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Background: In regions with a high prevalence of peanut allergy (PA), there is a consensus that the introduction of peanuts in early infancy is preventive against the development of PA. However, few studies have investigated whether the introduction of peanuts to infants is associated with PA in regions with a low prevalence of PA, including Japan. Methods: We used data from 74,240 mother–child pairs who participated in the Japan Environment and Children’s Study, a prospective birth cohort recruited between January 2011 and March 2014. A logistic regression model was used to analyze the association between infantile peanut introduction and PA at the age of 4 years with non-infantile peanut introduction as the reference group, adjusted for potential confounders. Results: The percentage of infantile peanut introduction was 4.9% (n = 3,294), and 286 (0.4%) participants had allergic symptoms to peanuts at 4 years of age. Of all participants, 129 (0.2%) had PA at 4 years of age, which was defined as allergic symptoms and sensitization to peanuts. Those with infantile peanut introduction had a lower prevalence of PA than those without infantile peanut introduction, although this did not reach statistical significance (adjusted odds ratio 0.53; 95% confidence interval, 0.17–1.68). Sensitivity analysis using IgE-mediated symptoms caused by peanuts as the outcome showed a similar result in relation to infantile peanut introduction. Conclusion: In countries with a low prevalence of PA, the effect of infantile peanut introduction on PA prevention was unclear.

Abstract Hypertensive disorders of pregnancy (HDP) increase the risk of preterm births and cesarean delivery. This study aimed to investigate whether maternal blood leukocyte, monocyte, or neutrophil counts in the first trimester are related to the development of HDP. Data were collected from the Japan Environment and Children’s Study, a large birth cohort study (n = 38,194) that recruited pregnant women in 15 Regional Centers across Japan (from January 2011 to March 2014). The odds ratios (ORs) for mild/severe HDP according to the cut-off value of leukocyte/neutrophil/monocyte counts by the receiver operating characteristic curve showed high ORs. Furthermore, pregnant women with the highest quartiles of leukocyte and monocyte counts had higher adjusted ORs (aORs) for mild (leukocyte: aOR = 1.27, 95% confidence interval [CI]: 1.02–1.58; monocyte: aOR = 1.30, 95% CI 1.04–1.63) and severe HDP (leukocyte: aOR = 1.51, 95% CI 1.08–2.13; monocyte: aOR = 1.44, 95% CI 1.03–2.01) compared with those with the lowest quartiles of those counts. In addition, pregnant women with the highest neutrophil counts had higher aOR for mild HDP (aOR = 1.26, 95% CI 1.02–1.56) compared with those with the lowest count. In conclusion, high leukocyte and monocyte counts in the first trimester are associated with the development of HDP. Thus, they may be used to predict subsequent HDP.

Background: The relationship between the season of birth, allergen sensitization, and allergic rhinitis have been inconsistent, and there are no studies that simultaneously consider vitamin D and allergen exposure. This study aimed to determine the associations between the season of birth, house dust mite (HDM) and Japanese cedar pollen (JCP) sensitization, and allergic rhinitis and pollinosis, while taking vitamin D levels and allergen exposure into account. Methods: This study included 4323 participants in the Sub-Cohort Study of the Japan Environment and Children's Study. A logistic regression model was used to analyze the association between the season of birth and sensitization to JCP or HDM (judged by specific immunoglobulin E) at age 2 and allergic rhinitis or pollinosis at age 3, adjusted for HDM or JCP exposure and vitamin D levels with potential confounders. Results: Participants born in spring or summer were more likely to have pollinosis than were those born in winter (adjusted odds ratio [aOR]: 2.08, 95% confidence interval [CI]: 1.13–3.82 for spring; aOR: 1.89, 95% CI: 1.03–3.47 for summer). Participants born in summer were more likely to have HDM sensitization than were those born in winter (Der p 1, aOR: 1.53, 95% CI: 1.10–2.15; Der f 1, aOR: 1.44, 95% CI: 1.03–2.01). Exposure to JCP and HDM were associated with pollinosis and HDM sensitization, respectively. Conclusions: Spring and summer births were associated with the development of pollinosis, and summer birth was associated with HDM sensitization, even when vitamin D and allergen exposure were considered. Further studies on mechanisms other than vitamin D and allergen exposure are required.

