Associations between maternal age and socioeconomic status with smoking during the second and third trimesters of pregnancy: a register-based study of 932 671 women in Finland from 2000 to 2015

Explaining how childhood physical abuse and physical neglect influence adult depression: An analysis with multiple sequential mediators

BACKGROUND

Substantial evidence indicates that experiencing physical abuse and neglect during childhood significantly elevates the likelihood of developing depression in adulthood. Nevertheless, there remains a dearth of understanding regarding the mechanisms underpinning this correlation.

OBJECTIVE

In this study, we aimed to examine the associations of childhood physical abuse and physical neglect with depression using follow-up data from UK Biobank and quantified the contribution of smoking, insomnia, and BMI in these associations.

PARTICIPANTS AND SETTINGS

This study included 144,704 participants (64,168 men and 80,536 women) from UK Biobank, most of whom were white (97 %).

METHODS

Physical abuse and physical neglect were measured using two items of Childhood Trauma Screener (CTS). Data on the incidence of depression were obtained from primary care, hospital inpatient records, self-reported medical conditions, and death registries. We used a sequential mediation analysis based on the "g-formula" approach to explore the individual and joint effects of potential mediators.

RESULTS

The depression incidence rate was 1.85 per 1000 person-years for men and 2.83 per 1000 person-years for women, respectively. Results of Cox proportional risk regression showed that physical abuse (HRs: 1.39-1.53, P < 0.001) and physical neglect (HRs: 1.43-1.60, P < 0.001) are associated with depression. Smoking, insomnia, and BMI together mediated 3 %-26 % of the associations.

CONCLUSIONS

These findings contribute to our understanding of how physical abuse and physical neglect influence depression. Furthermore, a more effective reduction in the burden of depression can be achieved by managing modifiable mediators.

Epigenetics of the non-coding RNA nc886 across blood, adipose tissue and skeletal muscle in offspring exposed to diabetes in pregnancy

BACKGROUND

Diabetes in pregnancy is associated with increased risk of long-term metabolic disease in the offspring, potentially mediated by in utero epigenetic variation. Previously, we identified multiple differentially methylated single CpG sites in offspring of women with gestational diabetes mellitus (GDM), but whether stretches of differentially methylated regions (DMRs) can also be identified in adolescent GDM offspring is unknown. Here, we investigate which DNA regions in adolescent offspring are differentially methylated in blood by exposure to diabetes in pregnancy. The secondary aim was to characterize the RNA expression of the identified DMR, which contained the nc886 non-coding RNA.

METHODS

To identify DMRs, we employed the bump hunter method in samples from young (9-16 yr, n = 92) offspring of women with GDM (O-GDM) and control offspring (n = 94). Validation by pyrosequencing was performed in an adult offspring cohort (age 28-33 years) consisting of O-GDM (n = 82), offspring exposed to maternal type 1 diabetes (O-T1D, n = 67) and control offspring (O-BP, n = 57). RNA-expression was measured using RT-qPCR in subcutaneous adipose tissue and skeletal muscle.

RESULTS

One significant DMR represented by 10 CpGs with a bimodal methylation pattern was identified, located in the nc886/VTRNA2-1 non-coding RNA gene. Low methylation status across all CpGs of the nc886 in the young offspring was associated with maternal GDM. While low methylation degree in adult offspring in blood, adipose tissue, and skeletal muscle was not associated with maternal GDM, adipose tissue nc886 expression was increased in O-GDM compared to O-BP, but not in O-T1D. In addition, adipose tissue nc886 expression levels were positively associated with maternal pre-pregnancy BMI (p = 0.006), but not with the offspring's own adiposity.

CONCLUSIONS

Our results highlight that nc886 is a metastable epiallele, whose methylation in young offspring is negatively correlated with maternal obesity and GDM status. The physiological effect of nc886 may be more important in adipose tissue than in skeletal muscle. Further research should aim to investigate how nc886 regulation in adipose tissue by exposure to GDM may contribute to development of metabolic disease.

How are socioeconomic inequalities in preterm birth explained by maternal smoking and maternal body mass index: A mediation analysis

BACKGROUND

Preterm birth affects between 7% and 8% of births in the UK and is a leading cause of infant mortality and childhood disability. Prevalence of preterm birth has been shown to have significant and consistent socioeconomic inequalities.

