Years of education mediate the association between adverse childhood experiences and unintended pregnancy: A population-based study in Japan.

BACKGROUND: Adverse childhood experiences (ACEs) have been associated with unintended pregnancies, including mistimed pregnancies (MP) and unwanted pregnancies (UWP). However, it remains unknown which cluster of ACEs (i.e., child maltreatment/household dysfunction and deprivation/threat) are associated with MP/UWP and whether years of education mediate these associations. OBJECTIVE: To investigate the association of the clusters of ACEs with MP and UWP, while also examining the mediating effect of education years. PARTICIPANTS AND SETTING: A retrospective cohort study among 7652 postpartum women in Chiba, Japan. METHODS: MP/UWP was defined by emotional responses to confirming pregnancy. Multinomial logistic regression analyses with multiple imputed datasets estimated the relative risk ratio (RRR) of MP/UWP by cumulative scores and each cluster of ACEs. Causal mediation analysis assessed the indirect effects of years of education. RESULTS: Women with 4 or more ACEs were at a 2.4 times higher risk of MP (95 % confidence interval (CI): 1.6-3.8) and a 5.0 times higher risk of UWP (95 % CI: 3.1-8.2). Among ACE clusters, having 3 or more household dysfunction showed the strongest association with MP (RRR: 1.91, 95 % CI: 1.23-2.95), and having 3 or more deprivation showed the strongest association with UWP (RRR: 3.69, 95 % CI: 2.00-6.83). Education years mediated 16 % and 11 % of the association between total ACEs and MP/UWP, respectively, with a similar trend observed in each cluster. CONCLUSIONS: Not only ACEs score but also each cluster of ACEs was associated with MP and UWP. The mediating effects of years of education were modest.

Association between maternal dissatisfaction with oneself at birth and shaking and smothering toward the offspring up to 18 months old.

BACKGROUND: A mother who feels dissatisfaction with herself may resort to abusive behavior such as shaking or smothering toward their offspring. Understanding this association can inform effective prevention strategies. OBJECTIVE: This study aimed to investigate the associations between maternal feelings of dissatisfaction with oneself and infant physical abuse. PARTICIPANTS AND SETTING: The study included 434 mothers who had recently given birth in two obstetric wards in a relatively wealthy area in Tokyo, Japan. METHODS: Adopting a longitudinal design, the study used questionnaires post-childbirth to measure mothers' dissatisfaction with themselves. This involved evaluating perceptions of failing to meet personal standards or self-image. Physical abuse (specifically shaking or smothering) in infants was tracked at 3, 6, 12, and 18 months. Data analysis comprised multilevel analysis, group-based trajectory modeling, and multivariable logistic regression to explore the association between maternal dissatisfaction and child physical abuse. RESULTS: Multilevel analysis showed that mothers with middle or high dissatisfaction with themselves were more likely to abuse their infant compared to mothers with low dissatisfaction with themselves (adjusted odds ratios [aOR] 5.71, 95 % confidence interval [CI], 1.06-30.78 and aOR 12.47, 95 % CI: 2.11-73.69, respectively). Trajectory analyses indicated that mothers with middle or high dissatisfaction with themselves were consistently more likely to abuse their infants up to 18 months (aOR 8.08, 95 % CI 1.61-40.53 and aOR 6.42, 95 % CI 1.27-32.43, respectively). CONCLUSIONS: Our findings highlight a robust association between mother's dissatisfaction with themselves and a higher risk of infant physical abuse. These insights call for a comprehensive review of preventive measures for childhood physical abuse.

Home visitors' needs and perceptions of the benefits of a home visiting program for childcare support in Japan: A qualitative study of home visitors.

BACKGROUND: The Home Visiting Program for Childcare Support (HV-CCS; "Yoiku Shien Homon Jigyo" in Japanese) has targeted families in need of parenting support and those at risk of child maltreatment in Japan. OBJECTIVE: The aim of this study was to explore the needs and perceptions of benefits of home visitors in HV-CCS. PARTICIPANTS AND SETTING: Sixteen home visitors agreed to participate in the interview. METHODS: This study conducted 1-hour semi-structured interviews with 16 home visitors and analyzed approximately 18 h of interview data using thematic analysis. RESULTS: The findings suggested that home visitors required training to enhance individual skills and knowledge about mental health of caregivers or children. Additionally, they required environmental support, particularly for transportation expenses and parking places. Multidisciplinary communicative support is also necessary, as well as system to improve the process of support. Home visitor perceived the HV-CCS as beneficial in preventing child maltreatment by improving parenting skills and home environment, providing psychological support for mothers, and entering families' intimate spaces. CONCLUSIONS: To ensure the continuity and improvement of home visits for parents and children in Japan, it is essential to address the identified needs of home visitors.

