Hidekuni Inadera

Purpose: Hypertensive disorders of pregnancy (HDP) are a leading cause of maternal and perinatal morbidity. Although n-3 polyunsaturated fatty acids (PUFAs) in fish may prevent HDP, evidence from Japanese populations, particularly regarding the preconception period, remains limited. To examine associations between fish and PUFA intake before and during pregnancy and the risk of HDP using data from a nationwide Japanese birth cohort. Methods: This analysis included 86,009 women from the Japan Environment and Children’s Study. Dietary fish and n-3/n-6 PUFAs intake was assessed using a validated food-frequency questionnaire administered in early pregnancy (median gestational age, 15.0 weeks [interquartile range (IQR) 12.0–19.0]) to capture intake before pregnancy, and in mid to late pregnancy (median gestational age, 27.0 weeks [IQR 25.0–30.0]). Participants were categorized into quintiles of intake. Logistic regression models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for HDP, early-onset HDP (Eo-HDP < 32 weeks), and late-onset HDP (Lo-HDP ≥ 32 weeks). Missing data were addressed with multiple imputation. Results: In the overall population, higher fish intake before pregnancy was associated with reduced risks of Eo-HDP in the Q5 groups, whereas higher fish intake during pregnancy was associated with reduced risks of overall HDP in Q4. In analyses restricted to nulliparous women, higher pre-pregnancy fish intake was associated with a lower risk of Eo-HDP (Q4: aOR 0.57; 95% CI 0.34–0.97; p for trend = 0.02), and higher fish intake during pregnancy was associated with a lower risk of Lo-HDP (Q4: aOR 0.79; 95% CI 0.64–0.96). Total n-3 PUFA intake showed significant associations with HDP only in some analyses. Sensitivity analyses using a 34-week cutoff yielded consistent results. Conclusion: Fish intake before pregnancy was associated with lower risk of Eo-HDP, whereas intake during pregnancy was linked to reduced risk of Lo-HDP. Sustained fish consumption from preconception through pregnancy may help prevent HDP and inform global nutritional guidance, including preconception care. Trial registration: The Japan Environment and Children’s Study, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000035091 (Registration no. UMIN000030786).

Purpose To identify factors associated with mother-to-infant bonding difficulties (MIBD) in mothers without prior postnatal depression and to elucidate the prevalence. Methods A total of 64,938 mother–child pairs who had registered between 2011 and 2014 in a nationwide birth cohort study called the Japan Environment and Children’s Study (JECS) were analysed. MIBD was assessed using the Mother-to-Infant Bonding Scale Japanese version (MIBS-J). Prior postnatal depression was defined as an Edinburgh Postnatal Depression Scale score ≥ 9 at both 1 month and 6 months postpartum, and mothers who met this criterion were excluded. Mothers with a MIBS-J score ≥ 5 were considered to have MIBD. Cut-offs of ≥ 3 were set for MIBS-J subscale scores for lack of affection (LA)and anger/rejection (AR). We set 30 factors as exposures, and data were subjected to logistic regression analysis. Results The prevalence of MIBD, LA, and AR among those without prior postpartum depression was 7.7%, 3.9%, and 11.7%, respectively. The most strongly associated factors were ‘feeling difficulty in holding the baby when they were cranky or arching their back’ (AOR: 3.45 [2.96–4.03]) and ‘negative feelings towards the pregnancy’ (AOR: 2.42 [2.20–2.65]). ‘High social support’ (AOR: 0.45 [0.41–0.49]) was strongly associated with the absence of MIBD without prior postnatal depression. Conclusions In this study, the prevalence of MIBD among women without prior postnatal depression was 7.7%. MIBD without prior postnatal depression was strongly associated with ‘difficulty holding the baby when they were cranky or arching their back’, ‘low social support’, and ‘negative feelings towards the pregnancy’.

Children have up to three3 times the annual sun exposure of adults. This cross-sectional study evaluated sun protection behaviorbehaviour, related factors, and the incidence of photosensitivity in Japanese children. A self-administered questionnaire administered to mothers of second2nd-grade children as part of the Toyama Adjunct Study of the Japan Environment and Children’s Study was used and analyzedanalysed (n=1,691). The results showed that 67.5 % of children always or sometimes used sunscreen when going out for a long time, while 73.2 % used at least one method of sun protection when swimming in an outdoor pool. BehaviorsBehaviours related to sun exposure were related to the sex of the child, Fitzpatrick skin phototype, skin symptoms after sun exposure, annual household income, father’s highest educational level, and maternal age. The incidence of photosensitivity disorders was 0.5 %. Diagnoses included polymorphous light eruptions in 4 (50%) and solar urticaria in 2 (25%). However, 5.9 % of children had skin symptoms after sun exposure, but were undiagnosed. In general, photosensitivity is rarely encountered in pediatricpaediatric patients; in this study, we determined its prevalence in children in Japan. Six factors appeared to be relevant to behaviorsbehaviours related to sun exposure. Further investigation is required to confirm these findings.

