Parental stress and food allergy phenotypes in young children: A National Birth Cohort (JECS).

BACKGROUND: Food allergy children and their families tend to have emotional distress and anxiety. There have been few reports of differences in parenting stress and a child's food allergy phenotypes. METHODS: We examined the associations between food allergy phenotypes in children and parenting stress assessed by the Parenting Stress Index-Short Form (PSI-SF) from a national birth cohort (Japan Environment and Children's Study). RESULTS: We included 65,805 children for statistical analysis. Of them, 7.2% of children had a food allergy diagnosis at 2 years old. The means of the total PSI-SF (39.9 ± 10.3, 39.1 ± 9.9), CD-SF (19.5 ± 5.4, 19.1 ± 5.2), and PD-SF (20.5 ± 6.3, 20.0 ± 6.1) scores are similar for caregivers in the with and without food allergy groups. Food allergy diagnosis resulted in significantly higher total PSI scores (coefficient .47, 95% CI 0.19-0.75, p = .001), CD-SF (coefficient .22, 95% CI 0.07-0.38, p = .004), and PD-SF (coefficient .24, 95% CI 0.08-0.41, p = .004). A similar trend was observed for allergy reactions to hen's egg. However, there was no clear relationship between allergic reactions to milk, wheat, nuts, and PSI-SF. CONCLUSIONS: Parental stress was significantly related to a child's food allergy. Furthermore, hen's egg allergy increased parental stress. Multiple food avoidance might also increase parental stress. Healthcare providers need to be aware of parental stress in our daily clinic.

Teenage and young adult pregnancy and depression: findings from the Japan environment and children's study.

Teenage pregnancy increases the threat of depression because of its many factors. Pregnancy during young adulthood may also have several risk factors for depression compared to older pregnancies. However, data on depression in young adult pregnancies are lacking. This study investigated the association between teenage and young adult pregnancy and depression. Data from the Japan Environment and Children's study was used as a nationwide multicenter prospective cohort study. A multivariate logistic regression was performed to investigate the association between age groups (14-19, 20-24, 25-29, 30-34, ≥ 35 years) and depression, adjusted for behavioral and sociodemographic characteristics. Depression was assessed using the Kessler Psychological Distress Scale. In total, 96,808 pregnant women responded to the questionnaire. Teenage (14-19 years) and young adult (20-24 years) pregnancy were associated with an increased risk of depression compared to older pregnancy (≥ 35 years) (teenage: OR 4.28, 95% confidence interval, CI [3.24-5.64]; young adult: OR 3.00, 95% CI [2.64-3.41]). After adjusting for covariates, the magnitude of the risk of depression was attenuated. However, teenage and young adult pregnancy remained at a significantly increased risk of depression compared to older pregnancy (teenage: OR 2.38, 95% CI [1.77-3.21]; young adult: OR 2.14, 95% CI [1.87-2.46]). Our findings indicate that teenage and young adults' pregnancy are at an increased risk of depression compared to older pregnancy. These findings suggest prioritizing teenage and young pregnant women for prevention and interventions related to depression.

Congenital hypothyroidism and thyroid function in a Japanese birth cohort: data from The Japan Environment and Children's Study.

The most common hormonal and metabolic disease in early childhood is congenital hypothyroidism (CH). This study aimed to describe CH in large-scale birth cohort data and summarize the results of serum thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels in 2-yr-old children. Data were obtained from the Japan Environment and Children's Study (JECS), and we identified 171 children with CH detected in newborn screenings or medical records (170.5 per 100,000 population). Infants with CH are at higher risk of developing congenital diseases than those without CH. Of 171 children with CH, 20 (11.7%) were diagnosed with congenital heart defects, 33 (19.3%) had chromosomal or other congenital abnormalities, and 23 (13.5%) had Down syndrome. At the age of 2 yr old, the median and 95% reference range values for TSH and fT4 were 2.13 (0.78-5.52) µIU/mL and 1.2 (1.0-1.5) ng/dL, respectively. Moreover, boys had slightly higher TSH and fT4 levels than did girls. Data on the distribution of TSH and fT4 in 2-yr-old children should be useful for decreasing the misclassification of thyroid disorders in the pediatric population. Trial-off treatment and re-evaluation of thyroid function are needed to classify permanent congenital hypothyroidism and transient congenital hypothyroidism after 3 yr of age.

