BACKGROUND/OBJECTIVES: Vitamin D is required for bone growth and normal insulin 
secretion. Maternal hypovitaminosis D may impair fetal growth and increase the 
risk of gestational diabetes. We have related maternal vitamin D status in 
pregnancy to maternal and newborn glucose and insulin concentrations, and 
newborn size, in a South Indian population.
SUBJECTS/METHODS: Serum 25 hydroxy vitamin D (25(OH)D) concentrations, glucose 
tolerance, and plasma insulin, proinsulin and 32-33 split proinsulin 
concentrations were measured at 30 weeks gestation in 559 women who delivered at 
the Holdsworth Memorial Hospital, Mysore. The babies' anthropometry and cord 
plasma glucose, insulin and insulin precursor concentrations were measured.
RESULTS: In total 66% of women had hypovitaminosis D (25(OH)D concentrations <50 
nmol l(-1)) and 31% were below 28 nmol l(-1). There was seasonal variation in 
25(OH)D concentrations (P<0.0001). There was no association between maternal 
25(OH)D and gestational diabetes (incidence 7% in women with and without 
hypovitaminosis D). Maternal 25(OH)D concentrations were unrelated to newborn 
anthropometry or cord plasma variables. In mothers with hypovitaminosis D, 
higher 25(OH)D concentrations were associated with lower 30-min glucose 
concentrations (P=0.03) and higher fasting proinsulin concentrations (P=0.04).
CONCLUSIONS: Hypovitaminosis D at 30 weeks gestation is common in Mysore 
mothers. It is not associated with an increased risk of gestational diabetes, 
impaired fetal growth or altered neonatal cord plasma insulin secretory profile.