AimThis study aimed to determine whether excessive maternal weight gain during pregnancy was associated with a higher risk of prolonged labor.MethodsWe analyzed the data regarding maternal weight gain during pregnancy for the participants of Japan Environment and Children's Study (JECS), which is an ongoing nationwide prospective birth cohort study in Japan. After excluding participants with multiple pregnancies, with deliveries before 37 or beyond 42 weeks of gestation, or who had undergone cesarean section, 71,154 (nulliparous, n = 28,442) Japanese women were included. Prolonged labor was defined by a cutoff ranking at the 95th percentile and consequently defined as labor duration exceeding 12.7 h in multiparous women and exceeding 23.2 h in nulliparous women. These classifications were made according to labor curves established by the Japanese Society of Obstetrics and Gynecology Perinatal Committee developed in June 2021. Considering that no studies have conducted an investigation based on this new guideline, we analyzed the association between excessive maternal weight gain during pregnancy and prolonged labor by parity.ResultsThe overall incidence of prolonged labor was 10.2% (2,907/28,442) in nulliparous women and 6.1% (2,597/42,712) in multiparous women. Multivariable analysis indicated that excessive maternal weight gain was significantly associated with prolonged labor in nulliparous (adjusted odds ratio, 1.21; 95% confidence interval, 1.10-1.32) and multiparous women (adjusted odds ratio, 1.15; 95% confidence interval, 1.05-1.27). Kaplan-Meier survival analysis showed that as labor progressed, the percentage of women who had not yet delivered was higher among those with excessive maternal weight gain than among those with normal maternal weight gain in both the nulliparous (median labor duration 12.9 h vs 12.2 h, pConclusionExcessive maternal weight gain was significantly associated with prolonged labor in Japanese women.

The relationship between high body mass index (BMI) >25 kg/m2 and risk for stillbirth in the Japanese population remains unclear. This study aimed to estimate the impact of maternal obesity on the risk of stillbirth in a Japanese population. This prospective cohort study used data from the Japan Environment and Children’s Study, which recruited pregnant individuals between 2011 and 2014. A total of 93,772 fetuses were considered eligible for inclusion in this study. Stillbirth (fetal death before or during labor at ≥22 completed weeks of gestation) rates were compared among four pre-pregnancy BMI groups: underweight (

Abstract The association between maternal pre-pregnancy smoking status and asthma risk is unclear. This study aimed to investigate the association between pre- and post-pregnancy maternal smoking status and bronchial asthma at 3 years of age in a large birth cohort. Data of 75,411 mother–child pairs from the Japan Environment and Children's Study (JECS) were analysed using multivariate logistic regression analysis. Overall, 7.2% of the children had bronchial asthma. The maternal smoking status before childbirth was as follows: Never = 60.0%, Quit before recognising current pregnancy = 24.1%, Quit after finding out about current pregnancy = 12.3%, and Still smoking = 3.6%. Children of mothers who sustained smoking during pregnancy had an increased risk of bronchial asthma at 3 years of age even after adjusting for pre- and postnatal covariates (adjusted odds ratio [aOR] 1.34, 95% confidence interval [CI] 1.15–1.56). Children of mothers who quit before (aOR 1.09, 95% CI 1.02–1.18) or after (aOR 1.11, 95% CI 1.01–1.23) recognising the current pregnancy had an increased risk of bronchial asthma at 3 years of age. Maternal smoking throughout pregnancy and smoking exposure pre-pregnancy or in early pregnancy increases the risk of bronchial asthma in children.