Sex steroid hormones and allergic diseases in children: a pilot birth cohort study in the Japan Environment and Children's Study cohort.

BACKGROUND: Numerous studies suggest that sex steroids might play a role in sex disparity observed in allergic diseases in adults. However, whether sex hormones influence allergic diseases in children remains unclear. The aim of the present study was to examine the association of sex steroid hormones with allergic disease in Japanese children. METHODS: The present cross-sectional study included 145 6-year-old children participating in a pilot birth cohort study in the Japan Environment and Children's Study. Data on allergic diseases were obtained from questionnaires, and serum levels of sex steroid hormones and allergen-specific IgE were measured. Logistic regression was performed to evaluate the association of sex hormones with allergic diseases. RESULTS: After adjusted sex, amount of body fat at 6 years, parental history of allergic disease, and exposure to tobacco smoke, serum dehydroepiandrosterone sulfate level was significantly associated with reduced odds of any allergic disease (adjusted odds ratio, 0.58; 95% confidence interval, 0.36-0.93; P = 0.024) and serum follicle-stimulating hormone level was significantly associated with increased odds of any allergic disease (adjusted odds ratio, 2.04; 95% confidence interval, 1.01-4.11, P = 0.046). Dehydroepiandrosterone sulfate level showed a significant association with number of allergic diseases. CONCLUSIONS: The current study findings suggest that sex hormones may play an important role in the development of allergic diseases in prepubertal children.

Health-related quality of life of mothers and developmental characteristics of very low birth weight children at 2.5 years of age: results from the Japan Environment and Children's Study (JECS).

BACKGROUND: The level of child development may be associated with the risk of poor maternal health-related quality of life (HRQoL). The objective of this study was to describe the developmental characteristics of very low birth weight (VLBW) children at 2.5 years of age and to examine associations between maternal HRQoL and the degree of child development based on the Japanese version of Ages and Stages Questionnaire (J-ASQ-3). METHODS: A cross-sectional study was performed using the data from a nationwide prospective birth cohort study in Japan. Among a total of 104,062 fetal records, the VLBW infants (birth weight ≤ 1500 g) were analyzed using linear regression models, adjusted for potential covariates. Subgroup analysis was also conducted to assess the association between social connection or cooperation of the partner and maternal HRQoL by the level of child development. RESULTS: The final study subjects included 357 VLBW children and mothers. The suspected developmental delays (SDDs) in at least two domains was significantly associated with lower maternal mental HRQoL regression coefficient -2.314 (95%CI: -4.065 to -0.564). There was no association between the status of child development and maternal physical HRQoL. After adjusting for child and maternal covariates, the maternal HRQoL was not significantly associated with child development. Amongst women who indicated having some social support, having a child with a SDD in two or more domains was negatively associated with mental HRQoL compared with women whose child was less developmental delay, regression coefficient -2.337 (95%CI: -3.961 to -0.714). Amongst women who indicated having partner's cooperation to child-rearing, having a child with a SDD in two or more domains was negatively associated with mental HRQoL compared with women whose child was less developmental delay, regression coefficient -3.785 (95%CI: -6.647 to -0.924). CONCLUSIONS: Our findings indicate that the lower maternal mental HRQoL was independently associated with the SDDs evaluated by the J-ASQ-3, whereas there was no association after adjusting for covariates. Further research is warranted to elucidate the impact of social connection and partner's cooperation on maternal HRQoL and child development. This study urges that particular attention should be paid to mothers of VLBW children with SDDs and also to provide early intervention and continued support.