Association between gestational weight gain and behavioral problems of the offspring aged 6-7 years: A population-based study in Japan.

OBJECTIVE: To identify the optimal gestational weight gain (GWG) thresholds for behavioral problems and prosocial behavior in 6- to 7-year-old children. METHODS: A retrospective cohort study was conducted using data from the Adachi Child Health Impact of Living Difficulty study, including all first-graders in public schools in Adachi, Tokyo, in 2017, 2019, and 2021 (n = 11 048, response rate = 80.1%). GWG was based on clinical records in the Mother and Child Health Handbook. Total difficulties and prosocial behavior were assessed using the Strength and Difficulties Questionnaire. Logistic regression models with restricted cubic splines, and quintile categories were employed to examine the association of GWG with the clinical range of total difficulties and prosocial behavior, controlling for covariates. RESULTS: The association between GWG and total difficulties exhibited a reverse J-shaped pattern, with low GWG, but not high GWG, increasing the risk (odds ratio [OR] 1.20, 95% confidence interval [CI] 1.01-1.42, P = 0.039 for GWG < 7 kg; OR 1.03, 95% CI 0.85-1.24, P = 0.786 for GWG > 14 kg), referencing the median (10 kg). High GWG was associated with a lower risk of problems in prosocial behavior (OR = 0.77, 95% CI 0.62-0.95, P = 0.017 for GWG > 14 kg; OR 1.06, 95% CI 0.88-1.27, P = 0.532 for GWG <7 kg). CONCLUSION: GWG less than 7 kg may increase the risk of total difficulties, whereas GWG over 14 kg may serve as a protective factor for prosocial behavior in 6- to 7-year-old children.

Association between Short Stature at Grade 1 and Permanent Teeth Caries at Grade 6 in Elementary School Children in Japan: A Population-Based Cohort Study.

Short stature in children is a marker of low nutritional status and has been suggested to be associated with dental caries. However, longitudinal studies on this topic are scarce. Data from a longitudinal study of elementary school children in Adachi City, Tokyo, Japan, were analyzed. In 2015, caregivers of children at grade 1 answered questionnaires, and information on dental caries and height measured at school health checkups was merged and followed to grade 6 (N = 3576; follow up rate = 83.3%). The association between short stature at grade 1 (-2.01 standard deviation (SD)--3.00 SD, or <-3.00 SD in height-for-age according to the World Health Organization criteria) and the number of decayed, missing, or filled permanent teeth (DMFT) at grade 6 was examined using multivariable Poisson regression with robust standard error. After adjusting for confounders, children with a short stature at grade 1 had a higher DMFT number at grade 6: the mean ratios (95% confidence interval) were 1.17 (0.89-1.54) and 2.18 (1.03-4.64) for children with a height-for-age -2.01 SD--3.00 SD, and those with a height-for-age < -3.00, respectively. Short stature at grade 1 could be a marker of future dental caries in the permanent teeth at grade 6.

Association of maternal pre-pregnancy body mass index with resilience and prosociality of the offspring aged 6-7 years old: a population-based cohort study in Japan.

