Paternal involvement in infant care and developmental milestone outcomes at age 3 years: the Japan Environment and Children's Study (JECS).

BACKGROUND: In developed countries, the time fathers spend on childcare has increased steadily in recent decades. However, studies on the relationship between paternal care and child outcomes remain scarce. Thus, we examined the association between paternal involvement in childcare and children's developmental outcomes. METHODS: We used Japan's largest birth cohort data, the Japan Environment and Children's Study, to examine the relationship between paternal involvement in childcare at the child's age of 6 months and developmental milestone outcomes at the child's age of 3 years (n = 28,050). Developmental delays were assessed with Ages and Stages Questionnaire. Potential mediation by maternal parenting stress at the child's age of 1.5 years was also examined. We used log-binomial regression analyses to estimate risk ratios. RESULTS: Fathers' high involvement in childcare was associated with a lower risk of developmental delay in gross-motor, fine-motor, problem solving, and personal-social domains compared with low involvement, adjusting for potential confounders. For example, the risk ratio with 95% confidence intervals was 0.76 [0.67, 0.86] for the gross-motor domain. We also observed that the associations were partially mediated by maternal parenting stress. CONCLUSIONS: Fathers' active involvement in childcare during infancy may promote young children's development, partially by reducing maternal parenting stress. IMPACT: Using Japan's largest birth cohort data (Japan Environment and Children's Study), we showed that paternal involvement in infant care might benefit young children's development. Fathers' active involvement in infant care was associated with a lower risk of developmental delays in gross-motor, fine-motor, problem solving, and personal-social domains. Maternal parenting stress may mediate the association between paternal involvement in infant care and child development outcomes at 3 years.

Paternal involvement in childcare and housework and mothers' spanking behavior: The Japanese longitudinal survey of newborns in the 21st century.

BACKGROUND: No previous study reported an association between paternal involvement in childcare and housework and maternal physical punishment. METHODS: Using data from the Japanese Longitudinal Survey of Newborns in the 21st century (N = 38,554), we analyzed responses about fathers' involvement in childcare and housework at 6 months and mothers' spanking of children at 3.5 years. Fathers' involvement in childcare and housework was scored and categorized into quartiles. Spanking frequency was asked in the "often", "sometimes", or "not at all" categories. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the mothers' often spanking children were computed for the fathers' involvement in childcare and housework. We also stratified the association by fathers' working hours (40-49, 50-59, or ≥ 60 hours/week). RESULTS: Among the 16,373 respondents, the proportion of mothers who often spanked their children was 4.8%. Compared with the lowest quartile, a higher frequency of paternal involvement in housework was associated with a lower risk of spanking children (p trend = 0.001). Adjustment for covariates attenuated the association, but significant association was observed in the 3rd quartile of paternal involvement in housework [OR (95% CI): 0.77 (0.62-0.96)]. When the fathers worked fewer than 50 hours a week, a significant negative association was observed between the fathers' frequency of childcare and the likeliness of the mothers' spanking their children (p trend = 0.02). CONCLUSIONS: The fathers' active involvement in childcare and housework could reduce the mothers' physical punishment for their children.

Prevalence and Associated Factors of Psychological Distress Among Single Fathers in Japan.

BACKGROUND: In Japan, ten percent of single-parent households are led by fathers. Taking care of children as a single father is very stressful and could put a strain on their health. It is very important to prevent and identify psychological distress among fathers for both their own health and to avoid negative impacts on children. This study aims to determine the prevalence of and factors associated with psychological distress among single fathers and understand how it is different from partnered fathers. METHODS: We used data from the Comprehensive Survey of Living Conditions 2016. Psychological distress, assessed using the K6 scale, was analyzed among 868 single and 43,880 partnered fathers. Logistic regression analysis was performed to assess the risk factors for psychological distress, such as employment type, sleep hours, and smoking and drinking habits. RESULTS: Single fathers had a higher proportion (8.5%) of psychological distress compared to partnered fathers (5.0%). A larger percentage of single fathers had a lower educational level and were more likely to be non-regular workers, self-employed, or unemployed than partnered fathers. Among single fathers, the crude and adjusted odds ratio for employment type and sleep hours were significantly associated with psychological distress. CONCLUSION: As single parents who are self-employed or directors are likely to have significantly reduced psychological distress than those with regular jobs, measures are needed to improve the work-family balance for non-self-employed fathers. There is a need to provide greater financial assistance and other social welfare support to single parents to ensure their and their children's good health.