OBJECTIVE

To estimate how much of the association between socioeconomic status (SES) and gestational age at birth is mediated by maternal smoking status and maternal body mass index (BMI).

METHODS

Retrospective cohort study of a maternity hospital in the UK. The analysis included all singleton live births between April 2009 and March 2020 to mothers 18 years old and over, between 22 weeks and 43 weeks gestation. We estimate two measures of mediation for four low gestational age categories: (i) The proportion eliminated the percentage of the effect of SES on low gestational age at birth that would be eliminated by removing the mediators, through the Controlled Direct Effects estimated using serial log-binomial regressions; and (ii) The proportion mediated is the percentage of the effect removed by equalising the distribution of the mediators across socioeconomic groups, estimated using Interventional Disparity Measures calculated through Monte Carlo simulations.

RESULTS

Overall, 81,219 births were included, with 63.7% low SES. The risk of extremely (0.3% of all births), very (0.7%) and moderately preterm birth (6.3%) was 1.71 (95% Confidence Interval [CI] 1.29, 2.31), 1.43 (95% CI 1.18, 1.73) and 1.26 (95% CI 1.19, 1.34) times higher in the low SES, compared to higher SES respectively. The proportion of this inequality eliminated by removing both maternal smoking and BMI was 43.4% for moderately preterm births. The proportion mediated for smoking was 33.9%, 43.0% and 48.4% respectively.

CONCLUSIONS

Smoking during pregnancy is a key mediator of inequalities in preterm birth, representing an area for local action to reduce social inequalities in preterm birth.

Prevalence of smoking during pregnancy and associated social inequalities in developed countries over the 1995-2020 period: A systematic review

BACKGROUND

Smoking during pregnancy (SDP) is an important source of preventable morbidity and mortality for both mother and child.

OBJECTIVES

The aim of this study was to describe changes in the prevalence of SDP over the last 25 years in developed countries (Human Development Index >0.8 in 2020) and associated social inequalities.

DATA SOURCES

A systematic review was conducted based on a search in PubMed, Embase and PsycInfo databases and government sources.

STUDY SELECTION AND DATA EXTRACTION

Published studies between January 1995 and March 2020, for which the primary outcome was to assess the national prevalence of SDP and the secondary outcome was to describe related socio-economic data were included in the analysis. The selected articles had to be written in English, Spanish, French or Italian.

SYNTHESIS

The articles were selected after successive reading of the titles, abstracts and full-length text. An independent double reading with intervention of a third reader in case of disagreement allowed including 35 articles from 14 countries in the analysis.

RESULTS

The prevalence of SDP differed across the countries studied despite comparable levels of development. After 2015, the prevalence of SDP ranged between 4.2% in Sweden and 16.6% in France. It was associated with socio-economic factors. The prevalence of SDP slowly decreased over time, but this overall trend masked inequalities within populations. In Canada, France and the United States, the prevalence decreased more rapidly in women of higher socio-economic status, and inequalities in maternal smoking were more marked in these countries. In the other countries, inequalities tended to decrease but remained significant.

CONCLUSIONS

During pregnancy, that is a period described as a window of opportunity, smoking and social vulnerability factors need to be detected to implement targeted prevention strategies aiming at reducing related social inequalities.

Socioeconomic status, maternal risk factors, and gestational diabetes mellitus across reproductive years: a Finnish register-based study

INTRODUCTION

To evaluate the degree to which socioeconomic differences in gestational diabetes mellitus (GDM) are accounted for by differences in maternal risk factors, to assess whether age-related risks of GDM differ across socioeconomic groups, and to identify priority populations for future interventions.

RESEARCH DESIGN AND METHODS

We performed a register-based study using data from the Finnish Medical Birth Register and Statistics Finland on the 474 166 women who gave birth in Finland from 2008 to 2015. We collected information on GDM based on the International Classification of Diseases 10th Revision codes O24.4 and O24.9. We used multivariable models to examine the association between socioeconomic status, maternal risk factors, and GDM. We further tested interaction on multiplicative and additive scales.