The association between maternal pre-pregnancy obesity and child behavior problems has been widely researched, leaving a gap in understanding the positive aspects of children's mental health. The present study aimed to investigate the association between maternal pre-pregnancy body mass index (BMI) and resilience and prosociality among 6-7 year-old children in Japan. A retrospective cohort study was conducted using data from the Adachi Child Health Impact of Living Difficulty (A-CHILD) study, a population-based study in 2017 and 2019 including all first-grade students in public schools in Adachi, Tokyo, Japan (n = 7328, response rate = 84.7%). Resilience and prosociality were measured by the Children's Resilient Coping Scale and the Strength and Difficulties Questionnaire, respectively. Maternal pre-pregnancy weight and height were reported based on the Mother and Child Health Handbook, and BMI was categorized as underweight (BMI < 18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25.0-29.9), and obesity (BMI ≥ 30). Linear regression models were employed to control for covariates. Maternal pre-pregnancy obesity was found to be negatively associated with child resilience (coefficient: - 3.29; 95% CI - 6.42--0.15), while maternal underweight was negatively associated with child prosociality (coefficient: - 0.12; 95% CI - 0.24--0.005) compared to mothers of pre-pregnancy normal BMI. Perinatal factors, such as gestational weight gain, gestational age, and birth weight, did not mediate the association. Our findings suggest that maternal pre-pregnancy obesity is linked to decreased resilience and maternal underweight is linked to decreased prosociality in children aged 6-7 years. Maintaining an appropriate BMI range before pregnancy may be crucial for enhancing resilience and prosociality of offspring.

The effect of breathing relaxation to improve poor sleep quality in adults using a huggable human-shaped device: a randomized controlled trial.

PURPOSE: To examine whether or not breathing relaxation, using a huggable human-shaped device, improves poor sleep quality in adults. METHODS: We conducted a randomized controlled trial using outpatients with sleep problems from two clinics in Japan. The intervention group conducted three minutes of breathing relaxation using a huggable human-shaped device before going to bed every night for four weeks. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), at pre-intervention, mid-intervention (2 weeks after pre-intervention), and post-intervention (4 weeks after pre-intervention). We employed intention-to-treat analysis. RESULTS: A total of 68 participants (mean [SD] age, 41.7 [11.4] years; 64 female [95%]) were randomly assigned to the intervention group (n = 29, mean [SD] age, 43.6 [9.5] years; 28 female [97%]) and the control group (n = 36, mean [SD] age, 40.3 [12.7] years; 36 female [95%]). The intervention group showed a significant decrease in the PSQI score compared to the control group (F = 3.81, p = 0.025, effect size (η2) = 0.057). Furthermore, we found the intervention to be more effective in participants without suicide risk and with a lower number of adverse childhood experiences (effect size (η2) = 0.080 and 0.160, respectively). CONCLUSIONS: A novel psychological intervention, breathing relaxation using a huggable human-shaped device, may be effective to improve sleep quality among people with sleep problems, especially those without severe psychological symptoms. TRIAL REGISTRATION: UMIN000045262. (Registration Date: September 28th, 2021).

Association between the number of convenience stores and caries status in permanent teeth among elementary school children: results from the A-CHILD population-based longitudinal cohort study.

Background: In Japan, people have rich access to 24-h convenience stores where they can buy sweets, juice and fluoride hygiene products, among others. However, the association between the number of convenience stores in a neighbourhood and caries in elementary school children status has not been studied. This study aimed to investigate this particular association. Methods: Data were derived from a population-based longitudinal cohort study (A-CHILD study) of elementary school children from first-grade to fourth-grade in Adachi City, Tokyo. Caregivers were asked to complete a questionnaire in 2015, 2016, and 2018. A total of 3,136 caregivers provided a valid response. We analysed the association using multilevel Poisson regression. Results: The mean number of caries among children in school districts with low, middle, and high number of convenience stores was 0.31 (SD: 0.81), 0.21 (SD: 0.69), and 0.16 (SD: 0.58). After covariate adjustment, children in the school districts with high and middle number of convenience stores had 44% (mean ratio 0.56, 95% CI: 0.31, 0.998) and 31% (mean ratio 0.69, 95% CI: 0.42, 1.13) fewer caries in their permanent teeth, respectively, than children in the school districts with low number of convenience stores. We also found dose-response relationship (p for trend: 0.042). Conclusion: Higher number of convenience stores in a school district was associated with fewer caries in permanent teeth among elementary school children. Further study elucidating the mechanism on this protective association is warranted.

Persistent poverty and child dental caries: time-varying exposure analysis.

BACKGROUND: This study investigated the cumulative impact of persistent poverty on dental caries among elementary schoolchildren in Japan. METHODS: Data were derived from four-wave longitudinal data of children in all public elementary schools in Adachi City, Tokyo, Japan, from 2015 to 2020 (n=4291, response rate: 80.1%-83.8%). Poverty status, defined as annual household income

Association between poor parent-daughter relationships and the risk of hyperglycemia in pregnancy: a hospital-based prospective cohort study in Japan.