BackgroundAnimal studies have shown that maternal low-fiber diets during pregnancy may impair brain development and function in offspring, but this has not been validated by epidemiological studies. The aim of this study was to investigate the link between maternal dietary fiber intake during pregnancy and neurodevelopmental delay in offspring using a large birth cohort.MethodsA total of 76,207 mother-infant pairs were analyzed using data from the Japan Environment and Children's Study, a nationwide prospective cohort study. Maternal dietary fiber intake was estimated using the food frequency questionnaire in mid-pregnancy. Maternal dietary fiber intake was adjusted for energy and classified into quintiles. Developmental delay was assessed in five domains using the Japanese version of the Ages and Stages Questionnaire, Third Edition at the age of 3 years. The logistic regression analysis was performed to estimate the odds ratio (OR) and 95% confidence interval (CI) for the link between dietary fiber intake during pregnancy and developmental delay at the age of 3 years.ResultsThe lowest intake group of total dietary fiber had a higher risk of delayed communication [adjusted OR (aOR), 1.51; 95% CI, 1.32–1.74], fine motor (aOR, 1.45; 95% CI, 1.32–1.61), problem-solving (aOR, 1.46; 95% CI, 1.32–1.61), and personal-social skills (aOR, 1.30; 95% CI, 1.12–1.50) than did the highest intake group. An analysis that excluded the effects of insufficient folic acid intake during pregnancy also showed a similar trend.ConclusionThis study showed that maternal dietary fiber deficiency during pregnancy might influence an increased risk of neurodevelopmental delay in offspring.

Abstract Gestational diabetes mellitus (GDM) is one of the most common pregnancy‐related complications; it is associated with adverse pregnancy outcomes and metabolic disorders in offspring, consistent with the concept of the developmental origins of health and disease. This cohort study of women without diabetes (n = 761), who were part of the Yamanashi Adjunct Study of the Japan Environment and Children’s Study, aimed to explore the associations between maternal GDM and their offspring’s level of high‐sensitivity C‐reactive protein (hsCRP), a biomarker of inflammatory and cardiovascular diseases. We analyzed the associations between GDM and the offspring’s hsCRP levels using a multiple logistic regression model. A mother with GDM significantly increased the risk for high hsCRP level by 4.07‐fold (≥2.0 mg/L) in the child. As such, maternal GDM was significantly associated with increased serum hsCRP levels in 8‐year‐old children.

Abstract Aims/Introduction Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy and is associated with adverse pregnancy outcomes. This study aimed to explore the associations between glycated hemoglobin (HbA1c) levels at the early stage of pregnancy and the GDM risk among non‐diabetic women in a nationwide study in Japan. In addition, the relationship between GDM and adverse pregnancy outcomes was also analyzed. Materials and Methods This cohort study (n = 89,799) used data from the Japan Environment and Children’s Study. We stratified the participants into four groups according to HbA1c levels at an early stage of pregnancy. We investigated the association of HbA1c at an early stage of pregnancy with the risk of GDM, and of GDM with the risk of some representative adverse pregnancy outcomes, using the multiple logistic regression model with adjustment for potential confounders. Results The adjusted odds ratio for GDM per 0.1 percentage point increase in HbA1c (%) was 1.20. The adjusted odds ratio for developing GDM was significantly increased in women from the HbA1c 5.0–5.4% category. GDM significantly increased the adjusted odds ratio for adverse pregnancy outcomes, such as hypertensive disorders of pregnancy, polyhydramnios and premature birth. Conclusions High‐normal HbA1c levels at the early stage of pregnancy are significantly associated with GDM risk in women in Japan. GDM was significantly associated with adverse pregnancy outcomes.

