Purpose: Epidemiological studies have reported that environmental factors from fetal period to early childhood can influence the risk of non-communicable diseases in adulthood. This concept has been termed the developmental origins of health and disease (DOHaD). The Chiba study of Mother and Child Health (C-MACH) is a DOHaD concept-based birth cohort study which started in 2014. This study aims to investigate the effects of genetic and environmental factors, particularly fetal and postnatal living environment, on children’s health. We also aim to identify candidate biomarkers for their health status. Moreover, the second phase study of C-MACH which was initiated in 2021 aimed at expanding the sample size, especially for gut microbiota and epigenomic analysis; it also aimed at clarifying the impact of the coronavirus disease 2019 (COVID-19) pandemic on children’s health. Participants: This study consists of four hospital-based cohorts. Women who were <13 weeks pregnant and their partners were enrolled in the study. All data and biological samples will be stored in the Chiba University Centre for Preventive Medical Sciences. Findings to date: A total of 561 women and their partners provided their consent to participate in this study. Of these women, 505 completed the questionnaire during the early gestational period. The mean age of the 505 women at enrolment was 33.0 (SD, 4.5) years. The mean prepregnancy body mass index (BMI) was 21.7 (SD, 3.6) kg/m², with 74.5% of the women having a BMI of 18.5–24.9 kg/m². About 5.2% of the women smoked cigarettes during the early stages of pregnancy. Future plans: The primary study outcomes are allergies, obesity, endocrine and metabolic disorders and developmental difficulties in children. Variables related to genome, metabolome, epigenome, gut microbiota and exposome will be evaluated as health-related factors. The relationships between these outcomes and the health-related factors will be analysed.

Objective: Community-based integrated care wards (CICW) play a role in supporting the return of patients to their homes. However, studies investigating the readmission risk associated with CICW are lacking. To investigate the influence of CICW on readmission, we conducted a retrospective cohort study among Japanese elderly people.Materials and Methods: This study used data from the Diagnosis Procedure Combination (DPC) and medical records of the Hamada Medical Center, Shimane Prefecture in 2014–2019. The number of subjects and readmission in each hospitalization case (general ward only [GW] and CICW) were 1,521 and 416 subjects and 152 and 49 cases, respectively. We selected the hospitalization cases for heart failure (I30–I52), ischemic heart disease (I20–I25), pneumonia (J09–J18), chronic lower respiratory tract diseases (J40–J47), intestinal diseases (K55–K64), cerebrovascular disease (I60–I69), gallbladder, bile duct, and pancreatic diseases (K80–K87) from the International Statistical Classification of Diseases and Related Health Problems (ICD-10). The hazard ratios (HRs) and 95% confidence intervals (CIs) for readmission via a CICW were estimated using a multivariate Cox proportional hazards model.Results: The HRs for readmission associated with CICW were not different between the shorter and longer durations, considering the percentage of CICW stay. Compared with GW cases, the HR of CICW cases was 0.40 (95% CI, 0.17–0.92) in coordination with outside agencies of hospital discharge support. While the HR of GW cases was 2.35 (95% CI 1.01–5.47), a significantly increased risk was observed in people living alone. A similar risk was not observed in CICW cases with the HR of 0.56 (95% CI 0.15–2.07).Conclusion: The present study observed decreased risk of readmission among the patients discharged from CICW, compared to GW. Further research is required to clarify the causal factors for this decreased risk.

Previous studies have shown that more frequent social participation was associated with a reduced risk of mortality. However, limited studies have explored the changes in the frequency of social participation in older adults. We investigated the impact of the changes in the frequency of social participation on all-cause mortality in Japanese older adults aged 60 years and older. The current study, conducted as a secondary analysis, was a retrospective cohort study using open available data. The participants were 2240 older adults (45.4% male and 54.6% female) sampled nationwide from Japan who responded to the interview survey. Changes in the frequency of social participation were categorized into four groups (none, initiated, decreased, and continued pattern) based on the responses in the baseline and last surveys. The Cox proportional-hazards model showed a decreased risk of all-cause mortality in decreased and continued patterns of social participation. Stratified analysis by sex showed a decreased risk of mortality in the continued pattern only among males. The results of the current study suggest that the initiation of social participation at an earlier phase of life transition, such as retirement, may be beneficial for individuals.

Drastic changes such as school closures and stay-at-home measures due to the global COVID-19 pandemic, may have long-term negative effects on children's mental health; however, longitudinal studies after 2021 are limited. This study aimed to observe the long-term effects of the COVID-19 pandemic on children's mental health by exploring changes in their mental health over a period of 18 months. We conducted a longitudinal study at Chiba Prefecture in Japan, focusing on schoolchildren's mental health changes. Data were obtained from the Strengths and Difficulties Questionnaire (SDQ) questionnaire conducted at single primary school three times from October 2021 to March 2023 which and included 183 participants. This study adopted a linear-mixed model to evaluate changes in children's SDQ scores, with sex and grade as the independent variables, and participants as a random effect. Regarding changes in SDQ scores, there were no significant changes in the total difficulty scores or in each subscale; Emotional Symptoms, Conduct Problems, Hyperactivity/Inattention, Peer Problems, and Prosocial Behavior. There was no statistically significant interaction between changes in SDQ scores and sex. This report indicates that the impact of the COVID-19 pandemic on the mental health of Japanese primary schoolchildren was negligible in the later phase of the pandemic. However, the impact may differ from country to country owing to factors such as social restrictions during the COVID-19 pandemic.