BACKGROUND: Adverse child experiences (ACEs), childhood maltreatment and household dysfunction, are risk factors of hyperglycemia in pregnancy (HIP), including diabetes before pregnancy, gestational diabetes (GDM), and overt diabetes in pregnancy, through increased risk of unhealthy behaviors, obesity, and stress response system dysfunction. While ACEs are often difficult to be assessed in hospital settings, parent-daughter relationship, that is, pregnant women's relationship with their parents can be considered as a measurable maker for ACEs that may be associated with HIP. The purpose of this study is to examine the association between poor parent-daughter relationship and HIP. METHODS: Hospital-based prospective cohort study was conducted in Japan (N = 6,264). Women visiting participating 58 facilities for delivery between April 2019 and March 2020 were included. Parent-daughter relationship was assessed by a questionnaire asking whether participants were satisfied with their relationship with their parents. HIP was diagnosed based on the criteria used in Japan. A multiple logistic regression model was applied to adjust for covariates. RESULTS: Pregnant women who were not very satisfied and not satisfied at all with the relationship with their parents, and HIP were 343 (5.5%), 74 (1.2%), and 274 (4.4%), respectively. Pregnant women who were not very satisfied with their parent-daughter relationship showed a significant positive association with HIP in the crude model (odds ratio (OR): 1.71, 95% confidence interval (CI): 1.11-2.63). When stratified by psychiatric disease history, we found a significant positive association among those without psychiatric disease history (OR: 1.77, 95% CI: 1.11-2.84), but not among those with psychiatric disease history (OR: 0.61, 95% CI: 0.16-2.28). CONCLUSIONS: Poor parent-daughter relationship was associated with the risk of HIP among pregnant women without psychiatric disease history, suggesting that this simple question could be used to estimate the risk of HIP when it was challenging to inquire directly about ACEs. Further research is needed to elucidate the mechanism of the association.

Association between skipping breakfast and prediabetes among adolescence in Japan: Results from A-CHILD study.

Objective: Adolescents with prediabetes are at high risk of developing type 2 diabetes in later life. It is necessary to identify risk factors for prediabetes in adolescents. This study aimed to examine the association between skipping breakfast and prediabetes among adolescents in Japan. Study design: We used the population-based cross-sectional data of eighth grade in junior high school students from the Adachi Child Health Impact of Living Difficulty (A-CHILD) study conducted in Adachi City, Tokyo, Japan, in 2016, 2018, and 2020. Skipping breakfast was assessed using self-reported questionnaires (N=1510). Prediabetes was defined as hemoglobin A1c (HbA1c) levels of 5.6-6.4%. The association between skipping breakfast and prediabetes was evaluated using multivariate logistic regression analysis. Stratified analysis was also performed using BMI, 1 SD or more, or less than 1SD, as overweight was defined as 1SD or more. Results: Students who skipped breakfast were 16.4% (n=248). The prevalence of prediabetes was 3.8% (n=58). Skipping breakfast exhibited a significant association with prediabetes (OR:1.95, 95% CI: 1.03 to 3.69) after adjusting for sex, annual household income, family history of diabetes mellitus, BMI, and survey year. Stratified analysis showed stronger association among students with overweight (BMI ≥1SD) (OR=4.31, 95% CI 1.06-17.58), while non-sigificant among students without overweight (BMI<1SD) (OR=1.62, 95% CI 0.76-3.47). Conclusions: Skipping breakfast in Japanese adolescents, especially those with overweight, was associated with prediabetes. The promotion of avoiding skipping breakfast may help to prevent prediabetes.

Food Categories for Breakfast and Mental Health among Children in Japan: Results from the A-CHILD Study.

There is limited evidence that what children eat for breakfast contributes to their mental health. This study aimed to examine the associations between food categories for breakfast and mental health among children in Japan. A proportion of participants aged 9-10 years in the Adachi Child Health Impact of Living Difficulty (A-CHILD) study in Japan who consumed breakfast daily were included (n = 281). Foods eaten for breakfast were reported by the children each morning for 7 consecutive days, and defined according to the food categories in the Japanese Food Guide Spinning Top. Child mental health was assessed by caregivers using the Strength and Difficulties Questionnaire. The mean intake frequencies per week were six times for grain dishes, two times for milk products, and one time for fruits. Linear regression analysis revealed an inverse association between the frequent intake of grain dishes, whether rice or bread, and problem behaviors after adjustment for potential confounders. However, confectionaries, which mainly consisted of sweet breads or pastries, were not associated with problem behaviors. The intake of non-sweet grain dishes at breakfast may be effective for preventing behavioral problems in children.

