Congenital Anomalies in Infants in Fukushima from 2011 to 2014: The Japan Environment and Children's Study

Introduction

This study aimed to assess congenital anomalies among infants from 2011 to 2014 in Fukushima and compare the assessment with that from other geographical regions in Japan.

Methods

We used the dataset of the Japan Environment and Children's Study (JECS), which is a nationwide prospective birth cohort study. For the JECS, participants were recruited through 15 regional centers (RC), including Fukushima. Pregnant women were recruited between January 2011 and March 2014. The Fukushima RC recruited all municipalities in the Fukushima Prefecture, from where we compared congenital anomalies in infants from the Fukushima RC to those in the infants from 14 other RCs. Crude and multivariate logistic regression analyses were also performed, with the multivariate logistic regression analysis being adjusted for maternal age, maternal body mass index (kg/m²), infertility treatment, multiple pregnancies, maternal smoking, maternal alcohol consumption, pregnancy complications, maternal infection, and infant sex.

Results

In the Fukushima RC, 12,958 infants were analyzed, and 324 infants were diagnosed with major anomalies (2.50%). In the remaining 14 RCs, 88,771 infants were analyzed and 2,671 infants were diagnosed with major anomalies (3.01%). Crude logistic regression analysis demonstrated that the odds ratio for the Fukushima RC was 0.827 (95% confidence interval, 0.736-0.929) using the other 14 RCs as a reference. Multivariate logistic regression analysis also demonstrated that the adjusted odds ratio was 0.852 (95% confidence interval, 0.757-0.958).

Conclusions

Fukushima Prefecture was found not to be an area at high risk for the occurrence of congenital anomalies in infants compared nationwide in Japan from 2011 to 2014.

Population attributable fraction of risk factors for low birth weight in the Japan Environment and Children's Study

BACKGROUND

Low birth weight (LBW), which is considered a birth weight of <2500  g, poses significant health problems for children. However, population attributable fraction (PAF) of risk factors for LBW have not been well studied.

OBJECTIVE

We aimed to re-evaluate associations between risk factors for LBW reported in previous studies that used the Japan Environment and Children's Study (JECS) data, and to estimate the magnitude of risk using PAF.

METHODS

Data including 91,559 mother-child dyads were obtained from JECS. Risk factors identified by previous studies that used JECS data were used to calculate odds ratios for LBW using a Bayesian logistic regression model. Based on calculated odds ratios, the PAF was calculated.

RESULTS

Parity, history of adenomyosis, hypertension disorder of pregnancy, maternal age at birth, prepregnancy body mass index, gestational weight gain (GWG), maternal smoking and lead (Pb) exposure were all significantly associated with LBW. The sum of the PAF of all factors was 79.4 %, with the largest PAF among single risk factors being GWG (16.5 %); the environmental portion of the PAF (Pb exposure, 14.6 % + maternal smoking, 12.1 %) surpassed the PAF of GWG.

CONCLUSION

Our findings suggest that the number of births classified as LBW can be reduced by approximately 27% if Pb exposure is reduced to the lowest quartile and maternal smoking is eliminated. Further investigations are needed to identify unknown risk factors for LBW.

Breastfeeding and risk of febrile seizures in the first 3 years of life: The Japan Environment and Children's Study

OBJECTIVE

Our study was conducted to examine the association between breastfeeding and febrile seizures (FS) in the first 3 years of life.

METHODS

We analyzed the dataset of the Japan Environment and Children's Study (JECS), which is a birth cohort study undertaken to elucidate the influence of environmental factors on children's health during the fetal period and early childhood. Information on feeding duration and feeding pattern, as well as information on febrile seizures, were obtained from questionnaires sent to mothers/caregivers. We categorized a child as having experienced FS if the child was reported as having been diagnosed with FS in the first 3 years. Modified Poisson regression with a robust error variance was used to estimate the effect of duration of breastfeeding and the risk of FS.