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.

Effects of Dexmedetomidine on Brain and Inflammatory Outcomes In Pediatric Cardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

OBJECTIVE: Dexmedetomidine use decreases adverse neurocognitive outcomes in adults undergoing cardiovascular surgery, but its effect has been unclear in children with congenital heart disease. METHODS: The authors conducted a systematic review using the PubMed, Embase, and Cochrane Library databases for randomized controlled trials (RCTs) that compared intravenous dexmedetomidine with normal saline during pediatric cardiac surgery under anesthesia. Published randomized controlled trials that evaluated children aged <18 years who underwent congenital heart surgery were included. Nonrandomized trials, observational studies, case series and case reports, editorials, reviews, and conference papers were excluded. The quality of the included studies was assessed using the Cochrane revised tool for assessing risk-of-bias in randomized trials. Meta-analysis was performed to estimate the effects of intravenous dexmedetomidine on brain markers (neuron-specific enolase [NSE], S-100ß protein) and inflammatory markers (interleukin-6, tumor necrosis factor [TNF]-α, nuclear factor kappa-B [NF-κB]) during and after cardiac surgery, using random-effect models for standardized mean difference (SMD). RESULTS: Seven RCTs involving 579 children were eligible for the following meta-analyses. Most children underwent cardiac surgery for atrial or ventricular septum defects. Pooled analyses (5 treatment groups in 3 RCTs with 260 children) showed that dexmedetomidine use was associated with reduced serum levels of NSE (pooled SMD, -0.54; 95% CI, -0.96 to -0.12) and S-100ß (pooled SMD, -0.85; 95% CI, -1.67 to -0.04) within 24 hours after the surgery. Also, dexmedetomidine use was associated with reduced levels of interleukin-6 (pooled SMD, -1.55; 95% CI, -2.82 to -0.27; 4 treatment groups in 2 RCTs with 190 children). In contrast, the authors observed similar levels of TNF-α (pooled SMD, -0.07; 95% CI, -0.33 to 0.19; 4 treatment groups in 2 RCTs with 190 children) and NF-κB (pooled SMD, -0.27; 95% CI, -0.62 to 0.09; 2 treatment groups in 1 RCT with 90 children) between the dexmedetomidine and control groups. CONCLUSIONS: The authors' findings support the effect of dexmedetomidine on reductions in brain markers among children who undergo cardiac surgery. Further studies would be needed to elucidate its clinically meaningful effects using cognitive functions in the long term, and its effects among children who undergo more complex cardiac surgeries.

Trajectories of fathers' childcare involvement and child behavioral outcomes.

BACKGROUND: Father's closeness and playful behavior influence a child's emotional and cognitive development. In this study, we aimed to assess the long-term association of paternal involvement in childcare at 1-3 years of life on subsequent behavioral outcomes at 8 years of age. METHODS: Data were obtained from the 2010 cohort of the Longitudinal Survey of Newborns in the 21st century in Japan. We used group-based trajectory modeling to predict the trajectory of total childcare scores in surveys 1, 2 and 3 to determine the overall involvement of fathers in childcare during early childhood. The level of fathers' involvement in childcare was categorized as "low", "medium" and "high". Responses from the eighth survey were used to assess child behavioral outcomes using five indicators when the child was 8 years old. Crude and adjusted logistic regression analysis was conducted to estimate the odds ratio (OR) separately for each of the behavioral outcomes of the child. RESULTS: Among the 17,027 father-child dyads included in this study, two-thirds of the fathers were of the age group 30-39 years. Compared to low involvement, children of fathers with high involvement in childcare during the early childhood years were less likely to not want to go to school even after adjusting for covariates (adjusted OR, 0.46; 95% CI: 0.32-0.66). CONCLUSIONS: Children benefit from their fathers' involvement in early childcare activities. To improve a child's well-being, fathers should be encouraged by providing them with a suitable working environment with flexible arrangements and the opportunity to involve in childcare.

Child Maltreatment and Mental Health in Middle Childhood: A Longitudinal Study in Japan.

