Gillian England-Mason

Introduction: Pregnancy is a critical period for fetal brain development and is sensitive to maternal micronutrient status. Maternal vitamin D [25(OH)D] concentrations have been associated with child neurodevelopmental outcomes, while biological aging processes reflected by epigenetic age acceleration (EAA) may contribute to these associations. This study examined associations between maternal vitamin D concentrations and neurodevelopmental outcomes in preschool-aged children and explored whether infant EAA mediated these associations. Methods: We included 252 mother-child pairs from the APrON cohort. Maternal second trimester plasma 25(OH)D ₃ concentrations were quantified, and children's cognitive, language, motor, and behavioural outcomes were assessed at 3–5-years. In a subsample of 130 children, buccal epithelial cells collected at 3 months were profiled using the Infinium HumanMethylation EPIC v1.0 BeadChip. EAA was estimated using the Pediatric-Buccal-Epigenetic clock. Adjusted linear regressions examined associations between maternal 25(OH)D ₃ and children's outcomes, including models using quartiles and a 30 ng/mL threshold. Mann–Whitney U -tests compared outcomes according to a 20 ng/mL sufficiency threshold. In the subsample, exploratory mediation analyses examined the potential mediating role of infant EAA. Results: No associations were found between maternal vitamin D and children's cognitive, language, or behavioural outcomes. Maternal vitamin D concentrations were positively associated with children's motor outcomes ( B = 0.04; 95% CI = 0.004, 0.076, p = 0.03), although this small, nominal association did not survive correction for multiple comparisons ( q = 0.18). This positive association was attenuated when vitamin D was modeled using quartiles or when “sufficiency” was defined as 30 ng/mL. No differences were found in neurodevelopmental outcomes based on vitamin D sufficiency defined as 20 ng/mL. No evidence of mediation via EAA was detected, although small indirect effects could have gone undetected due to the small sample size for this sub-analysis. Conclusions: This study provides preliminary evidence that maternal vitamin D concentrations during pregnancy are associated with improved motor performance in children. A biomarker of biological aging, EAA, did not appear to play a role in this association. Examination of different forms of maternal vitamin D and statistical models that consider continuous measures and thresholds of “sufficiency” are needed to clarify associations between maternal vitamin D concentrations and children's neurodevelopment.

Associations between prenatal exposure to phthalates, bisphenols and their mixtures and early childhood allergic conditions and asthma were examined. Five hundred and fifty-six mother–child pairs from the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort participated. Urine samples collected from mothers during the second trimester of pregnancy were analyzed for phthalates and bisphenols. A child health questionnaire, completed by mothers when children were 12, 24, and 36 months, asked whether children had experienced allergic conditions (i.e., food allergies, eczema, rash) or asthma. In single-chemical models, associations varied with child age. Higher prenatal concentrations of mono-benzyl phthalate (MBzP) were associated with lower odds of eczema at 12 months. At 36 months, higher mono-methyl phthalate (MMP) was associated with increased odds of eczema, whereas higher mono-carboxy-octyl phthalate (MCOP) was associated with reduced odds. Higher prenatal MCOP was also associated with higher odds of rash at 12 months, and higher MMP was associated with higher odds of rash at 36 months. Higher bisphenol S (BPS) was associated with increased odds of asthma at 12 months but decreased odds of eczema and rash at 36 months. Sex-specific effects were also noted. In multi-chemical exposure least absolute shrinkage and selection operator (LASSO) models, several phthalate metabolites and BPS were selected as the best predictors of eczema and rash at 36 months of age. Bayesian kernel machine regression (BKMR) mixture models suggested that BPS was the most important chemical in predicting eczema in children at 36 months, while MMP and BPS were the most important chemicals in predicting rash at 36 months. Prenatal exposure to certain phthalate metabolites and BPS predicted allergic conditions and asthma in young children, with patterns varying by age and sex. Prenatal exposure to these chemicals may differentially influence immune development and contribute to the development of early-life allergic conditions, with potentially sex-specific susceptibility.