"What Did You Do in the War, Daddy?": Paternal Military Conscription During WWII, Economic Hardship and Family Violence in Childhood, and Health in Late Life in Japan.

Childhood adversity is a risk factor for poor health in late life and includes economic hardship and family violence, whose prevalence is high among offspring of military conscripted father. We assessed the association between paternal military conscription (PMC) and paternal war death (PWD) during Second World War and self-rated health (SRH) among older adults in Japan. Data were obtained from a population-based cohort of functionally independent people aged 65 years or older from 39 municipalities across Japan in 2016. Information on PMC and SRH was obtained through a self-report questionnaire. A total of 20,286 participants were analyzed with multivariate logistic regression to investigate the association between PMC, PWD, and poor health. Causal mediation analysis was performed to see whether childhood economic hardship and family violence mediated the association. Among participants, 19.7% reported PMC (including 3.3% PWD). In the age- and sex-adjusted model, older people with PMC showed higher risk of poor health (odds ratio [OR]: 1.16, 95% confidence interval [CI] [1.06, 1.28]), while those with PWD were not associated (OR: 0.96, 95% CI [0.77, 1.20]). Causal mediation showed a mediation effect of childhood family violence exposure on the association between PMC and poor health (proportion mediated: 6.9%). Economic hardship did not mediate the association. PMC, but not PWD, increased the risk of poor health in older age, which was partially explained by the exposure to family violence in childhood. There appears to be a transgenerational health impact of war which continues to affect the health of offspring as they age.

Interventions to change parental parenting behaviour to reduce unintentional childhood injury: a randomised controlled trial.

OBJECTIVE: The previous study has shown the impact of paternal involvement in childcare on unintentional childhood injury; yet the causality is unknown. The purpose of this study is to investigate whether the intervention of an educational video on paternal involvement in childcare can prevent unintentional injury among young children. METHODS: A randomised controlled trial of parents of children born at two obstetrics wards in Japan (n=451, intervention group: 223, control group: 228) was conducted. Parents in the intervention group watched an educational video that promote paternal involvement in childcare, while parents in the control group watched an educational video on the prevention of shaken baby syndrome. The participants were followed for up to 18 months after the birth of their child. The primary outcome of this study was unintentional injury at 3, 6, 12 and 18 months. The secondary outcome was paternal involvement in childcare based on maternal observation. Unintentional injury-free rates over time were assessed using the Cox proportional hazard model. RESULTS: Children in the intervention group were less likely to have unintentional injury, such as burn (HR: 0.29 (95% CI: 0.09 to 0.87)) and caught by a door (HR: 0.66 (95% CI: 0.48 to 0.91)) compared with the control group. Fathers in the intervention group showed higher frequency of taking their children for a walk (coefficient: 0.19 (95% CI: 0.05 to 0.32)). CONCLUSIONS: Educational videos promoting paternal involvement in childcare is effective to prevent unintentional childhood injury.

Detecting Intimate Partner Violence During Pregnancy Using Municipal Pregnancy Registration Records: An Administrative Data Analysis.