Toxic stress caused by child maltreatment can lead to adverse mental health outcomes in later life, yet unmeasured confounding has been a major issue in many previous studies. To examine the association between child maltreatment and resilience and behavior problems among early elementary school-age children, we used data from a population-based longitudinal survey targeting all first-grade children in 2015 in Adachi City, a ward in Tokyo, Japan. Children whose caregivers provided valid responses during the 2015 (first grade; ages 6-7 years), 2016 (second grade; ages 7-8 years), and 2018 (fourth grade; ages 9-10 years) waves of the study were included in the analysis (n = 2,920). Fixed-effects regression models revealed that child maltreatment was inversely associated with resilience (ß = -0.89, 95% confidence interval (CI): -1.05, -0.72) and prosocial behavior (ß = -0.03, 95% CI: -0.05, -0.003) and positively associated with behavior problems (ß = 0.32, 95% CI: 0.27, 0.37) over 4 years of follow-up (2015-2018), after controlling for all time-invariant confounders and measured time-varying confounders and survey year. These associations were consistent across sex. Child maltreatment may hamper the development of resilience and prosocial behavior and induce behavior problems in early elementary school children over time. Future researchers should identify modifiable protective factors for better mental health among maltreated children.

Factors related to parenting stress among fathers of preschool children in Japan.

BACKGROUND: Even though fathers participate in childcare at a higher rate than before, there remains a lack of research on the factors that contribute to parenting stress among fathers. This study explored the socioeconomic and demographic factors associated with parenting stress among fathers of preschool children. METHODS: Our study included 17 645 fathers who participated in the 2016 Comprehensive Survey of Living Conditions in Japan. Parenting stress was assessed using a single question. Socioeconomic and demographic factors were predictors. Logistic regression analysis was conducted to estimate the odds ratio (OR) and 95% confidence interval (CI) for parenting stress. RESULTS: Overall, 6.6% fathers experienced parenting stress. Fathers with a youngest child aged 0-2 years were more likely to experience parenting stress than those with a youngest child aged 3-6 (OR: 1.45, 95% CI: 1.25-1.68). Compared with fathers who lived in two-parent households without grandparents, those who lived in single-father households (both with and without grandparents) were more likely to experience parenting stress (OR: 12.13, 95% CI: 5.60-26.29 and OR: 4.19, 95% CI: 2.04-8.60, respectively). Furthermore, there was a significant negative association between education and parenting stress. CONCLUSIONS: Having a child aged 0-2 years, single fatherhood, and higher education were associated with parenting stress among fathers of preschool children. Healthcare professionals need to be aware of these factors when supporting fathers in raising their children.

[Review on the influence of paternal involvement in childcare on mothers, children, and fathers].

Objectives　Recently, paternal involvement in childcare has been gaining public attention in Japan. However, studies on the influences of active paternal involvement remain scarce. This study aimed to review the findings on the influence of paternal involvement in childcare on mothers, children, and fathers themselves from studies conducted in Japan and published mainly after 2010. Additionally, we examined methodological issues that need to be addressed when researchers conduct studies on paternal involvement in the future.Methods　We reviewed 26 journal articles (22 in Japanese and 4 in English) from four databases: "Igaku Chuo Zasshi Web (Japana Centra Revuo Medicina History and Activities)," JSTPlus, JMEDPlus, and PubMed with conditions such as studies conducted in Japan, families with young children, and questionnaire-based quantitative studies. We described respondents (mothers, fathers, or both) and assessed paternal involvement in childcare, outcomes, and findings.Results　We reviewed studies on paternal involvement in childcare published in Japanese after 2010 and English after 2000 and observed two trends across the studies. The first was that if mothers acknowledge active paternal involvement in childcare, mothers' parenting stress seemed to be lower, and they seemed to be happier. Moreover, for children's health and development, active paternal involvement seemed to be associated with positive results, such as prevention of unintentional injuries and obesity. However, in the second trend, we observed that active paternal involvement, assessed by the fathers themselves, were often not associated with lower parenting stress among mothers. We also could not observe a consistent trend on the findings related to the influences on fathers, due to the limited number of studies. We observed that assessment of paternal involvement in childcare was inconsistent across studies included in this review.Conclusion　With more social pressure for fathers to be actively involved in childcare, public interest for the influence would be heightened. For future studies, better ways of assessing the quantity and content of paternal involvement in childcare need to be discussed.

Adachi Child Health Impact of Living Difficulty (A-CHILD) Study: Research Protocol and Profiles of Participants.