BackgroundThis study aimed to develop an efficient interview sheet during pregnancy and screening tool to identify pregnant women needing social support at obstetric institutions. Moreover, we investigate the perinatal factors associated with the Edinburgh postnatal depression scale (EPDS).MethodsThis prospective cohort study was conducted at three medical institutions that commonly encounter cases with social issues. Pregnant women were assessed using an interview sheet at the first visit (n = 678), at approximately 28 weeks gestation (n = 495), 36 weeks gestation (n = 296), and the postpartum period (n = 822). We investigated the important items identified on the new screening questionnaire (NEW interview sheets) for women needing social support. The items on the interview sheet were scored by multiple linear regression analysis, and the cutoff values were calculated using the receiver operating characteristic curve. The association between perinatal factors and EPDS was assessed using multiple logistic regression analyses.ResultsThe study included 166 cases for which all NEW interview sheets for all periods were available. NEW interview sheets and stepwise screening tools during the first and second trimester were developed in which 2.5% of pregnant women were identified as requiring social support, respectively. The factors associated with EPDS ≧ 9 were “Women who felt confused/troubled or did not feel anything to be pregnant” (adjusted odds ratio [aOR]: 6.51, 95% confidence interval [CI]: 1.62–26.15), “Maternal mental disorder” (aOR 4.38; CI 1.06–18.10), “Consultation request at first visit” (aOR 3.22; CI 1.09–9.45), and “Women who have difficulty or anxiety about pregnancy during the second trimester” (aOR 3.14; CI 1.29–7.67).ConclusionsWe created the NEW interview sheets and screening tools during the first and the second trimester. Future studies are needed to validate these screening tools.

Abstract Background and Aim Venipuncture for blood collection elicits fear and pain in children. We investigated factors that affect satisfaction with health checkups that included blood collection in healthy 7–8‐year‐old children who underwent blood collection with topical anesthesia. Method Two studies, one questionnaire survey, and the other structured interviews were conducted to gather insights and understand the emotions of 492 and 20 children, respectively. Results We found that the following six points can be applied to encourage children to assess their experience of blood collection positively: (1) prior information using a pamphlet; (2) telling the children that the volume of blood drawn will be small; (3) carefully explaining the risk and benefit of topical anesthesia; (4) conducting the blood collection process swiftly; (5) praising and thanking the children's effort and cooperation; and (6) explaining the results of the research to the children if their blood is going to be used for research. Conclusion The findings indicate that with appropriate measures to reduce pain and fear, children's initial negative feelings toward blood collection can be replaced by positive feelings after the procedure.

Abstract We aimed to determine mortality risk in underweight patients with diabetic nephropathy for microalbuminuria or macroalbuminuria. We analyzed mortality and death‐cause data from BioBank Japan, with baseline years 2003–2007. We analyzed mortality rates from all causes and ischemic heart disease, according to body mass index (

BackgroundClinical or epidemiological conclusions remain undecided on the direct effects of active and second-hand smoking during pregnancy on childhood obesity. Urinary cotinine (UC) concentration, an accurate and quantitative marker for smoking, may elucidate the dose-dependent relationship between smoking during pregnancy and childhood obesity. To analyze the relationship between UC concentration and smoking questionnaire (SQ) classes for active and second-hand smoking in pregnant mothers and trajectory of infant Kaup index (body mass index: BMI).MethodsThis multicenter prospective cohort study was conducted using a list-wise complete set of 35829 among 89617 mother-infant singleton pairs, recruited between 2011 and 2014, in the Japan Environment and Children’s Study (JECS). Pairs were categorized according to UC levels (1 to 4 classes) or SQ (0 to 4 classes).ResultsMaternal BMI at delivery was the highest in UC class 4 (highest). Maternal and paternal education of ≥16 years and annual household income were lowest in UC class 4. Infant BMI was lower at birth, but trends in BMI and ΔBMI were higher from six to 36 months step-wise in the UC classes. The above tendency was observed in the list-wise complete dataset but was emphasized after multiple imputations and corrections of cofounders. UC concentration in five SQ classes largely fluctuated, and the relationship between SQ classes and trends in BMI and ΔBMI was not statistically significant.ConclusionInfants from high UC mothers had a low BMI at birth, increasing from six to 36 months of age. UC concentrations, but not smoking questionnaire classes, predict infant BMI trajectory, suggesting that active and second-hand smoking affect child obesity in a dose-dependent manner.