Reference blood pressure values obtained using the auscultation method for 2-year-old Japanese children: from the Japan Environment and Children's Study.

BACKGROUND: Reference blood pressure (BP) values for Japanese children based on a large number of measurements by auscultation have not yet been established. METHODS: This was a cross-sectional analysis of data from a birth-cohort study. The data from the sub-cohort study conducted for children at the age of 2 years in the Japan Environment and Children's Study from April 2015 to January 2017 were analyzed. BP was measured via auscultation using an aneroid sphygmomanometer. Each participant was measured in triplicate, and the average value of two consecutive measurements with a difference of less than 5 mmHg was recorded. The reference BP values were estimated using the lambda-mu-sigma (LMS) method and compared with those obtained via the polynomial regression model. RESULTS: Data from 3361 participants were analyzed. Although the difference between the estimated BP values by the LMS and the polynomial regression model was small, the LMS model was more valid based on the results of the fit curve of the observed values and regression models for each model. For 2-year-old children with heights in the 50th percentile, the 50th, 90th, 95th, and 99th percentile reference values of systolic BP (mmHg) for boys were 91, 102, 106, and 112, and that for girls were 90, 101, 103, and 109, respectively, and those of diastolic BP for boys were 52, 62, 65, and 71, and that for girls were 52, 62, 65, and 71, respectively. CONCLUSION: The reference BP values for 2-year-old Japanese children were determined based on auscultation and were made available.

Maternal Dietary Zinc Intake during Pregnancy and Childhood Allergic Diseases up to Four Years: The Japan Environment and Children's Study.

Maternal dietary zinc intake and childhood allergy have inconsistent relationships. Thus, this study aimed to evaluate the influence of low maternal dietary zinc intake during pregnancy on developing pediatric allergic diseases. This study was designed using the Japan Environment and Children's Study dataset. The model building used data from 74,948 mother-child pairs. Maternal dietary zinc intake was estimated based on the food frequency questionnaire, collecting the intake information of 171 food and beverage items. Fitted logistic regression models and generalized estimating equation models (GEEs) estimated the association between energy-adjusted zinc intake and childhood allergic conditions. The energy-adjusted zinc intake did not affect the risk of developing allergic disorders (wheeze, asthma, atopic dermatitis, rhinitis, and food allergy) in offspring. The GEE model revealed similar insignificant odds ratios. No significant association was found between zinc intake during pregnancy and allergic diseases in offspring in early childhood. Further study remains necessary to examine the association between zinc and allergy with reliable zinc status biomarkers in the body.

Association between pre-pregnancy weight status and dietary patterns during pregnancy: results from the Japan Environment and Children's Study.

OBJECTIVE: Pre-pregnancy weight status is related to offspring health and may influence dietary patterns during pregnancy. We aimed to evaluate the link between pre-pregnancy weight status and dietary patterns during pregnancy. DESIGN: Dietary data were collected using a FFQ during middle or late pregnancy. Dietary patterns were identified using principal component analysis. Anthropometric data were extracted from medical charts. Multiple linear regression was used to assess associations between pre-pregnancy weight status (severely or moderately underweight, mildly underweight, normal weight, overweight and obese) and dietary patterns during pregnancy after adjusting for socio-demographic characteristics. SETTING: Nationwide Japan. PARTICIPANTS: Pregnant Japanese women enrolled in the Japan Environment and Children's Study, a prospective birth cohort study (n 90 765). RESULTS: We identified three dietary patterns. Compared with women with pre-pregnancy normal weight, those with pre-pregnancy obesity were less likely to habitually consume 'fruits and vegetables' pattern (coefficient, -0·18; 95 % CI, -0·21, -0·14) and 'confectionery' pattern (coefficient, -0·18; 95 % CI, -0·21, -0·14) and more likely to consume 'white rice and soy products' pattern (coefficient, 0·08; 95 % CI, 0·04, 0·11), and those with severely or moderately pre-pregnancy underweight were more likely to consume 'confectionery' pattern (coefficient, 0·06; 95 % CI, 0·03, 0·09) during pregnancy, after adjusting for confounders. CONCLUSION: We found that moderately and severely pre-pregnancy underweight women and those with obesity had unhealthy dietary patterns compared to those with pre-pregnancy normal weight. Our findings suggest that prenatal dietary advice is important and should be based on the pre-pregnancy weight status.