RESULTS

Of the 84,321 children included in the analysis, 6264 (7.4%) were reported to have experienced FS at least once in the first 3 years of life. Multivariate analyses showed that the risk of FS during the first 3 years of life tended to decrease as the duration of breastfeeding increased. Male sex and frequent fever episodes were also associated with an increased risk of FS.

CONCLUSIONS

Continued breastfeeding until 2 years of age, the most susceptible age for FS, had a small but protective effect on FS.

Early life exposure to indoor air pollutants and the risk of neurodevelopmental delays: The Japan Environment and Children's Study

Air pollution has been associated with childhood neurodevelopment. However, the role of indoor air pollution, especially volatile organic compounds (VOCs), on childhood neurodevelopment has been poorly explored to date. We investigated the association between indoor air pollutants and childhood neurodevelopment in 5,017 randomly selected children from the Japan Environment and Children's Study. When the participants reached 1.5 and 3 years of age, they were followed up with home visits and neurodevelopmental tests using the Ages and Stages Questionnaire (ASQ). At both ages, we collected indoor air samples for 1 week and measured 13 indoor air pollutants: particulate matter with an aerodynamic diameter of ≤2.5 μm, ozone, nitrogen dioxide, sulfur dioxide, and nine VOCs. The associations between air pollutants and ASQ scores were estimated using linear mixed effects models and weighted quantile sum regressions (WQS) at each age separately. Stratified analysis by sex was conducted. Exposure to m,p-xylene at the age of 3 was associated with lower communication, fine motor, and overall ASQ scores (coefficients: -0.18 [99% confidence intervals (CI): -0.35, -0.02], -0.23 [99 %CI: -0.43, -0.03], and - 0.72 [99 %CI: -1.41, -0.04] per 1 µg/m³ increase, respectively). Exposure to o-xylene at the age of 3 was associated with lower communication, gross motor, fine motor, and overall ASQ scores (coefficients: -0.48 [99 %CI: -0.90, -0.07], -0.45 [99 %CI: -0.78, -0.13], -0.65 [99 %CI: -1.14, -0.16], and -2.15 [99 %CI: -3.83, -0.47] per 1 µg/m³ increase, respectively). The WQS index was associated with lower gross motor ASQ scores at the age of 3 (coefficient: -0.27 [95 %CI: -0.51, -0.03] for one-unit WQS index increases), which was attributed to benzene (33.96%), toluene (26.02%), o-xylene (13.62%), and ethylbenzene (9.83%). Stratified analysis showed similar results. Although further investigations are required, our results suggest an association of neurodevelopmental delays with indoor low-level exposure to m,p-xylene and o-xylene in early life.

Breastfeeding and risk of febrile seizures in infants: The Japan Environment and Children's Study

OBJECTIVE

Our study was conducted to examine the association between breastfeeding and febrile seizures (FS) in the first year of life.

METHODS

We used data from a birth cohort study, the Japan Environment and Children's Study (JECS). In a self-administered questionnaire, we asked participants the duration of breastfeeding and whether their children were diagnosed as having FS during their first 12 months. We estimated the association of duration and exclusiveness of breastfeeding with the FS by using multiple logistic regression analysis.

RESULTS

Of 84,082 children, 995 (1.2%) were diagnosed as having FS by the age of 12 months. The prevalence of FS was higher in children who were breastfed for shorter duration. Multiple logistic regression analysis showed that, compared with children breastfed for less than 1 month, those breastfed for 4-6 months and 7-12 months had lower risks of FS (adjusted odds ratio [aOR], 0.65 [95% confidence interval {CI}, 0.42-0.99]; aOR, 0.66 [95% CI: 0.45-0.96], respectively). Moreover, compared with infants who received both breast milk and formula milk for 6 months, infants who were breastfed exclusively for 6 months had lower risk of FS (aOR: 0.78 [95% CI: 0.64-0.95]).

CONCLUSIONS

Our results suggest that breastfeeding has a protective effect against FS in the first year of life.