In pregnancy, wholefood diets with an anti-inflammatory profile may influence long-term brain development through epigenetic modifications, particularly DNA methylation. Since DNA methylation signatures associated with children’s cognition and language development are likely multifactorial, an advanced epigenetic network approach is required to assess multiple CpG patterns and their underlying influences. Here we investigated a cognition-related co-methylation (Co-MN ^cog1 ) network using weighted gene co-expression network analysis. Genes significantly enriched in the Co-MN ^cog1 network were related to neural function, plasticity and synapse formation. Using a longitudinal population-derived cohort (Barwon Infant Study, N=562 mother-child pairs), we found that the maternal wholefood dietary pattern was associated with a higher Co-MN ^cog1 network (p=0.001) and higher offspring Bayley-III cognitive scores (pcog1 network (p=0.005) and lower offspring cognitive score (pcog1 network partially mediated the following associations: (i) higher prenatal wholefood dietary pattern and higher children’s cognitive (percentage mediated=10%, p=0.038) and receptive language (percentage mediated=7%, p=0.042) scores at age 2 years, and (ii) higher prenatal dietary inflammatory index and lower children’s cognitive (percentage mediated=9%, p=0.050) and receptive language (percentage mediated=8%, p=0.040) scores at age 2 years. Importantly, we confirmed that the Co-MN ^cog1 network was associated (p=0.015) with children’s Bayley-III social-emotional outcomes at age 2 years in an external cohort. These results highlight the central role of prenatal diet in shaping children’s cognition, language and social-emotional development through epigenetic modification, and identified possible pathways implicated in fetal neurodevelopment.

Following a variety of early environmental experiences and exposures, epigenetic modifications such as DNA methylation are proposed as candidate mechanisms that contribute to health and disease across the lifespan. Epigenetic clocks are a type of aging biomarker that can offer insight into age-related changes associated with early environmental exposures. This review provides a brief overview of epigenetic clocks that are readily available for use with perinatal and/or pediatric samples, as well as highlights some recent research that has studied the associations between early environmental chemical exposures and epigenetic aging rates. Broadly, the easily accessible epigenetic clocks can be categorized as chronological age estimators and gestational age estimators, but some clocks were developed for use with specific tissues and/or age groups. Previous environmental epidemiology studies have shown that early environmental exposures such as air pollutants and endocrine-disrupting chemicals are associated with altered epigenetic aging rates in perinatal and pediatric populations. However, more research is needed that examines how factors such as exposure level, timing of exposure, and sex may affect the direction and magnitude of associations. This review concludes with some recommendations and future directions for the use of epigenetic clocks in environmental epigenetics. Overall, epigenetic clocks are promising, non-causal biomarkers of early exposures that can be examined in relation to environmental chemicals, health and disease outcomes, and as biological mediators. Future research could help determine whether these clocks hold promise as informative biomarkers that reflect developmental epigenotoxicity following early exposure to environmental chemicals.

We examined whether prenatal exposure to two classes of endocrine-disrupting chemicals (EDCs) was associated with infant epigenetic age acceleration (EAA), a DNA methylation biomarker of aging. Participants included 224 maternal–infant pairs from a Canadian pregnancy cohort study. Two bisphenols and 12 phthalate metabolites were measured in maternal second trimester urines. Buccal epithelial cell cheek swabs were collected from 3 month old infants and DNA methylation was profiled using the Infinium MethylationEPIC BeadChip. The Pediatric-Buccal-Epigenetic tool was used to estimate EAA. Sex-stratified robust regressions examined individual chemical associations with EAA, and Bayesian kernel machine regression (BKMR) examined chemical mixture effects. Adjusted robust models showed that in female infants, prenatal exposure to total bisphenol A (BPA) was positively associated with EAA (B = 0.72, 95% CI: 0.21, 1.24), and multiple phthalate metabolites were inversely associated with EAA (Bs from −0.36 to −0.66, 95% CIs from −1.28 to −0.02). BKMR showed that prenatal BPA was the most important chemical in the mixture and was positively associated with EAA in both sexes. No overall chemical mixture effects or male-specific associations were noted. These findings indicate that prenatal EDC exposures are associated with sex-specific deviations in biological aging, which may have lasting implications for child health and development.

Di(2-ethylhexyl) phthalate (DEHP) is a common plasticizer that can affect immune system development and susceptibility to infection. Aging processes (measured as epigenetic age acceleration (EAA)) may mediate the immune-related effects of prenatal exposure to DEHP. This study’s objective was to examine associations between prenatal DEHP exposure, EAA at three months of age, and the number of upper respiratory infections (URIs) from 12 to 18 months of age using a sample of 69 maternal–child pairs from a Canadian pregnancy cohort. Blood DNA methylation data were generated using the Infinium HumanMethylation450 BeadChip; EAA was estimated using Horvath’s pan-tissue clock. Robust regressions examined overall and sex-specific associations. Higher prenatal DEHP exposure (B = 6.52, 95% CI = 1.22, 11.81) and increased EAA (B = 2.98, 95% CI = 1.64, 4.32) independently predicted more URIs. In sex-specific analyses, some similar effects were noted for boys, and EAA mediated the association between prenatal DEHP exposure and URIs. In girls, higher prenatal DEHP exposure was associated with decreased EAA, and no mediation was noted. Higher prenatal DEHP exposure may be associated with increased susceptibility to early childhood URIs, particularly in boys, and aging biomarkers such as EAA may be a biological mechanism. Larger cohort studies examining the potential developmental immunotoxicity of phthalates are needed.