Comparison of physician- and self-assessed pubertal onset in Japanese children.

Introduction: Physical examinations to assess pubertal development are challenging in large epidemiological surveys. This study aimed to assess the reliability of judgment of pubertal onset in Japanese children by the original pubertal self-assessment sheet. Methods: A total of 144 children aged 10 or 12 years were recruited between March 2019 and September 2020 from the pediatric endocrine outpatient clinics of participating institutions. Agreement between the physician- and participantassessed pubertal onsets was determined using unweighted kappa (UK) and Gwet's agreement coefficient (AC1). Results: The physician's assessment of pubertal onset was in slight agreement with that of the self-assessment sheet in 10-year-old boys (UK: 0.23 and AC1: 0.14), whereas the agreement between the physician's assessment and self-assessment sheet results was good and the physician's assessment was fair (UK: 0.64 and AC1: 0.94) in 12-year-old boys. The physician's assessment of pubertal onset were in good and moderate agreement with the self-assessment sheet in 10-year-old girls (UK/AC1: 0.74/0.78, respectively). In 12-year-old girls, although it showed poor agreement with UK (0.46), there was a very good agreement with AC1 (0.88). Conclusions: Although self-assessment of breast development was in good agreement with that of the physician's assessment for determining pubertal onset in girls, large-scale epidemiological studies are difficult to conduct for adolescent boys, especially for those in the early pubertal stage.

Relationship between Food Allergy and Endotoxin Concentration and the Toleration Status at 2 Years: The Japan Environment and Children's Study.

Changes in household endotoxin concentration may affect the prognosis of food allergy (FA), but data on the association between household endotoxin concentration and an already-developed FA are scarce. Thus, we investigated the association between environmental endotoxin exposure and tolerance to hen's egg (HE) and cow's milk (CM) using data from children participating in the Japan Environment and Children's Study who had HE allergies (n = 204) and CM allergy (n = 72) in their first year of life. We grouped the endotoxin results into quartiles 1-4 (Q1-Q4). In children with HE allergy and with CM allergy, there was no significant difference in the prevalence of tolerance to HE and CM at 2 years old when comparing endotoxin levels of the children in Q1 with those in Q2, Q3, and Q4, respectively. However, subgroup analyses by the presence of eczema and causal foods revealed that children in Q1 had a lower prevalence of tolerance to foods in some subgroup analyses and lower causal allergen-specific immunoglobulin G4 levels. Although an individually based approach against endotoxin according to background characteristics, such as eczema and causal foods, is necessary, preventing excessive endotoxin removal might contribute to FA resolution in some children.

Endotoxin concentration and persistent eczema in early childhood.

Although endotoxin concentration in the environment is negatively associated with atopic dermatitis (AD) onset in early childhood, the association between endotoxin concentration in the environment and eczema resolution in children with preexisting eczema is unclear. The aim of this study was to evaluate the association between endotoxin concentration in house dust and eczema persistence in young children. The authors used data from children participating in JECS (Japan Environment and Children's Study). In children who had AD or AD-like lesions at the age of 1 year, the authors investigated the association between the prevalence of eczema at the age of 3 years and endotoxin concentration (categorized by quartiles) in the dust on children's mattresses at the ages of 1.5 and 3 years. This study included 605 children. Eczema was significantly less prevalent among children whose mattresses were in the second and third quartiles of endotoxin concentration when they were 18 months old than among children whose mattresses were in the first quartile (adjusted odds ratio, 0.57 [95% confidence interval, 0.35-0.93] and adjusted odds ratio, 0.49 [95% confidence interval, 0.29-0.83], respectively). Moreover, of the children with eczema at age 3 years, those whose mattresses had endotoxin concentrations in the first quartile had significantly worse sleep disturbance caused by itchy rash (>1 time per week) than did those whose mattresses were in the third and fourth quartiles (20.0% vs 3.3% and 3.7%, both p values < 0.01). The findings indicate that low endotoxin exposure is associated with a higher prevalence of persistent eczema during early childhood.

