Associations of Birth Weight for Gestational Age with Child Health and Neurodevelopment among Term Infants: A Nationwide Japanese Population-Based Study.

OBJECTIVE: To examine the association of specific Z-score categories of birth weight for gestational age with child health and neurodevelopment using a large nationwide survey in Japan, focusing on term infants. STUDY DESIGN: We included 36 321 children born in 2010. Hospitalization up to 66 months of age was used as an indicator of health status, and responses to questions about age-appropriate behaviors at 30 and 66 months of age were used to indicate neurobehavioral development. We conducted binomial log-linear regression analyses, controlling for child and parental variables. A restricted cubic spline function was used to model the relationship. RESULTS: Compared with children with birth weight appropriate for gestational age (-1.28 to 1.28 SDs of expected birthweight for gestational age), children who were small for gestational age (SGA) (<-1.28 SD) had higher risks of hospitalization and unfavorable neurobehavioral development, and the risks increased as SGA status became more severe. Compared with the appropriate for gestational age group, the adjusted risk ratios for hospitalization for all causes were 2.5 (95% CI, 1.7-3.6), 1.3 (95% CI, 1.1-1.6), and 1.1 (95% CI, 1.0-1.2) for children who were severely, moderately, and mildly SGA and 1.0 (95% CI, 0.9-1.1), 1.1 (95% CI, 0.9-1.2), and 1.4 (95% CI, 0.9-2.1) for children who were mildly, moderately, and severely large for gestational age, respectively. Severely large for gestational age children also had higher risks of unfavorable neurobehavioral development. These results were supported by spline analyses. CONCLUSIONS: Among term infants, the risks of unfavorable child health and neurodevelopment increased with the severity of SGA.

Intrauterine and Early Postnatal Exposure to Particulate Air Pollution and Kawasaki Disease: A Nationwide Longitudinal Survey in Japan.

OBJECTIVES: To examine the effects of prenatal and postnatal exposure to particulate matter on Kawasaki disease (KD) occurrence, using data from a nationwide population-based longitudinal survey in Japan that began in 2010. STUDY DESIGN: Prenatal and postnatal suspended particulate matter concentrations were obtained at municipality level and assigned to participants based on their municipality of birth. We analyzed data from 30 367 participants with data on either exposure period. We used hospital admission for KD from 6 to 30 months of age as the main outcome of interest. We conducted a multilevel logistic regression analysis, adjusting for individual and municipality-level variables. RESULTS: Children who were exposed to higher levels of suspended particulate matter, in particular during pregnancy, were more likely to be hospitalized for KD. The ORs for ≥25 µg/m3 exposure compared with <20 µg/m3 exposure were 1.59 (95% CI 1.06, 2.38) for prenatal exposure and 1.41 (0.82, 2.41) for postnatal exposure. Prenatal exposure during mid-to-late gestation seemed to be more relevant for the increased risk. CONCLUSIONS: Early life exposure to particulate air pollution, in particular during pregnancy, is associated with an increased risk of KD hospital admission in early childhood in a nationally representative sample in Japan.

Catch-Up Growth and Neurobehavioral Development among Full-Term, Small-for-Gestational-Age Children: A Nationwide Japanese Population-Based Study.

OBJECTIVE: To examine the relationship between catch-up growth of full-term, small for gestational age (SGA) children and their neurobehavioral development. STUDY DESIGN: Data were obtained from a population-based nationwide Japanese longitudinal survey that started in 2001. Study participants were full-term children with information on height at 2 years of age (n = 32 533). Catch-up growth for SGA infants was defined as achieving a height at 2 years of age of more than -2.0 standard deviations for chronological age. Logistic regression analyses were used to estimate ORs and 95% CIs for the associations of SGA and catch-up growth status with neurobehavioral development at 2.5 and 8 years of age, adjusting for potential infant- and parent-related confounding factors. RESULTS: Fifteen percent of term SGA infants failed to catch up in height. At 2.5 years of age, SGA children without catch-up growth were more likely to be unable to climb stairs (OR, 10.42; 95% CI, 5.55-19.56) and unable to compose a 2-word sentence (OR, 3.58; 95% CI, 1.81-7.08) compared with children with normal growth at birth. Furthermore, SGA children without catch-up growth were at increased risk for aggressive behaviors (OR, 3.85; 95% CI, 1.19-12.47) at 8 years of age. CONCLUSIONS: Continuous follow-up for full-term SGA infants with failure of catch-up growth or poor postnatal growth may be beneficial for early detection and intervention for behavioral problems.

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.

Associations of preterm births with child health and development: Japanese population-based study.

OBJECTIVE: To examine associations between the duration of gestation and health and development outcomes at 2.5 years and 5.5 years using a Japanese population-based longitudinal survey (n = 47 015). STUDY DESIGN: Hospitalization was used as an indicator of physical health, and responses to questions about age-appropriate behaviors were used as an indicator of behavioral development. We conducted logistic regression analyses controlling for a set of neonatal and family factors. We also estimated population-attributable fractions. RESULTS: We observed a steady increase toward shorter duration of gestation in the risk of hospitalizations at age 2.5 years and 5.5 years and developmental delays at 2.5 years (Plinear trend < .001 for all outcomes). We found associations only between extremely preterm birth and delayed behavioral development at age 5.5 years. CONCLUSION: There is a linear relationship between shorter duration of gestation and increased risk of later health and developmental problems. In line with Rose's "population paradox," the population-attributable risks for these problems are greater for moderately preterm infants compared with extremely preterm infants.