RESULTS

The incidence of GDM was 8.7% in 2008-2011 and 12.5% in 2012-2015. Lower socioeconomic levels than upper level employees were associated with an increased risk of GDM. Up to 64.0% of socioeconomic differences in GDM were attributed to body mass index and 5.5% to smoking. There was evidence for effect modification. Relative to women in the upper level category who were aged less than 19 years, GDM adjusted ORs (95% CIs) for women 35 years or older in upper level versus long-term unemployed groups were 3.28 (2.08-5.18) and 5.29 (3.35-8.35), respectively.

CONCLUSIONS

There is a paradox that socioeconomic advantage increases the incidence of GDM at the population level while reducing the incidence of GDM within the population. Nevertheless, socioeconomic differences in GDM persist and widen with increasing maternal age, even after accounting for maternal risk factors.

Association between maternal e-cigarette use during pregnancy and low gestational weight gain

OBJECTIVE

To evaluate the risk of low gestational weight gain (GWG) in women who use electronic cigarettes (e-cigarettes), combustible cigarettes, or both e-cigarettes and combustible cigarettes (dual use) during pregnancy.

METHODS

We conducted a secondary analysis of the data from 176 882 singleton pregnancies in the 2016-2020 US Pregnancy Risk Assessment Monitoring System (PRAMS). Postpartum women self-reported their use of e-cigarettes and/or cigarettes during the last 3 months of pregnancy. Low GWG was defined as the total GWG less than 12.7 kg, less than 11.3 kg, less than 6.8 kg, and less than 5.0 kg (<28, <25, <15, and < 11 lb) for women with underweight, normal weight, overweight, and obesity, respectively. We used multivariable logistic regression to estimate the odds ratios (ORs) of low GWG, adjusting for confounders.

RESULTS

In this national sample, 921 (weighted percentage, 0.5%) of women were e-cigarette users and 1308 (0.7%) were dual users during late pregnancy. Compared with non-users during late pregnancy (40 090, 22.1%), cigarette users (4499, 28.0%) and dual users (427, 26.0%) had a higher risk of low GWG, but e-cigarette users had a similar risk (237, 22.1%). Adjustment for sociodemographic and pregnancy confounders moderately attenuated these associations: confounder-adjusted ORs 1.26 (95% confidence interval [CI] 1.18-1.35) for cigarette users, 1.18 (95% CI 0.96-1.44) for dual users, and 0.99 (95% CI 0.78-1.27) for e-cigarette users.

CONCLUSIONS

Unlike combustible cigarette use, e-cigarette use during late pregnancy does not appear to be a risk factor for low GWG.

Association of Preterm Birth and Socioeconomic Status With Neonatal Brain Structure

Importance

Preterm birth and socioeconomic status (SES) are associated with brain structure in childhood, but the relative contributions of each during the neonatal period are unknown.

Objective

To investigate associations of birth gestational age (GA) and SES with neonatal brain morphology by testing 3 hypotheses: GA and SES are associated with brain morphology; associations between SES and brain morphology vary with GA; and associations between SES and brain structure and morphology depend on how SES is operationalized.

Design, Setting, and Participants

This cohort study recruited participants from November 2016 to September 2021 at a single center in the United Kingdom. Participants were 170 extremely and very preterm infants and 91 full-term or near-term infants. Exclusion criteria were major congenital malformation, chromosomal abnormality, congenital infection, cystic periventricular leukomalacia, hemorrhagic parenchymal infarction, and posthemorrhagic ventricular dilatation.

Exposures

Birth GA and SES, operationalized at the neighborhood level (using the Scottish Index of Multiple Deprivation), the family level (using parental education and occupation), and subjectively (World Health Organization Quality of Life measure).

Main Outcomes and Measures

Brain volume (85 parcels) and 5 whole-brain cortical morphology measures (gyrification index, thickness, sulcal depth, curvature, surface area) at term-equivalent age (median [range] age, 40 weeks, 5 days [36 weeks, 2 days to 45 weeks, 6 days] and 42 weeks [38 weeks, 2 days to 46 weeks, 1 day] for preterm and full-term infants, respectively).

