stillbirth risk. To explore whether this association was explained by factors shared within families, we studied the relationship of maternal full sisters' BMI and stillbirth risk in 101 368 pregnancies. Stillbirth RRs for full sisters' BMI 25.0-29.9 and ≥30.0 compared with 18.5-24.9 were, respectively, 0.76 (95% CI, 0.51-1.13) and 0.88 (95% CI, 0.55-1.40). In conclusion, grandmaternal overweight and obesity were associated with grandoffspring stillbirth. This association is not fully explained by shared familial factors.

The influence of intergenerational trauma on epigenetics and obesity in Indigenous populations - a scoping review

Background: Research has recently begun to examine the potential intergenerational impacts of trauma on obesity.Objective: This scoping review examines the literature on the interactions between intergenerational trauma, epigenetics, and obesity in Indigenous populations. The review was conducted to identify what is known from the literature about how intergenerational trauma may epigenetically influence obesity in Indigenous populations.Methods: Following the PRISMA-ScR guidelines for scoping reviews, online databases were used to identify studies that included discussion of the four focus topics: trauma, epigenetics, obesity, and Indigeneity. The review resulted in six studies that examined those themes. The focus and findings of the selected studies varied from cultural to biological mechanisms and from discussion regarding trauma, epigenetics, obesity, or Indigeneity, but they support three broad statements. First, they support that obesity has genetic and epigenetic factors. Second, intergenerational trauma is prevalent in Indigenous communities. Finally, intergenerational trauma has cultural and biological influences on obesity.Conclusions: Current literature illustrates that intergenerational trauma has behavioural and epigenetic influences that can lead to increased obesity. This scoping review provides a preliminary map of the current literature and understandings of these topics. This review calls for continued studies regarding the connection between trauma, obesity, and epigenetics in Indigenous communities. Future research is vital for practice and policy surrounding individual and communal healing.

The role of epigenetics in multi-generational transmission of asthma: An NIAID workshop report-based narrative review

There is mounting evidence that environmental exposures can result in effects on health that can be transmitted across generations, without the need for a direct exposure to the original factor, for example, the effect of grandparental smoking on grandchildren. Hence, an individual's health should be investigated with the knowledge of cross-generational influences. Epigenetic factors are molecular factors or processes that regulate genome activity and may impact cross-generational effects. Epigenetic transgenerational inheritance has been demonstrated in plants and animals, but the presence and extent of this process in humans are currently being investigated. Experimental data in animals support transmission of asthma risk across generations from a single exposure to the deleterious factor and suggest that the nature of this transmission is in part due to changes in DNA methylation, the most studied epigenetic process. The association of father's prepuberty exposure with offspring risk of asthma and lung function deficit may also be mediated by epigenetic processes. Multi-generational birth cohorts are ideal to investigate the presence and impact of transfer of disease susceptibility across generations and underlying mechanisms. However, multi-generational studies require recruitment and assessment of participants over several decades. Investigation of adult multi-generation cohorts is less resource intensive but run the risk of recall bias. Statistical analysis is challenging given varying degrees of longitudinal and hierarchical data but path analyses, structural equation modelling and multilevel modelling can be employed, and directed networks addressing longitudinal effects deserve exploration as an effort to study causal pathways.

Multigenerational transmission of obesity: A systematic review and meta-analysis

There is a strong link between parental and offspring obesity status. However, the state of epidemiological evidence on multigenerational transmission of overweight/obesity, such as from grandparents to grandchildren, is relatively unknown. This systematic review collates and appraises existing evidence on multigenerational transmission of overweight/obesity and uses meta-analytic estimates for quantitative synthesis. Six electronic databases were searched for publications reporting the relationship between grandparents and their grandchildren overweight/obesity status. A total of 25 studies from 17 countries with a combined population of 238,771 study participants met the inclusion criteria. About 60% (15) of the reviewed studies reported a positive association between grandparent-grandchild (GP-GC) overweight/obesity, out of which 11 were statistically significant. Seven studies reported odds ratios of GP-GC overweight/obesity associations and were included in the meta-analysis. The pooled estimates showed a significant GP-GC association in overweight/obesity status (odds ratio [OR]: 1.79, 95% confidence interval [CI]: 1.01-2.57). Thus, the current research evidence shows that grandchildren's overweight/obesity status is associated with their grandparents' overweight/obesity status, indicating a multigenerational transmission of obesity. However, more studies, especially from developing countries, are required to assess the robustness of these findings. Future studies should also focus on the mechanisms through which this transmission occurs.

The Impact of Early-Life Exposures on Women's Reproductive Health in Adulthood

Purpose of Review

To review the effects of early-life, preconception, and prior-generation exposures on reproductive health in women.

Recent Findings

Women’s early-life factors can affect reproductive health by contributing to health status or exposure level on entering pregnancy. Alternately, they can have permanent effects, regardless of later-life experience. Nutrition, social class, parental smoking, other adverse childhood experiences, environmental pollutants, infectious agents, and racism and discrimination all affect reproductive health, even if experienced in childhood or in utero. Possible transgenerational effects are now being investigated through three- or more-generation studies. These effects occur with mechanisms that may include direct exposure, behavioral, endocrine, inflammatory, and epigenetic pathways.

Summary

Pregnancy is increasingly understood in a life course perspective, but rigorously testing hypotheses on early-life effects is still difficult. In order to improve the health outcomes of all women, we need to expand our toolkit of methods and theory.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40471-021-00279-0.

Decreased Fatty Acid Transporter FABP1 and Increased Isoprostanes and Neuroprostanes in the Human Term Placenta: Implications for Inflammation and Birth Weight in Maternal Pre-Gestational Obesity

The rise in prevalence of obesity in women of reproductive age in developed and developing countries might propagate intergenerational cycles of detrimental effects on metabolic health. Placental lipid metabolism is disrupted by maternal obesity, which possibly affects the life-long health of the offspring. Here, we investigated placental lipid metabolism in women with pre-gestational obesity as a sole pregnancy complication and compared it to placental responses of lean women. Open profile and targeted lipidomics were used to assess placental lipids and oxidised products of docosahexaenoic (DHA) and arachidonic acid (AA), respectively, neuroprostanes and isoprostanes. Despite no overall signs of lipid accumulation, DHA and AA levels in placentas from obese women were, respectively, 2.2 and 2.5 times higher than those from lean women. Additionally, a 2-fold increase in DHA-derived neuroprostanes and a 1.7-fold increase in AA-derived isoprostanes were seen in the obese group. These changes correlated with a 70% decrease in placental FABP1 protein. Multivariate analyses suggested that neuroprostanes and isoprostanes are associated with maternal and placental inflammation and with birth weight. These results might shed light on the molecular mechanisms associated with altered placental fatty acid metabolism in maternal pre-gestational obesity, placing these oxidised fatty acids as novel mediators of placental function.

Exploring the evidence for epigenetic regulation of environmental influences on child health across generations

Environmental exposures, psychosocial stressors and nutrition are all potentially important influences that may impact health outcomes directly or via interactions with the genome or epigenome over generations. While there have been clear successes in large-scale human genetic studies in recent decades, there is still a substantial amount of missing heritability to be elucidated for complex childhood disorders. Mounting evidence, primarily in animals, suggests environmental exposures may generate or perpetuate altered health outcomes across one or more generations. One putative mechanism for these environmental health effects is via altered epigenetic regulation. This review highlights the current epidemiologic literature and supporting animal studies that describe intergenerational and transgenerational health effects of environmental exposures. Both maternal and paternal exposures and transmission patterns are considered, with attention paid to the attendant ethical, legal and social implications.