AimThere is limited and conflicting evidence available regarding the correlation between maternal vitamin D status and childhood overweight and body mass index (BMI). The aim of this study was to investigate the following: (1) potential association between maternal 25‐hydroxyvitamin D (25(OH)D) levels and newborn growth status; (2) relationship between maternal 25OHD levels and BMI and the risk of overweight with preschoolers being overweight.MethodsA cohort of 3213 eligible singleton mother–infant pairs were used to investigate the possible associations between maternal 25(OH)D levels and fetal growth status. Data of 1767 available singleton mother–infant pairs and 6‐year‐old preschoolers was applied to analyze the potential correlations between maternal 25(OH)D status and risk of childhood overweight.ResultsCompared with sufficient 25(OH)D in pregnancy group (≥75 nmol/L), there were no correlations between the maternal 25(OH)D deficiency (<50 nmol/L) and large gestational age (LGA) (p = 0.465), small gestational age (SGA) (p = 0.607), lower birth weight (LBW) (p = 0.725) or fetal macrosomia (p = 0.535). Moreover, no significant associations between insufficient maternal 25(OH)D (50–75 nmol/L) and LGA (p = 0.505), SGA (p = 0.816), LBW (p = 0.816), or fetal macrosomia (p = 0.413) were observed. We found statistically significant disparities between the fetal birth weight and height (p < 0.001), weight (p < 0.001), head circumference (p = 0.001) of 6‐years preschooler. No significant associations were found between the maternal 25(OH)D levels and BMI and risk of overweight at 6‐year‐old preschoolers.ConclusionThere were no apparent correlation found between maternal 25(OH)D concentrations and fetal birth status. There was no evidence found to suggest the effect of maternal 25(OH)D level on overweight at 6‐year‐old preschoolers.