Vitamin D deficiency is associated with numerous public health issues. Limited data are available for children in southern China, a region that receives abundant sunlight. We aimed to estimate the 25-hydroxyvitamin D (25(OH)D) levels in children in that area, and to determine seasonal variations in serum 25(OH)D levels. A total of 16,755 children aged 0 to 6 years, who visited the Guangdong Women and Children's Hospital for health examination between January 2016 and May 2017, were included in the present study. The serum 25(OH)D levels ranged from 10.5 to 307.4 nmol/L (mean ± standard deviation: 78.5 ± 26.3 nmol/L). The prevalence of vitamin D deficiency and insufficiency were 10.8% and 39.0%, respectively. The mean serum 25(OH)D level in spring (71.8 ± 24.9 nmol/L) was lower than that in other seasons. From January to April, we found a relatively high prevalence of vitamin D deficiency or insufficiency, both of which were also found to increase with age. Logistic regression analysis revealed that vitamin D deficiency and insufficiency were significantly associated with age and season. Deficiency and insufficiency of vitamin D are common among children in southern China, despite the area receiving sufficient sunlight.

Background: Cow's milk protein allergy (CMPA) is commonly seen in children. There have been no reports of the true prevalence of CMPA in Chinese infants. The aim of this population‐based study is to determine the prevalence, clinical characteristics, and outcome of CMPA in Chinese infants. Methods: We carried out a prospective survey in 7 participating hospitals throughout southern China. We included infants ≤12 months of age during the survey. For those suspected of CMPA, oral food challenge with cow's milk protein (CMP) was performed. A follow‐up telephone interview was conducted at 12 months after the diagnosis to assess the clinical outcome of CMPA. Results: A total of 9910 questionnaire surveys were distributed and 7364 (74.3%) were returned. The eligible survey number of surveys was 6768 (91.9%). A total of 182 infants was confirmed with CMPA, including 13 with anaphylactic reactions, 28 with clinical symptoms and serum immunoglobulin E (sIgE) >3.5 IU/mL, and 141 with positive CMP challenge test. The prevalence of CMPA was 2.69%. Infants with confirmed CMPA had significantly stronger family history of either 1 or both parents with food allergy, higher Cesarean section rate, and lower rate of breastfeeding, compared with those without CMPA. At 12‐month telephone follow‐up of 176 CMPA infants, 136 infants (77.3%) had become tolerant to CMP. Conclusions: The prevalence of CMPA was 2.69%. CMPA infants had a strong family history of food allergy and atopy. Both Cesarean delivery and formula feeding were risk factors for CMPA. At 12‐month follow‐up, the majority of CMPA infants had become tolerant to CMP.

Departmental sources Background: The influence of maternal vitamin D on pregnancy outcomes, including preterm birth (PTB), is unclear due to different experimental designs and study populations (patient race and sample size) of previous studies. We aimed to investigate the relationship between 25-hydroxyvitamin D (25[OH] D) levels and PTB among pregnant women in southern China. Material/Methods: A total of 11 641 pregnant women were retrospectively enrolled between January 2016 and April 2019. Vitamin D concentrations were evaluated by electrochemiluminescence immunoassay. Logistic regression analysis was used to analyze the association between vitamin D and PTB. Results: The average 25(OH) D concentration was 59.3±21.5 nmol/L; 34.8% of patients were vitamin D deficient, 43.0% were vitamin D insufficient (25[OH] D <50 nmol/L and 50-74.9 nmol/L, respectively). In total, 3.6% of newborns were born prematurely. Comparing the pre-term and full-term groups, 45.7% versus 42.9% and 29.8% versus 35% were vitamin D deficient and insufficient, respectively These differences were not significant (P>0.05). However, the mean vitamin D status was significantly different between the pre-term and full-term groups (61.3±21.3 and 59.1±21.5 nmol/L, respectively). No association was found between vitamin D deficiency/insufficiency and PTB in unadjusted or adjusted models, compared with vitamin D sufficiency (adjusted odds ratio, 1.016; 95% confidence interval, 0.794-1.301 and 0.842; 0.641-1.106, respectively). Conclusions: Low maternal 25(OH) D levels are common in southern China. However, low vitamin D status in pregnant women appears to be unrelated to PTB. Measuring vitamin D level alone is therefore not sufficient to predict PTB.