BACKGROUND: The Adachi Child Health Impact of Living Difficulty (A-CHILD) study has been conducted since 2015 to clarify the associations between socioeconomic factors and child health, as well as to accumulate data for political evaluation of the child-poverty agenda. This paper describes the purpose and research design of the A-CHILD study and the baseline profiles of participants, together with the future framework for implementing this cohort study. METHODS: We have conducted two types of continuous survey: a complete-sample survey started in 2015 as a first wave study to target first-grade children in all public elementary schools in Adachi City, Tokyo, and a biennial fixed grade observation survey started in 2016 in selected elementary and junior high schools. Questionnaires were answered by caregivers of all targeted children and also by the children themselves for those in the fourth grade and higher. The data of A-CHILD also combined information obtained from school health checkups of all school-grade children, as well as the results from blood test and measurement of blood pressure of eight-grade children since 2016. RESULTS: The valid responses in the first wave were 4,291 (80.1%). The number of households in "living difficulties", such as low household income or material deprivation, stood at 1,047 (24.5%). CONCLUSIONS: The A-CHILD study will contribute to the clarification of the impact of poverty on children's health disparities and paves the way to managing this issue in the community.

Socio-Economic Disparities in Early Childhood Education Enrollment: Japanese Population-Based Study.

BACKGROUND: Accumulating evidence has shown that high-quality early childhood education and care may be an effective way of promoting children's optimal health and development, especially for the most disadvantaged. However, socially disadvantaged families are less likely to enroll children in center-based childcare. In this study, we explored characteristics associated with use of center-based childcare among Japanese families. METHODS: We used data from two Japanese birth cohorts in 2001 (n = 17,019) and 2010 (n = 24,333). Enrollment in center-based childcare was assessed at the ages of three and four years in the 2001 cohort and at the age of three in the 2010 cohort. Logistic regression analyses were conducted. RESULTS: Children in the lowest quintile of household income were 1.54 (95% confidence interval, 1.20-1.98) times more likely to not receive center-based childcare than those in the highest-income quartile at the age of four in the 2001 cohort. Other socio-economic disadvantage (mother's low education, non-Japanese parent, and higher number of siblings) and child's health and developmental problems (preterm birth, congenital diseases, and developmental delay) were also associated with the non-use of center-based childcare at the age of three in the 2001 and 2010 cohorts. CONCLUSIONS: An inverse care law operates in the use of early childhood education (ie, children with the least need enjoy the highest access). Children with socio-economic, health, and developmental disadvantages are at a greater risk of not receiving early childhood education and care. Social policies to promote equal access to early childhood education are needed to reduce future socio-economic inequalities.

Municipality-Level Checklist to Promote Parental Behaviors Related to Prevention of Unintentional Injury in Young Children: A Multilevel Analysis of National Data.

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.

[Association between home environment and children's long hours of internet use: An analysis of Survey on Parent-child Relationship in the Internet Age].

Objectives　The purpose of this study was to investigate the association between home environment and long hours of internet use among Japanese elementary school and junior high school students.Methods　We used data from the Survey on Parent-child Relationship in the Internet Age conducted by the Japanese National Institute for Youth Education in 2017. In the analysis, 2062 children between fifth grade of elementary school and second grade of junior high school from 20 prefectures in Japan were retained after excluding 210 children with no internet use. Exposure variables included children's ownership of internet devices (e.g., smartphones), parents' ways of using a mobile phone or smartphone at home, and the child's relationship to his or her parents. Outcomes were long hours of internet use on a weekday and a weekend day and experiencing a lack of sleep. We defined long hours as three or more hours on a weekday and five or more hours on a weekend day. Odds ratios (OR) and 95% confidence intervals (95%CI) were estimated using logistic regression analyses.Results　Children's ownership of a smartphone or tablet was associated with long hours of internet use and experiencing lack of sleep. Compared to non-owners, adjusted odds ratios for smartphone owners were 2.55 [95%CI: 1.92-3.38] for long hours of internet use on a weekday and 1.66 [95%CI: 1.17-2.34] for lack of sleep. Spending long hours on the internet on the weekend was associated with parents using mobile phones while talking to their children [OR=1.59, 95%CI: 1.03-2.44] and children who do not enjoy being with family [OR=2.05, 95%CI: 1.00-4.18]. Additional analysis showed that situations such as parents' frequent use of mobile phones during talking, family members' frequent use of mobile phones even during family time, and not enjoying being with family were associated with not setting rules for children's use of mobile phones and personal computers at home.Conclusion　Our findings suggest that factors such as ownership of devices and the ways parents use their mobile phones are associated with children's hours of internet use at home. To create an environment where children use internet appropriately, parental practices regarding mobile device use and rule setting at home may be important.

National data showed that delayed sleep in six-year-old children was associated with excessive use of electronic devices at 12 years.