Results

Participants were 170 extremely and very preterm infants (95 [55.9%] male; 4 of 166 [2.4%] Asian, 145 of 166 [87.3%] White) and 91 full-term or near-term infants (50 [54.9%] male; 3 of 86 [3.5%] Asian, 78 of 86 [90.7%] White infants) with median (range) birth GAs of 30 weeks, 0 days (22 weeks, 1 day, to 32 weeks, 6 days) and 39 weeks, 4 days (36 weeks, 3 days, to 42 weeks, 1 day), respectively. In fully adjusted models, birth GA was associated with a higher proportion of brain volumes (27 of 85 parcels [31.8%]; β range, -0.20 to 0.24) than neighborhood-level SES (1 of 85 parcels [1.2%]; β = 0.17 [95% CI, -0.16 to 0.50]) or family-level SES (maternal education: 4 of 85 parcels [4.7%]; β range, 0.09 to 0.15; maternal occupation: 1 of 85 parcels [1.2%]; β = 0.06 [95% CI, 0.02 to 0.11] respectively). There were interactions between GA and both family-level and subjective SES measures on regional brain volumes. Birth GA was associated with cortical surface area (β = 0.10 [95% CI, 0.02 to 0.18]) and gyrification index (β = 0.16 [95% CI, 0.07 to 0.25]); no SES measure was associated with cortical measures.

Conclusions and Relevance

In this cohort study of UK infants, birth GA and SES were associated with neonatal brain morphology, but low GA had more widely distributed associations with neonatal brain structure than SES. Further work is warranted to elucidate the mechanisms underlying the association of both GA and SES with early brain development.

Methylation status of nc886 epiallele reflects periconceptional conditions and is associated with glucose metabolism through nc886 RNAs

BACKGROUND

Non-coding RNA 886 (nc886) is coded from a maternally inherited metastable epiallele. We set out to investigate the determinants and dynamics of the methylation pattern at the nc886 epiallele and how this methylation status associates with nc886 RNA expression. Furthermore, we investigated the associations between the nc886 methylation status or the levels of nc886 RNAs and metabolic traits in the YFS and KORA cohorts. The association between nc886 epiallele methylation and RNA expression was also validated in induced pluripotent stem cell (iPSC) lines.

RESULTS

We confirm that the methylation status of the nc886 epiallele is mostly binomial, with individuals displaying either a non- or hemi-methylated status, but we also describe intermediately and close to fully methylated individuals. We show that an individual's methylation status is associated with the mother's age and socioeconomic status, but not with the individual's own genetics. Once established, the methylation status of the nc886 epiallele remains stable for at least 25 years. This methylation status is strongly associated with the levels of nc886 non-coding RNAs in serum, blood, and iPSC lines. In addition, nc886 methylation status associates with glucose and insulin levels during adolescence but not with the indicators of glucose metabolism or the incidence of type 2 diabetes in adulthood. However, the nc886-3p RNA levels also associate with glucose metabolism in adulthood.

CONCLUSIONS

These results indicate that nc886 metastable epiallele methylation is tuned by the periconceptional conditions and it associates with glucose metabolism through the expression of the ncRNAs coded in the epiallele region.

Methylation status of nc886 epiallele reflects periconceptional conditions and is associated with glucose metabolism through nc886 RNAs

BACKGROUND

Non-coding RNA 886 (nc886) is coded from a maternally inherited metastable epiallele. We set out to investigate the determinants and dynamics of the methylation pattern at the nc886 epiallele and how this methylation status associates with nc886 RNA expression. Furthermore, we investigated the associations between the nc886 methylation status or the levels of nc886 RNAs and metabolic traits in the YFS and KORA cohorts. The association between nc886 epiallele methylation and RNA expression was also validated in induced pluripotent stem cell (iPSC) lines.

RESULTS

We confirm that the methylation status of the nc886 epiallele is mostly binomial, with individuals displaying either a non- or hemi-methylated status, but we also describe intermediately and close to fully methylated individuals. We show that an individual's methylation status is associated with the mother's age and socioeconomic status, but not with the individual's own genetics. Once established, the methylation status of the nc886 epiallele remains stable for at least 25 years. This methylation status is strongly associated with the levels of nc886 non-coding RNAs in serum, blood, and iPSC lines. In addition, nc886 methylation status associates with glucose and insulin levels during adolescence but not with the indicators of glucose metabolism or the incidence of type 2 diabetes in adulthood. However, the nc886-3p RNA levels also associate with glucose metabolism in adulthood.

CONCLUSIONS

These results indicate that nc886 metastable epiallele methylation is tuned by the periconceptional conditions and it associates with glucose metabolism through the expression of the ncRNAs coded in the epiallele region.