Breastfeeding has been linked to children’s susceptibility to allergic diseases. However, few large epidemiological studies have correlated breastfee

The number of births by caesarean section (CS) is increasing worldwide. In line with this trend, there is growing interest in the neurodevelopmental outcome of children born by CS. This study examined the relationship between the mode of delivery and suspected neurodevelopmental delay in young children. A total of 53,716 mother-child pairs participating in the Japan Environment and Children's Study, a representative Japanese cohort study of children, were included in the analysis of the association between CS and suspected developmental delay, as assessed by the Ages and Stages Questionnaires, Third Edition, in 3-year-old children. Multivariate logistic regression analysis was performed to calculate adjusted odds ratios (aORs) with 95% confidence intervals (CIs). No significant overall relationship was found between mode of delivery and suspected developmental delay. In an analysis by sex, CS was associated with increased risk of suspected gross motor developmental delay (aOR 1.27, 95% CI 1.07-1.49) in boys and increased risk of suspected fine motor developmental delay (aOR 1.34, 95% CI 1.11-1.63) in girls. These results suggest that there may be a relationship between CS and suspected motor developmental delay at the age of 3 years.

Background Breastfeeding plays a vital role in preventing childhood infections and enhancing many aspects of long-term health. In this study, we investigated the link between feeding and sleep duration and considered the underlying mechanism of the observed effects, particularly the role of nutrients in breast milk and formula as well as that of the brain–gut axis. Few studies have examined the relationship between breastfeeding and infant sleep, and thus there is a need for a prospective study involving a large population. Subjects This study analyzed data on 82,918 mother–infant pairs from the Japan Environment and Children’s Study, a nationwide birth cohort study. We examined the association of breastfeeding pattern over the first 6 months of life by comparing sleep duration at 1 year of age between babies exclusively formula-fed for 6 months and those breastfed for <6 months, those breastfed for 6 months with formula, and exclusively breastfed for 6 months. Results The adjusted odds ratio (95% confidence interval) for short sleep duration (<11 h/day) at 1 year of age was 0.84 (0.73–0.97) for breastfed for <6 months, 0.79 (0.69–0.91) for breastfed for 6 months with formula, and 0.77 (0.67–0.89) for exclusively breastfed for 6 months compared with exclusively formula-fed for 6 months (Formula alone). Conclusions Breastfeeding during the first 6 months of life was associated with a decreased risk of short sleep duration in 1-year-old infants.

Background: It has been suggested that working long hours affects workers’ mental health, although findings have been inconsistent. In this study, we investigated the association of working hours with psychological distress in a population of Japanese men with pregnant partners, using data from the Japan Environment and Children’s Study. Methods: Data from 44,996 men were analyzed and weekly working hours were classified into six groups. The Kessler Psychological Distress Scale (K6) was used to assess mental health. Each of the six items were assessed on a 5-point scale (0–4), with a total score of 0–24 and higher scores indicating greater psychological distress. A total score of 5–12 was considered to indicate moderate psychological distress and a score of ≥13 to indicate severe psychological distress. To investigate the association of working hours with psychological distress, multinomial logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Results: The results showed that after adjusting for covariates, weekly working hours was positively associated with moderate and severe psychological distress. Compared with men who worked ≤40 h per week, those who worked >55 to ≤65 h or >65 h per week had significantly higher ORs (95% CIs) for moderate psychological distress, 1.12 (1.03–1.21) and 1.34 (1.24–1.45), respectively, and those working >65 h per week had significantly higher OR, 1.84 (1.47–2.32) for severe psychological distress. For these two outcomes, a significant p for trend (<.0001) was observed in both the crude and adjusted models. Conclusion: The results of this study suggest that the greater time constraints resulting from working long hours are associated with psychological distress in Japanese men with pregnant partners.