AIM: Cross-sectional studies have shown associations between adolescent sleep problems and the use of electronic devices, such as mobile phones, but longitudinal studies remain scarce. We explored any association between delayed bedtimes at six years old and the excessive use of electronic devices at 12 years of age. Texting was a prime focus. METHODS: We analysed 9607 adolescents who owned mobile phones in 2013 using the Japanese Longitudinal Survey of Newborns in the 21st Century, which started in 2001. The outcomes were daily excessive use of a mobile phone, television (TV) and video games. RESULTS: Delayed bedtime at the age of six years was associated with excessive texting at weekends. The adjusted odds ratios and 95% confidence intervals obtained from logistic regression analyses were 1.88 (1.14-3.10) for the 10-11 pm group and 1.98 (1.08-3.63) for the after 11 pm group, compared with the before 9 pm group. Later bedtimes were also associated with increased risks of excessive TV viewing and video game use. CONCLUSION: Our study indicated that six-year-olds who regularly stayed up late at night used electronic devices more frequently, or for longer, at the age of 12. Parents need to be more aware of links between sleep issues and electronic devices.

Impact of maternal and paternal smoking on birth outcomes.

Background: The adverse effects of maternal and paternal smoking on child health have been studied. However, few studies demonstrate the interaction effects of maternal/paternal smoking, and birth outcomes other than birth weight have not been evaluated. The present study examined individual effects of maternal/paternal smoking and their interactions on birth outcomes. Methods: A follow-up hospital-based study from pregnancy to delivery was conducted from 1997 to 2010 with parents and newborn infants who delivered at a large hospital in Hamamatsu, Japan. The relationships between smoking and growth were evaluated with logistic regression. Results: The individual effects of maternal smoking are related to low birth weight (LBW), short birth length and small head circumference. The individual effects of paternal smoking are related to short birth length and small head circumference. In the adjusted model, both parents' smoking showed clear associations with LBW (odds ratio [OR] = 1.64, 95% confidence interval [CI] 1.18-2.27) and short birth length (-1 standard deviation [SD] OR = 1.38, 95% CI 1.07-1.79; -2 SD OR = 2.75, 95% CI 1.84-4.10). Conclusions: Maternal smoking was significantly associated with birth weight and length, but paternal smoking was not. However, if both parents smoked, the risk of shorter birth length increased.

Children's Media Use and Self-Regulation Behavior: Longitudinal Associations in a Nationwide Japanese Study.

Objective The effect of media use on child behavior has long been a concern. Although studies have shown robust cross-sectional relations between TV viewing and child behavior, longitudinal studies remain scarce. Methods We analyzed the Longitudinal Survey of Babies, conducted by Japan's Ministry of Health, Labour and Welfare since 2001. Among 53,575 families, 47,010 responded to the baseline survey; they were followed up every year for 8 years. Complete data were available for longitudinal analysis among 32,439 participants. Daily media use (TV viewing and video game-playing hours at ages 3, 4, and 5 years) was used as the main exposure. We employed an index of the children's self-regulatory behavior as the outcome variable. Odds ratios and 95 % confidence intervals (CIs) were estimated. Results Among boys, longer TV-viewing times at ages 4 and 5 were related to problematic self-regulatory behavior. Compared with boys who watched just 1-2 h of TV a day, those who watched it 4-5 h had a 1.79-fold greater risk (CI 1.22-2.64) of problematic self-regulatory behavior, according to parental report. Among girls, similar results were evident at ages 4 and 5 (e.g., adjusted odds ratios for 4-5 h daily viewing versus 1-2 h at age 4: 2.59; 95 % CI 1.59-4.22). Video games may have a protective effect on the risk of problematic self-regulatory behavior at ages 3 and 5. Conclusion Longer daily exposure to TV during early childhood (age 4-5) may be associated with subsequent problematic child self-regulatory behavior.

Association between Short Maternal Height and Low Birth Weight: a Hospital-based Study in Japan.

Anthropometry measurements, such as height and weight, have recently been used to predict poorer birth outcomes. However, the relationship between maternal height and birth outcomes remains unclear. We examined the effect of shorter maternal height on low birth weight (LBW) among 17,150 pairs of Japanese mothers and newborns. Data for this analysis were collected from newborns who were delivered at a large hospital in Japan. Maternal height was the exposure variable, and LBW and admission to the neonatal intensive care unit were the outcome variables. Logistic regression models were used to estimate the associations. The shortest maternal height quartile (131.0-151.9 cm) was related to LBW (OR 1.91 [95% CI 1.64, 2.22]). The groups with the second (152.0-157.9 cm) and the third shortest maternal height quartiles (158.0-160.9 cm) were also related to LBW. A P trend with one quartile change also showed a significant relationship. The relationship between maternal height and NICU admission disappeared when the statistical model was adjusted for LBW. A newborn's small size was one factor in the relationship between shorter maternal height and NICU admission. In developed countries, shorter mothers provide a useful prenatal target to anticipate and plan for LBW newborns and NICU admission.