Intimate partner violence (IPV) during pregnancy needs to be prevented because it leads to negative health outcomes for both the mother and offspring. However, it is not easy to detect women who suffer from IPV by health practitioners or public health staff due to stigma attached to it or hesitation of the women to disclose it. The aim of this study is to develop a scale using pregnancy registration records to detect IPV during pregnancy. We used administrative data of pregnancy registration records of Adachi City, Tokyo, in the 2016 fiscal year (N = 5,990). IPV was assessed at the first interview or another opportunity for further assessment by a public health nurse. The data include registration information, demographics, health and perinatal status, and social environment. Multiple logistic regression model was used to predict IPV. IPV cases were found for 24 (0.4%) cases. Subsequent child (odds ratio [OR]: 3.45, 95% confidence interval [CI] [1.02-11.6]), single marital status (OR: 7.96, 95% CI [2.88-22.2]), thinness (OR: 3.17, 95% CI [1.13-8.90]), past pregnancy of four or more times (OR: 5.25, 95% CI [1.35-20.4]), having trouble with family member (OR: 5.45, 95% CI [1.95, 15.2]), and poverty (OR: 6.27, 95% CI [2.25-17.5]) showed significant association with IPV. These variables detected IPV with good predictive power (area under receiver operating characteristic curve = 0.89, 95% CI [0.81-0.98]). We showed strong detectability of IPV during pregnancy using a scale based on pregnancy registration records in which IPV was not asked directly. The current study is useful to detect IPV during pregnancy and prevent further adverse health outcomes due to IPV during pregnancy.

School- and community-level protective factors for resilience among chronically maltreated children in Japan.

PURPOSE: Few studies have investigated how school- and community-level modifiable factors might enhance resilience, defined as an ability to recover from and cope with adversity, among chronically maltreated pre-adolescent children. This study aims to investigate school and community factors that can increase children's resilience following maltreatment. METHODS: We used data from the Adachi child health impact of living difficulty (A-CHILD) Study, a population-based prospective longitudinal study starting with first-grade children in all public elementary schools in Adachi City, Tokyo, Japan in 2015. Children who experienced chronic maltreatment while in 1st and 4th grades and whose resilience scores were available at those grades were included in the analysis (N = 789). Crude and multiple regressions were used to examine associations of child-reported school factors (i.e., school social capital, number of friends to consult with) and community factors (i.e., having a non-parental role model and supportive adult, having a third place, which is defined as a place other than home to spend time after school) with parent-reported resilience at 4th grade. These regressions were also performed stratified by sex. RESULTS: School social capital and having a non-parental role model at 4th grade were positively associated with resilience after adjusting covariates, including resilience at 1st grade [coefficient = 3.63, 95% confidence intervals (CI) 2.26-4.99; coefficient = 2.52, 95% CI 0.57-4.38, respectively]. Analysis by sex revealed that having a supportive adult, but not a role model, was associated with resilience among girls (coefficient = 5.50, 95% CI 0.20-10.8). CONCLUSIONS: The findings suggest that school and community factors can promote resilience following child maltreatment, and these factors are different between boys and girls.

Being Left Alone at Home and Dental Caries of Children Aged 6-7 Years.

BACKGROUND: Leaving children alone at home is considered child neglect in some countries but is not prohibited in Japan. We investigated the association between being left alone at home and dental caries of children aged 6-7 years in Japan. METHODS: The data on first graders in all 69 public elementary schools in Adachi, Tokyo, obtained from repeated cross-sectional surveys in 2015, 2017, and 2019 were analyzed. Caregivers answered the questionnaire, and the data were linked to the information on children's dental caries evaluated in school dental health checkups (N = 12,029). Poisson regression analysis with propensity score matching (PSM) was applied to account for confounders. RESULTS: Leaving children alone at home for ≥1 hour during the weekdays was reported by 46.4% of the caregivers, which did not vary across years. The PSM analysis showed that, compared with children never being left alone at home, children being left alone at home for ≥1 time per week had more dental caries (mean ratio [MR] 1.11; 95% confidence interval (CI), 1.02-1.21; P = 0.016), while <1 time per week was not associated (MR 0.97; 95% CI, 0.92-1.03; P = 0.345). The difference between those being left alone at home for <1 time per week and those being left alone for ≥1 time per week was not significant after applying Bonferroni correction (MR 1.12; 95% CI, 1.00-1.26; P = 0.041). CONCLUSION: Leaving children alone at home for ≥1 hour every week might be a risk factor for dental caries of children aged 6-7 years.

Number of Siblings and Social Capital Among Parents Rearing Schoolchildren: Results From the A-CHILD Study.

