Lag associations of gestational phthalate exposure with maternal serum vitamin D levels: Repeated measure analysis.

Few studies have investigated the relationships between gestational phthalate exposure and maternal circulating vitamin D. In the Ma'anshan birth cohort, 3265 pregnant women were included. Each woman provided up to three urine and serum samples for measurement of phthalates and 25(OH)D and calcium, respectively. Linear mixed models were performed to analyse the association between phthalate metabolites and 25(OH)D and calcium. Stratified analyses of the relationship between phthalates and 25(OH)D by urine collection season were conducted. Finally, the post hoc lag effect of phthalate exposure on 25(OH)D was determined if longitudinal associations were significant. Some phthalate metabolites were associated with increased 25(OH)D but with decreased calcium. Furthermore, the relationship of phthalate exposure with 25(OH)D varied with urine collection season. Phthalate metabolites collected in summer and autumn were associated with an increase in 25(OH)D, while monobenzyl phthalate collected in winter and spring was inversely associated with 25(OH)D. Finally, high-molecular-weight phthalates had lag associations with 25(OH)D with a 1-trimester lag period. Low-molecular-weight phthalates exhibited lag associations with 25(OH)D with a 2-trimester lag period. In conclusion, the positive cross-sectional correlation between phthalate metabolites and 25(OH)D was partly affected by urine collection season. This study suggested that gestational phthalate exposure would have a lag association with maternal 25(OH)D levels.

VDR Variants rather than Early Pregnancy Vitamin D Concentrations Are Associated with the Risk of Gestational Diabetes: The Ma'anshan Birth Cohort (MABC) Study.

AIM: This study investigated the associations among early pregnancy vitamin D concentrations, seasonality, and vitamin D metabolic gene variants and how these variables related alone and in interaction with the risk of gestational diabetes mellitus (GDM). METHODS: Research participants were women from the Ma'anshan birth cohort study in China. The overall study included 3110 women to explore the association between early pregnancy vitamin D concentrations and the risk of GDM. In the current analysis, a nested case-control study of 274 GDM cases and 380 controls was conducted to investigate seven vitamin D metabolic gene variants and the risk of GDM. Vitamin D concentrations were measured by radioimmunoassay. Genotypes were determined by improved multiple ligase detection reaction. Interactions between genetic variants and vitamin D as predictors of the risk of GDM were evaluated by a pair-wise analysis under a multiplicative interaction model. RESULTS: Vitamin D concentrations were not significantly associated with the risk of GDM (OR = 0.79, 95% CI = 0.55-1.13) after adjusting for seasonality. Fall-winter conceptions had a 37% decreased risk of GDM compared with spring-summer conceptions (OR = 0.63, 95% CI = 0.49-0.81), independent of vitamin D concentrations. Two VDR gene variants rs1544410 (OR = 2.03, 95% CI = 1.17-3.51 for CT versus CC) and rs731236 (OR = 2.42, 95% CI = 1.29-4.55 for GA versus AA) were significantly associated with the risk of GDM. No interactions among genetic variants and vitamin D concentrations were detected. CONCLUSION: Early pregnancy vitamin D insufficiency or deficiency was not significantly associated with the risk of GDM. The results of this study emphasize the importance of genetic variants in VDR and conception season as factors that affect the risk of GDM.

Maternal intelligence quotient and motor development in early childhood: The mediating role of mother's education.

AIM: To examine the association between maternal intelligence quotient (IQ) and early childhood motor development and whether maternal education mediates this relationship. METHODS: Data were collected prospectively in the Ma'anshan Birth Cohort study. Maternal IQ was assessed using the Wechsler Adult Intelligence Scale-Revised by China (WAIS-RC). Information on baseline characteristics and maternal education was obtained from questionnaires and medical records. The study outcome was motor development evaluated at 18 months by the Third Edition of Ages and Stages Questionnaire. Logistic regression analyses and mediation analyses were used. RESULTS: Of 2739 valid subjects (84% follow-up), the rate of developmental delay was 3.1% in the gross motor domain and 6.2% in the fine motor domain. The mean value for maternal IQ was 96.2 (standard deviation 10.6). About 40.3% of the mothers had secondary education or less, while 59.7% had a college education. Mothers with higher IQ had a significantly higher educational level and had children with better motor development. Maternal education significantly mediated the association between maternal IQ and fine motor development. There was a direct effect of maternal IQ on gross motor development, but the mediation effect of maternal education was not found. CONCLUSIONS: Maternal IQ was associated with motor development. Maternal education played an important role in reducing the disparities in fine motor development among children of different maternal IQs.