Breast-feeding and hospitalization for asthma in early childhood: a nationwide longitudinal survey in Japan.

OBJECTIVE: Whether or not breast-feeding is protective against asthma among children is still controversial. Therefore, we examined the effects of breast-feeding on hospitalization for asthma in early childhood. DESIGN: Secondary data analyses of a nationwide longitudinal survey of children in Japan ongoing since 2001, with results collected from 2001 to 2004. We used logistic regression models to evaluate the associations of breast-feeding with hospitalization for asthma in children between the ages of 6 and 42 months, adjusting for children's factors (sex, day-care attendance and presence of older siblings) and maternal factors (educational attainment and smoking habit). Setting All over Japan. SUBJECTS: Term singleton children with information on feeding practices during infancy (n 43367). RESULTS: After adjusting for maternal factors and children's factors, exclusive breast-feeding at 6-7 months of age was associated with decreased risk of hospitalization for asthma in children. The adjusted odds ratio was 0.77 (95% CI 0.56, 1.06). One-month longer duration of breast-feeding was associated with a 4% decreased risk of hospitalization for asthma (OR = 0.96; 95% CI 0.92, 0.99). CONCLUSIONS: The protective effects of breast-feeding on hospitalization for asthma were observed in children between the ages of 6 and 42 months.

Long-Term Effects of Breastfeeding on Children's Hospitalization for Respiratory Tract Infections and Diarrhea in Early Childhood in Japan.

Whether or not the protective effects of breastfeeding last during or after a shift to a weaning diet is not clear. In the present study, we examined the effects of breastfeeding on hospitalization for respiratory tract infections and diarrhea in early childhood in Japan. Data were extracted from a nationwide longitudinal survey of Japanese children. We restricted the study participants to singleton children who were born after 37 gestational weeks and whose information on feeding practice during infancy were included (n = 43,367). We used logistic regression models to evaluate the associations of breastfeeding with hospitalization for the two diseases among young children (i.e., between ages 6 and 18 months, between ages 18 and 30 months, and between ages 30 and 42 months, respectively), adjusting for children's factors (sex, birth weight, childcare attendance and presence of siblings) and maternal factors (educational attainment and smoking status). Breastfeeding compared with infant formula was not associated with reduced risk of hospitalization for diarrhea during the periods we examined. Although breastfeeding was not associated with reduced risk of hospitalization for respiratory tract infections between ages 6 and 18 months, breastfeeding showed protective effects after that period: the adjusted odds ratios (95% confidence intervals) of exclusive breastfeeding were 0.82 (0.66-1.01) between ages 18 and 30 months and 0.76 (0.58-0.99) between ages 30 and 42 months. Breastfeeding may have long-term protective effects on hospitalization for respiratory tract infections after infancy, but not for diarrhea.

Breastfeeding and behavioral development: a nationwide longitudinal survey in Japan.

OBJECTIVE: To prospectively examine the prolonged effect of breastfeeding on behavioral development. STUDY DESIGN: We used a large, nationwide Japanese population-based longitudinal survey that began in 2001. We restricted participants to term singletons with birth weight >2500 g (n = 41 188). Infant feeding practice was queried at age 6-7 months. Responses to survey questions about age-appropriate behaviors at age 2.5 and 5.5 years were used as indicators of behavioral development. We conducted logistic regression analyses, controlling for potential child and parental confounding factors, with formula feeding as the reference group. RESULTS: We observed a dose-response relationship between breastfeeding status and an inability to perform age-appropriate behaviors at both ages. With a single exception, all ORs for outcomes for exclusive breastfeeding were smaller than those for partial feeding of various durations. The protective associations did not change after adjustment for an extensive list of confounders or in the sensitivity analyses. CONCLUSION: We observed prolonged protective effects of breastfeeding on developmental behavior skills surveyed at age 2.5 and 5.5 years. Beneficial effects were most likely in children who were breastfed exclusively, but whether a biological ingredient in breast milk or extensive interactions through breastfeeding, or both, is beneficial is unclear.