How a Family History of Allergic Diseases Influences Food Allergy in Children: The Japan Environment and Children's Study.

The influence of family allergic history on food allergy in offspring in Japan is unknown. We analyzed data from a nationwide birth cohort study using logistic regression models to examine the associations of maternal, paternal, and both parental histories of allergic diseases (food allergy, atopic dermatitis, asthma, and rhinitis) with their child's food allergy at 1.5 and 3 years of age. This analysis included 69,379 singleton full-term mothers and 37,179 fathers and their children. All parental histories of allergic diseases showed significant positive associations with their child's food allergy. When both parents had a history of allergic diseases, the adjusted odds ratio (aOR) tended to be higher than when either parent had allergic diseases (p for trend < 0.0001). The highest aOR was detected when both parents had food allergy (2.60; 95% confidential interval, 1.58−4.27), and the aOR was 1.71 when either parent had food allergy (95% confidential interval, 1.54−1.91). The aORs were attenuated but still had significant positive associations after adjusting for the child's atopic dermatitis, a risk factor for allergy development. In conclusion, all parental allergic diseases were significantly positively associated with their child's food allergy. The effect of family history showed a stepwise increase in risk from either parent to both parents, and the highest risk of allergic disease was a parental history of food allergy.

Allergic Disorders and Risk of Anemia in Japanese Children: Findings from the Japan Environment and Children's Study.

Previous epidemiological studies have reported an increased risk of anemia in people with allergic disorders. However, previous studies have followed a cross-sectional design. The aim of this study was to investigate the association between the two conditions with a cohort dataset. We used data of 80,943 children in the Japan Environment and Children's Study, the largest birth cohort in Japan. The association between anemia and allergic disorders was evaluated with a logistic regression model and propensity score analysis. After adjusting for potential confounders, children with asthma (odds ratio [OR], 1.85; 95% confidence interval [CI], 1.32-2.60), atopic dermatitis (OR, 2.18; 95% CI, 1.66-2.85), allergic rhinitis (OR, 1.35; 95% CI, 1.05-1.74), allergic rhinoconjunctivitis (OR, 2.95; 95% CI, 1.91-4.54), and food allergies (OR, 1.92; 95% CI, 1.44-2.56) at 2 years of age predicted high odds of developing anemia in the next year. Any allergy at 2 years of age was associated with an increased risk of anemia at the age of 3 years (OR, 1.80; 95% CI, 1.41-2.29). The findings remained stable in the propensity score analysis. Results suggest that allergic diseases were related to caregiver-reported anemia in children.

Smoking Exposure Is Associated with Serum Vitamin D Deficiency in Children: Evidence from the Japan Environment and Children's Study.

Tobacco smoke exposure is known to lower serum 25-hydroxyvitamin D (25(OH)D) concentrations. This study evaluated the association between passive smoking and vitamin D deficiency (VDD) in young children using data from the Japan Environment and Children's Study (JECS), the largest birth cohort study in Japan. Information on parental smoking status was extracted from a survey of JECS for children aged 1.5 years and data for serum 25(OH)D concentrations were obtained from blood tests in the Sub-Cohort Study of JECS performed at age 2 years. Logistic regression and linear models were fitted to evaluate the association between these variables. Data were analyzed for 4593 children. After adjusting for covariates, smoke exposure was significantly associated with increased incidence of VDD (OR 1.35; 95% CI, 1.14-1.59) according to the logistic model. The linear model indicated that passive smoking negatively predicted de-seasonalized serum 25(OH)D concentrations (ß -0.5; 95% CI -0.95 to -0.08) in children aged 2 years. The results suggest that smoke exposure is a risk factor for VDD in children. Given that VD plays a crucial role in bone metabolism and the immune system, our findings are significant for clinical and public health.