Background: Unintentional injury is a major cause of morbidity and mortality among young children in developed countries. In this national study, we examined the role of municipality-level safety checklist implementation for reducing risky child-safety-related parental behaviors. Methods: Nationwide data were collected to evaluate the impact of the Healthy Parents and Children 21 initiative of the Japanese government. Questionnaires related to safety checklist implementation were administered to a random sample of municipal offices and to parents at the child’s routine 1.5-year health exam on parental behaviors related to child safety. Adjusting for municipality and individual-level variables, multilevel analysis was used to examine the relationship between municipality checklist implementation (4-month health exam) and six child-safety-related parental behaviors at the 1.5-year health exam. Results: Families (n = 23,394) across 371 municipalities in Japan were included in this study; 5.6% of municipalities implemented a child safety intervention. Living in a municipality with a checklist intervention was associated with reduction in certain risk behaviors (not keeping tobacco/ashtray and candy out of the reach of infants, not using a car seat, not having a lock on bathing room door). However, after additionally taking into account municipality-level residual effects, only the “tobacco” behavior showed association with municipality of residence (Interval odds ratio, 0.25–0.94) and others were weak in the context of other potential municipality-level influences. Conclusions: A municipality-level intervention taking a checklist-based approach at the 4-month health exam in Japan appears to promote certain child safety behaviors in parents with children around 1.5 years of age.

Abstract Background Unplanned pregnancy is a public health issue with adverse consequences for maternal and neonatal health. In Japan, the prevalence of unplanned pregnancy was 46.2% in 2002. However, few studies have investigated this topic, and there is little recent data from Japan. We described and examined the prevalence and determinants of unplanned pregnancy among rural women in Japan from 2011 to 2016. Methods We used cross-sectional data from a community-based cohort study (Project Koshu). Data were collected from 2011 to 2016 via a self-report questionnaire included in the Maternal and Child Health Handbook of Japan. Pregnancy intention was measured as a binary variable (planned or unplanned). Univariate and multivariate logistic regression analyses were performed to examine factors associated with unplanned pregnancy, with results reported as odds ratios (ORs) and 95% confidence intervals (CIs). We conducted sensitivity analyses with different definitions of pregnancy intention to assess the robustness of the results. The significance level was set at 5%. Results Of the 932 participants (mean ± standard deviation age at baseline: 31.3 ± 5.2 years), 382 (41%) pregnancies were reported as unplanned. The multivariate analyses showed that maternal age (+ 1 year: OR = 0.94, 95% CI: 0.92–0.97, p

We aimed to determine the risk of perinatal complications during delivery in mothers with non-normal glucose tolerance in a large Japanese birth cohort. We analysed data of 24,295 neonate–mother pairs in the Japan Environment and Children’s Study cohort between 2011 and 2014. We included 67 mothers with type 1 diabetes, 102 with type 2 diabetes (determined by questionnaire), 2,045 with gestational diabetes (determined by diagnosis), and 2,949 with plasma glucose levels ≥140 mg/dL (shown by a screening test for gestational diabetes). Gestational age, birth weight, placental weight, and proportions of preterm birth, and labour and neonatal complications at delivery in mothers with diabetes were compared with those in mothers with normal glucose tolerance. Mean gestational age was shorter in mothers with any type of diabetes than in mothers without diabetes. Birth weight tended to be heavier in mothers with type 1 diabetes, and placental weight was significantly heavier in mothers with type 1 and gestational diabetes and elevated plasma glucose levels (all p