Bonding disorders are known to have significant negative effects on mother-to-infant interactions and nurturing behaviours. In this study, we examined the relationship of dietary intake of omega-3 polyunsaturated fatty acids (PUFAs) and fish with mother-to-infant bonding at 1 and 6 months postpartum. Participants were 91,147 mothers enrolled in the ongoing Japan Environment and Children’s Study. Omega-3 PUFA intake was measured using the Food Frequency Questionnaire administered during pregnancy (mean ± SD, 27.9 ± 6.7 weeks of gestation). Bonding was assessed using self-report questionnaires administered at 1 and 6 months postpartum. The lower the LMF (lack of maternal feeling) factor score, AC (anxiety about caregiving) factor score, and total score, the better the bonding. In analyses based on the lowest quintile of omega-3 PUFA intake, the odds ratios for LMF, AC, and total scores tended to decrease as the quintile increased at 1 and 6 months postpartum. Higher omega-3 PUFA intake during pregnancy was associated with better bonding. Thus, habitual intake of omega-3 PUFAs during pregnancy may help smoothly build attachment to the child and reduce a lack of maternal feeling and parental anxiety.

The relationship of pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) with continued breastfeeding (BF) in Japanese women remains unclear. To evaluate different maternal pre-pregnancy BMI and GWG categories according to the initial BMI, we conducted an analysis of continued BF until 6 months postpartum in a large Japanese cohort. This study used data from the Japan Environment and Children’s Study, which included approximately 100,000 pregnant women. Pre-pregnancy BMI (kg/m2) was categorized as underweight (BMI < 18.5), normal weight (BMI 18.5–24.9), and overweight (BMI 25.0–29.9). GWG was categorized as insufficient, optimal, and excessive based on the 2021 criteria from the Japanese Society of Obstetrics and Gynecology. Continued BF for the first 6 months postpartum was categorized into 3 patterns: exclusive BF (EBF), non-EBF type-I (6 months of BF with formula), and non-EBF type-II (< 6 months of BF). Logistic regression analysis was conducted to evaluate the association of pre-pregnancy BMI and GWG with continued BF. Normal BMI and optimal GWG and EBF were used as reference values while controlling for covariates. Of 82,129 women with singleton pregnancies, BMI was categorized as underweight in 16.6%, normal weight in 75.3%, and overweight in 8.1%. The rate of EBF in these groups was 37.1% for underweight, 37.2% for normal weight, and 26.8% for overweight. In underweight women, both insufficient and excessive GWG were associated with higher rates of non-EBF type-II. In normal-weight women, insufficient and excessive GWG were associated with higher rates of non-EBF type-II. Overweight women showed higher rates of non-EBF type-I and type-II, irrespective of GWG. Our results indicate that the effects of GWG on continued BF were associated with pre-pregnancy BMI. Adequate GWG should be recommended to underweight and normal-weight women to promote BF. Efforts toward the prevention of overweight prior to pregnancy should be encouraged to enhance BF.

Previous studies have demonstrated that paternal involvement in childcare for infants up to 6 months of age can prevent injuries in children up to 18 months of age. However, the relationship after 18 months of age has not been clearly established. Therefore, this study investigated the association between paternal involvement in childcare at 6 months of age and injuries in children between birth and 4 years of age. This study analysed data from 72,343 children and mothers who participated in the Japan Environment and Children’s Study (JECS). Seven items of paternal involvement in childcare at 6 months of age—indoor play, outdoor play, feeding the child, diaper changing, dressing, bathing, and putting the child to bed—were assessed using a 4-item Likert-type scale. The total score was calculated from the responses (0–21) and divided into three tertiles: low (0–11), middle (12–14), and high (15–21). Children were asked about trauma and burn injuries occurring from birth to 4 years of age. Multivariable logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs). The incidence of traumatic injury in children from birth to 4 years of age was 5.0%, and the incidence of burn injury was 4.0%. The association of trauma and burn with the risk of child injury by tertile of paternal involvement in childcare at 6 months of age showed a protective effect for trauma (P for trend = 0.013). Responses of ‘seldom’ ‘sometimes’, or ‘all the time’ to the items playing at home, playing outdoors, feeding, bathing, and putting the child to sleep were more likely to be associated with a lower risk of trauma in children compared with responses of ‘never’. There was no association between paternal involvement in childcare and burn injuries in children. Paternal involvement in childcare at 6 months of age was associated with a lower risk of trauma in children, and a protective effect against traumatic injuries was shown in 5 of the 7 items of paternal involvement in childcare.