Persistent eczema leads to both impaired growth and food allergy: JECS birth cohort.

Skin inflammation leads to altered cytokine/chemokine production and causes systemic inflammation. The systemic mechanism of atopic dermatitis (AD) is recognized to affect systemic metabolism. This study aimed to examine the relationship between early-onset persistent eczema and body weight, height, and body mass index (BMI), in addition to food allergy in a birth cohort among infants. This study design was a nationwide, multicenter, prospective birth cohort study-the Japan Environment and Children's Study (JECS). Generalized linear models were fitted for z scores of weight, height, BMI, and food allergy to evaluate the relationship between eczema and these outcomes for infants at age1, 2, and 3 years. Persistent eczema was negatively associated with height at the age of 2 years (estimated coefficient, -0.127; 95% confidence interval [CI], -0.16 to -0.095) and 3 years (-0.177; 95% CI, -0.214 to -0.139). The same tendency was also observed with weight and BMI. Early disease onset at younger than 1 year and persistent eczema had the strongest association with development of food allergy at age 3 years (OR, 11.794; 95% CI, 10.721-12.975). One phenotype of eczema with early-onset and persistent disease creates a risk of both physical growth impairment and development of food allergy. Infants who present with the early-onset and persistent type of eczema should be carefully evaluated daily for impaired physical growth and development of food allergy.

25-Hydroxyvitamin D levels among 2-year-old children: findings from the Japan environment and Children's study (JECS).

BACKGROUND: The study aim was to obtain epidemiological data on vitamin D levels for the pediatric population in Japan. We assessed the prevalence of vitamin D deficiency and insufficiency in 2-year-old Japanese children using data from a large ongoing birth cohort study. METHODS: Data for analysis was obtained from the Japan Environment and Children's Study (JECS) and a Sub-Cohort Study (SCS) of JECS. We evaluated the children's serum 25(OH) D levels by 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles, and the rates of vitamin D deficiency or insufficiency. We also presented a weighted prevalence rate for vitamin D deficiency or insufficiency among all children in JECS. RESULTS: After excluding children with missing 25(OH)D2 or 25(OH)D3 data, we analyzed 4655 remaining children, of whom 24.7% (95% CI, 23.5-26.0%) had vitamin D deficiency (< 20 ng/mL), and 51.3% (95% CI, 49.8-52.7%) were at risk of vitamin D insufficiency (20-30 ng/mL). The estimated prevalence of vitamin D deficiency and insufficiency among all children in JECS were 25.4% (95% CI, 24.1-26.7%) and 50.9% (95% CI, 49.4-52.4%). Vitamin D deficiency was found in 22.9% of boys and 26.5% of girls. Median serum 25(OH) D concentrations were lower among participants measured during winter and spring than among those measured in summer and autumn. The highest rate of vitamin D deficiency was observed in Hokkaido, the northernmost prefecture of Japan. CONCLUSION: We analyzed data on serum 25(OH) D levels from a birth cohort study and found that vitamin D deficiency and insufficiency are very common among 2-year-old Japanese children. Sex, season, and latitude affect serum 25(OH) D concentrations.

Hypertensive disorders of pregnancy and risk of allergic conditions in children: Findings from the Japan Environment and Children's study (JECS).