ObjectiveTo determine the climate conditions that affect the incidence of atopic dermatitis from infancy to 3 years old.Study designWe analyzed 100,303 children born from 2011 to 2014 for follow-up until 3 years old using cohort data from the Japan Environment and Children's Study. The study included 15 Regional Centers, including 19 prefectures across Japan. We used meteorological data of the Japan Meteorological Agency. We calculated the hazard ratio (HR) of the standard deviation and low vs. high mean values of several climate conditions in children in their first 6 months of life to determine the incidence of atopic dermatitis.ResultsThe Kaplan-Meier curve showed that children born in the months of October to December had the highest incidence of atopic dermatitis. Among climate conditions, a one standard deviation increase in the temperature (HR = 0.87), minimum temperature (HR = 0.87), and vapor pressure (HR = 0.87) showed the lowest HRs for the incidence of atopic dermatitis. These results were confirmed by an analysis by strata of the birth season. A low vapor pressure (HR = 1.26, pConclusionAmong climate conditions, a low vapor pressure is the most strongly associated with a high incidence of atopic dermatitis. Measuring vapor pressure may be useful for preventing atopic dermatitis.

Abstract Background and Aims Early‐term birth between 37 and 38 weeks of gestation increases the risk of mortality and morbidity. This study investigated the status and impact of early‐term birth among neonates born by cesarean section in Japan. Methods All singleton live births that had data of gestational age at birth available in the Japan Environment and Children's Study (JECS), a nationwide birth cohort study launched in 2011, were eligible for this study. Neonates born by cesarean delivery at term without indications for early delivery were included to examine the association between early‐term birth and respiratory distress at birth. The gestational age at birth was categorized as 37 weeks 0 day to 38 weeks 6 days (early‐term), 39 weeks 0 day to 40 weeks 6 day (full‐term), and 41 weeks 0 day to 41 weeks 6 days (late‐term). Respiratory distress at birth included respiratory distress syndrome, transient tachypnea, and difficulty in breathing after birth. Univariable and multivariable analyses were performed using logistic regression models with a two‐tailed significance level of 5%. All statistical analyses were performed using SAS, version 9.4, for Windows (SAS Institute, Cary, NC). Results In total, 32 078 of 100 011 (32.1%) neonates had early‐term birth. At 37 gestational weeks, 49.7% of the deliveries were via cesarean section, and half of the cesarean deliveries were due to a previous cesarean section. Among the 10 051 neonates born by elective cesarean delivery at term, neonates with early‐term births were more likely to have respiratory distress at birth (adjusted odds ratio: 4.19; 95% confidence interval, 1.70, 10.34) than those born at full term. Conclusions Early‐term birth is associated with a high risk of respiratory distress in births involving cesarean delivery without indication for early delivery. There is a need for guidelines for early delivery considering adverse effects of early‐term births.

Objective To compare the incidence of atopic dermatitis in children aged from 6 months to 3 years across birth seasons and climate conditions.Design Cohort study.Setting Fifteen regional centres across Japan.Participants A total of 100 304 children born from 2011 to 2014.Exposure Birth month, and mean sunshine duration (short/long) and humidity (high/low) in the first 6 months of life.Primary outcome measure Incidence of atopic dermatitis.Results The highest incidence of atopic dermatitis was in children born in the months of October to December. The lowest incidence of atopic dermatitis was in the months of April to June and in periods with a long duration of sunshine and high humidity. Low humidity was significantly associated with a higher incidence of atopic dermatitis. However, this significant difference disappeared when the birth season and parental history of allergic disease were considered in multivariate analysis.Conclusions In Japan, being born in the late autumn to early winter months is associated with a risk of developing atopic dermatitis until the age of 3 years. Sunshine duration and humidity from birth to 6 months of age are not associated with the incidence of atopic dermatitis.

[This corrects the article DOI: 10.1371/journal.pone.0243702.].