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Purpose: Evidence on the role of the gut microbiota in atopic dermatitis is inconsistent as human intestinal microbiota is influenced by geography. This cross-sectional study therefore aimed to compare differences in the gut microbiota of infants with atopic dermatitis and healthy infants in Guangzhou, China, by analyzing their stool. Patients and Methods: The composition of the intestinal microbiota was analyzed from the stool samples of 20 infants with atopic dermatitis (AD group) and 25 healthy infants (non-AD group) (1-6 months old), using full-length 16S rRNA gene sequencing. The Wilcoxon test was used to analyze the relative abundance of bacteria by phylum, family, genus, and species between groups; microbial community richness and diversity were compared between the two groups. Results: There were no significant differences in the microbial community richness and diversity between the two groups. At the phylum level, 11 bacterial phyla were found; most sequences belonged to one of the three dominant bacterial phyla -Firmicutes, Proteobacteria, and Bacteroidetes. The top 10 microbes at the phylum, family, and genus levels showed no significant changes in their composition within the gut microbiota between the AD and non-AD groups. A decrease in the ratio of the Streptococcus genus was found in atopic dermatitis group when compared with healthy controls (p=0.048). Conclusion:A decrease in the abundance of Streptococcus was found in children with AD. The role of Streptococcus in the development of AD needs to be confirmed in a large cohort study.

Background:The effect of maternal vitamin D status on the birth weight of offspring is controversial as the results are inconsistent between different populations. This large 2 retrospective cohort study aimed to assess the relationship between maternal vitamin D levels and birth weight of neonate. Methods: Serum samples were collected from 10,586 Chinese women in the 2 nd trimester of pregnancy, and the 25-hydroxyvitamin D [25(OH)D] level of the participants was assessed.Using the INTERGROWTH-21st standards, the offsprings were classified into three groups based on their gestational age and birth weight, which were as follows: small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA). Results:The average maternal vitamin D concentration was 61.1 nmol/L. The 25(OH)D concentrations were <75.0, <50.0, and <25.0 nmol/L in 76.6%, 31.1%, and 1.6% of the participants, respectively. Approximately 6.4%, 86.4%, and 7.2% of women delivered SGA, AGA, and LGA infants, respectively. No significant differences were observed in vitamin D levels between the three groups (P = 0.562). With the increase in 25(OH)D levels, the risk of SGA and LGA tended to increase and decrease, respectively. However, the results were not precise. AGA was not affected by 25(OH)D levels. The results of the curve fitting and threshold effect analyses did not support the correlation between vitamin D levels and SGA orLGA. Based on the univariate prediction model and the model that adjusted for the risk factors, the area under the curve was extremely small. Thus, 25(OH)D level is not an effective predictor of SGA and LGA.Conclusions: Low maternal vitamin D levels were not associated with SGA or LGA.

Objective Research is limited regarding biochemical markers of bone metabolism among children with cow’s milk protein allergy (CMPA). We aimed to determine differences in vitamin D and bone metabolism markers between infants with CMPA and healthy infants and explore relationships between these in a cross-sectional study. Methods In total, we included 41 children diagnosed with CMPA and under systematic medical and nutritional care at our center, and 50 healthy children as a control group. We reviewed demographic and clinical characteristics and measured serum biomarkers. Results We found that serum 25-hydroxyvitamin D (25(OH)D) levels among infants in the CMPA group were significantly lower than those in the control group, and levels of bone-specific alkaline phosphatase (BALP), serum phosphorus, and serum calcitonin were reduced. Pearson correlation analysis showed that serum 25(OH)D concentrations in the CMPA group were negatively correlated with parathyroid hormone but not significantly correlated with calcitonin and BALP. Logistic regression showed that CMPA was a risk factor for vitamin D deficiency. Conclusions Our study indicated that CMPA was associated with disturbances in bone metabolism. Levels of vitamin D in children with CMPA were lower than those in healthy children. CMPA was a risk factor for vitamin D deficiency.

Abstract Background: The effect of maternal vitamin D status on the birth weight of offspring is controversial as the results are inconsistent between different populations. This large retrospective cohort study aimed to assess the relationship between maternal vitamin D levels and birth weight of neonate. Methods: Serum samples were collected from 10,586 Chinese women in the 2 nd trimester of pregnancy, and the 25-hydroxyvitamin D [25(OH)D] level of the participants was assessed. Using the INTERGROWTH-21st standards, the offsprings were classified into three groups based on their gestational age and birth weight, which were as follows: small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA). Results: The average maternal vitamin D concentration was 61.1 nmol/L. The 25(OH)D concentrations were <75.0, <50.0, and <25.0 nmol/L in 76.6%, 31.1%, and 1.6% of the participants, respectively. Approximately 6.4%, 86.4%, and 7.2% of women delivered SGA, AGA, and LGA infants, respectively. No significant differences were observed in vitamin D levels between the three groups (P = 0.562). With the increase in 25(OH)D levels, the risk of SGA and LGA tended to increase and decrease, respectively. However, the results were not precise. AGA was not affected by 25(OH)D levels. The results of the curve fitting and threshold effect analyses did not support the correlation between vitamin D levels and SGA or LGA. Based on the univariate prediction model and the model that adjusted for the risk factors, the area under the curve was extremely small. Thus, 25(OH)D level is not an effective predictor of SGA and LGA. Conclusions: Low maternal vitamin D levels were not associated with SGA or LGA.