BACKGROUND: Hypertensive disorders of pregnancy (HDP) are one of the most common medical conditions that women encounter during pregnancy. Whether or not hypertensive disorders of pregnancy (HDP) are associated with allergic conditions in the offspring is unclear. This study used data from a large Japanese birth cohort to investigate whether HDP contributes to the development of allergic conditions in the offspring at 3 years. We also assessed the effect of blood pressure at different pregnancy trimesters on children's allergies. METHODS: We obtained data from the Japan Environment and Children's Study (JECS), which included 104 062 fetal records. After data selection, we analyzed 77 505 mother-child pairs, using logistic regression models to examine the relationships between HDP or the mother's blood pressure and their children's allergic conditions. In addition, we also evaluated the effect of HDP during pregnancy on allergies with a propensity score matched dataset, using a logistic regression model that predicts the conditional probability of whether a mother belonged to the HDP or non-HDP group. RESULTS: Among the 77 505 mothers eligible for analysis, 2334 (3.0%) had HDP. Percentages of women with hypertension were 1.7% in early gestation, 1.0% in mid-gestation, and 1.6% in late gestation. After adjusting for multiple potential confounders, HDP contributed nothing to allergy development in offspring. Children born to women with hypertension were no more likely than those without to have allergic conditions at 3 years of age. The propensity score matched dataset showed similar findings. CONCLUSION: HDP and high blood pressure during pregnancy are apparently not risk factors for developing allergy in offspring. This information may help clinicians in counseling women who suffered HDP during pregnancy.

Serum 25-Hydroxyvitamin D Concentrations and Atopic Dermatitis in Early Childhood: Findings from the Japan Environment and Children's Study.

Vitamin D (VitD) may affect immune system modulation and result in the development of atopic dermatitis (AD). However, published findings have remained controversial. We investigated the association between early-life 25-hydroxyvitamin D (25(OH)D) levels and AD risk at childhood with a birth cohort. The data were obtained from "the Japan Environment and Children's Study (JECS)" and "the Sub-Cohort study of JECS" performed with children aged 2 years. "Liquid chromatography-tandem mass spectrometry" was used to measure VitD. The information on AD was obtained from parents' answers to a questionnaire when their children were aged 3 years. In order to explain the seasonal effects on VitD levels, a deseasonalized continuous variable was further calculated. The logistic regression models were fitted to evaluate the effect of VitD on childhood AD. The study included 4378 children with complete data on VitD and AD. The results from models indicated that low VitD at 2 years was not a risk factor for the development of AD at 3 years, after adjusting for potential confounders. Moreover, there was no U-shape relationship between deseasonalized VitD and childhood AD. Overall, early-life 25(OH)D levels were not link to the increased risk of developing childhood AD.

Association of Hemoglobin and Hematocrit Levels during Pregnancy and Maternal Dietary Iron Intake with Allergic Diseases in Children: The Japan Environment and Children's Study (JECS).

Few epidemiologic studies have examined the role of maternal iron status in allergic diseases in offspring and findings have been inconsistent. We used a large birth cohort in Japan to explore the association of the markers for maternal iron status (maternal hemoglobin, hematocrit and dietary iron intake during pregnancy) with allergy development in offspring during early childhood. We analyzed information on children age 0-3 years from the Japan Environment and Children's Study (JECS). We used logistic models and generalized estimating equation models to evaluate the effect of maternal hemoglobin and hematocrit levels and dietary iron intake on allergies in children. Models were also fitted with propensity score-matched datasets. Data were collected for a total of 91,247 mother-child pairs. The prevalence (95% confidence interval) of low hemoglobin and hematocrit was 14.0% (13.7-14.2%) and 12.5% (12.3-12.8%), respectively. After adjusting confounders, low hemoglobin and hematocrit during pregnancy were not associated with childhood allergic outcomes. Findings from models with propensity score-matched datasets also indicated that children born to mothers with low hemoglobin or hematocrit levels during pregnancy did not have a higher risk of developing allergic conditions at 3 years old. We found no meaningful associations between low energy adjusted maternal dietary iron intake and allergies in children. In conclusion, using birth cohort data, we found no evidence supporting an association of low maternal hemoglobin, hematocrit and low dietary iron intake with allergy symptoms during early childhood. Further studies with more suitable proxy markers for blood iron status are needed.