Floating toe (FT) is a frequently seen condition in which a toe is inadequately in contact with the ground. Although toes play an important role in stabilizing standing posture and walking, many aspects of the effects of FT on the body remain unclear. To our knowledge, there have been no reports about the relationship between FT and postural stability, especially in children. This study aimed to clarify the prevalence of FT and its relationship with static postural stability in children. Of the 400 children aged 8 years who participated in our cohort study, 396, who were examined for static postural stability, were included in this study. Postural stability and FT were assessed using a foot pressure plate. The sway path length of the center of pressure and the area of the ellipse defined as the size of the area marked by the center of pressure, were measured as an evaluation of static postural stability. We calculated the "floating toe score (FT score: small FT score indicates insufficient ground contact of the toes)" using the image of the plantar footprint obtained at the postural stability measurement. The rate of FT was elevated at more than 90%, and the FT score in the eyes-closed condition was significantly higher than that in the eyes-open condition in both sexes. The FT score significantly correlated with the center of pressure path and area. Our results suggest that ground contact of the toes is not directly related to static postural stability in children, but it may function to stabilize the body when the condition becomes unstable, such as when the eyes are closed.

The eligibility of COVID-19 vaccines has been expanded to children aged 12 and above in several countries including Japan, and there is a plan to further lower the age. This study aimed to assess factors related to parental COVID-19 vaccine hesitancy. A nationwide internet-based cross-sectional study was conducted between May 25 and June 3, 2021 in Japan. The target population was parents of children aged 3-14 years who resided in Japan, and agreed to answer the online questionnaire. Parental COVID-19 vaccine hesitancy (their intention to vaccinate their child) and related factors were analyzed using logistic regression models. Interaction effects of gender of parents and their level of social relationship satisfaction related to parental vaccine hesitancy was tested using log likelihood ratio test (LRT). Social media as the most trusted information source increased parental vaccine hesitancy compared to those who trusted official information (Adjusted Odds Ratio: aOR 2.80, 95% CI 1.53-5.12). Being a mother and low perceived risk of infection also increased parental vaccine hesitancy compared to father (aOR 2.43, 95% CI 1.57-3.74) and those with higher perceived risk of infection (aOR 1.55, 95% CI 1.04-2.32) respectively. People with lower satisfaction to social relationships tended to be more hesitant to vaccinate their child among mothers in contrast to fathers who showed constant intention to vaccinate their child regardless of the level of satisfaction to social relationship (LRT p = 0.021). Our findings suggest that dissemination of targeted information about COVID-19 vaccine by considering means of communication, gender and people who are isolated during measures of social distancing may help to increase parental vaccine acceptance.

To clarify the physical and mental conditions of children during the coronavirus disease 2019 pandemic and consequent social distancing in relation to the mental condition of their caregivers. This internet-based nationwide cross-sectional study was conducted between April 30 and May 13, 2020. The participants were 1,200 caregivers of children aged 3-14 years. Child health issues were categorized into "at least one" or "none" according to caregivers' perception. Caregivers' mental status was assessed using the Japanese version of the Kessler Psychological Distress Scale-6. The association between caregivers' mental status and child health issues was analyzed using logistic regression models. Among the participants, 289 (24.1%) had moderate and 352 (29.3%) had severe mental distress and 69.8% of children in their care had health issues. The number of caregivers with mental distress was more than double that reported during the 2016 national survey. After adjusting for covariates, child health issues increased among caregivers with moderate mental distress (odds ratio 2.24, 95% confidence interval 1.59-3.16) and severe mental distress (odds ratio 3.05, 95% confidence interval 2.17-4.29) compared with caregivers with no mental distress. The results highlight parents' psychological stress during the pandemic, suggesting the need for adequate parenting support. However, our study did not consider risk factors of caregivers' mental distress such as socioeconomic background. There is an urgent need for further research to identify vulnerable populations and children's needs to develop sustainable social support programs for those affected by the outbreak.