BACKGROUND: Having siblings may foster sociality; however, little is known about whether sibling number determines social capital, the resources obtained through social networks. We examined the association between sibling number and social capital among Japanese parents rearing schoolchildren. METHODS: We used cross-sectional data from the 2018 and 2019 Adachi Child Health Impact of Living Difficulty (A-CHILD) study, targeting all primary and junior high school students and their parents in Adachi, Tokyo, Japan (n = 8,082). Individual-level social capital was evaluated by assessing caregivers' social cohesion, social support, and group affiliation. All analyses were adjusted for age and sex. RESULTS: An inverse U-shaped association was found between sibling number and social capital. Adults who grew up with one or two, but not three or more siblings had greater social support (coefficient = 0.23; 95% confidence interval [CI], 0.06-0.40 and coefficient = 0.46; 95% CI, 0.29-0.64, respectively) than those who grew up as an only child, after covariate adjustment. Adults who grew up with two or three, but not one or four or more siblings had greater group affiliation (coefficient = 0.09; 95% CI, 0.03-0.16 and coefficient = 0.09; 95% CI, 0.01-0.18, respectively) than those who grew up as an only child, after covariate adjustment. Sibling number was not associated with social cohesion. CONCLUSION: Growing up with one to three siblings was associated with higher social capital in adulthood than being an only child. Having siblings may provide an opportunity to foster social capital.

Impact of exposure to secondhand smoke on the risk of obesity in early adolescence.

BACKGROUND: Exposure to secondhand smoke (SHS) might be associated with obesity in children. This study aimed to evaluate whether continuous, quit, or start exposure to SHS was associated with obesity risk in early adolescents. METHODS: We used population-based longitudinal data of primary school students in Adachi City, Tokyo, Japan, in 2018 (4th grade) and 2020 (6th grade) and studied 3605 students. The association between continuous, quit, start, or never exposed to SHS from 4th to 6th grade and BMI categories (underweight or normal weight, overweight, obesity) in 6th grade was investigated using ordinal logistic regression models. RESULTS: Continuous SHS group showed a higher risk of being in the high BMI category than no SHS group (OR = 1.51, 95% CI 1.16-1.96). The stratified analyses by sex showed a similar association in boys (OR = 1.74, 95% CI 1.25-2.44) but not in girls (OR = 1.14, 95% CI 0.74-1.76). Quitting SHS group did not show a higher risk of being in the high BMI category than no SHS group (OR = 1.11, 95% CI 0.75-1.66) and the same was true for boys (OR 1.46, 95% CI 0.88-2.41). CONCLUSIONS: Continuous SHS was a risk factor for obesity in boys in early adolescence; however, quitting SHS may help prevent it. IMPACT: Continuous secondhand smoke (SHS) was not associated with a higher risk of obesity in early adolescence in girls. Continuous SHS can be a risk factor for obesity in early adolescence in boys. Quitting SHS may help to prevent obesity in early adolescence in boys.

Impacts of the COVID-19 Pandemic Exposure on Child Dental Caries: Difference-in-Differences Analysis.

The impact of the coronavirus disease 2019 (COVID-19) pandemic on dental caries is unknown. We investigated the effect of the pandemic on child dental caries in Japan by comparing the increase in dental caries from fourth to sixth grade between two cohorts, COVID-19 exposed cohort and COVID-19 unexposed cohort, using difference-in-differences analysis. Longitudinal data that followed elementary school children in Adachi City, Tokyo, were analyzed. The analysis consisted of two cohorts: those who were in fourth grade in 2016 and sixth grade in 2018 (COVID-19 unexposed cohort, N = 399) and those who were in fourth grade in 2018 and sixth grade in 2020 (COVID-19 exposed cohort, N = 3,082). Children's dental caries were examined by school dentists. A difference-in-differences analysis, adjusting for time-variant variables, i.e., household socioeconomic status, children's oral health behavior, and caregivers' psychological distress, was performed. In fourth grade, the number of Decayed, Missing, and Filled permanent Teeth (DMFT) was not different between the COVID-19 unexposed and exposed cohorts (mean = 0.241 and 0.242, respectively). In sixth grade, DMFT increased by 0.067 in the COVID-19 unexposed cohort and 0.180 in the COVID-19 exposed cohort. The interaction term of grade and cohorts for caries by difference-in-differences analysis showed that dental caries among the COVID-19 exposed cohort showed a significant increase in the number of dental caries by 0.116 (95% confidence interval 0.015, 0.216) compared to the COVID-19 unexposed cohort. Child dental caries slightly increased after the pandemic. Studies with longer follow-ups are needed to evaluate the impact of the pandemic on child dental caries.