Abstract Background Many reports argue that sleep is important for children’s health, learning, and academic performance. The purpose of this longitudinal study was to examine the association between sleep and the development of social competence in infants. Methods This study was conducted as part of a Japan Science and Technology Agency (JST) project. Caregivers responded to the Japan Children’s Study Sleep Questionnaire when children were 18 months old. The interactions of caregivers and children were observed when children were 18, 30, and 42 months old, and rated with the Interaction Rating Scale, which is a measure of social competence. Results Nocturnal sleep duration of more than 10 h and an earlier bed time than 22:00 were significantly correlated with two trajectory groups (low point and high point transition groups) of children’s social competence at 18, 30, and 42 months. Further, total sleep duration of more than 12.25 h and an earlier bed time than 22:00 were significantly correlated with the trajectory of children’s social competence at 18, 30, and 42 months. Conclusions Sleep duration and sleep onset time are important factors in children’s development of social competence. Trial registration The ethics committee of the JST approved this study on March 19, 2001. The registration number is 356-1.

Pregestational weight status and maternal smoking during pregnancy are significantly associated with fetal and childhood growth. However, few studies have examined associations between childhood growth and combinations of these factors using multilevel analysis. This study aimed to describe differences in childhood growth trajectories according to these combinations, using data from a prospective cohort study in Japan. The study participants were 1,973 women and their singletons, who were born between April 1, 1991 and March 31, 2003. Children were categorized according to whether they were born to normal-weight, nonsmoking mothers (NN); normal-weight, smoking mothers (NS); underweight, nonsmoking mothers (UN); underweight, smoking mothers (US); overweight, nonsmoking mothers (ON); or overweight, smoking mothers (OS). Birth weight and anthropometric data were collected from 1,965 children at birth (99.6%), 1,655 aged 3 (83.9%), 1,527 aged 5 (77.4%), 1,497 aged 7-8 (75.9%), and 1,501 aged 9-10 (76.1%). Multilevel analysis examining both individual and age as different level variables according to sex was used to describe the trajectories of body mass index z scores for statistical analyses. Although children of the OS group were the leanest at birth, their body mass indices had increased rapidly by 3 years of age. Moreover, body mass index was also likely to increase in boys in the NS and ON groups. A different trend was observed in girls. Body mass index decreased from 5 years of age in girls in the US group. There were no remarkable differences in body mass index trajectories between children in the other groups. In conclusion, childhood growth trajectories differed according to combinations of pregestational weight status and maternal smoking during pregnancy. Further, there were sex-related differences in the associations between childhood growth and factor combinations.

Purpose The clinical guideline on gestational weight gain for Japanese twin pregnant women has not been presented in Japan so far. As a process of determining optimal weight gain, this study aimed to describe the gestational weight gain by pregnancy period in Japanese twin pregnant women with favorable perinatal outcomes. Methods This descriptive study used the data of the Japan Environment and Children's Study ( JECS) that recruited pregnant women between 2011 and 2014 in Japan. From JECS data, we selected twin pregnant women with favorable perinatal outcomes, which were defined from the aspects of newborn's birth weight, gestational birth weeks and maternal complications, and their maternal weight gain at specific weeks of pregnancy were estimated retrospectively using a regression curve. Estimated maternal weight gain at each time was compared with United States of America Institute of Medicine (IOM) criteria which is cited to Japanese clinical guideline. Results The 321 twin pregnancies were analyzed. The estimated median weight gain at 36 weeks in Japanese twin pregnant with favorable perinatal outcomes was 12.98 kg (interquartile range: 9.89-16.07), and the actual weight gain at delivery was 13.00 kg (10.00-16.23). The estimated cumulative weight gain at 13, 26, and 36 weeks were 1.08 kg (-0.57-2.38), 8.22 kg (5.78-9.84), and 13.10 kg (10.18-16.15) for women with normal BMI, 1.87 kg (0.05-2.78), 9.40 kg (7.68-11.44), and 14.57 kg (12.47-18.08) for women with underweight BMI, and 0.52 kg (-1.27-1.59), 4.10 kg (2.35-7.01), 8.58 kg (5.05-11.52) for women with overweight BMI, respectively. Most of the median values observed in this study did not reach even the lowest limit of IOM criteria. Conclusion Gestational weight gain at each trimester based on the IOM criteria seems excess for Japanese twin pregnant women. [ABSTRACT FROM AUTHOR]