Abstract.Few studies have examined how vitamin C status is affected in diabetic pregnancy and no comparison between normal and diabetic pregnancies has been found. This study evaluated vitamin C status prospectively during pregnancy in women with type 1 diabetes mellitus (n=76), in non-diabetic women (n=60), and in their respective neonates. Vitamin C was lower in diabetic women throughout all trimesters compared to controls (p<0.01). Repeated measurements analysis showed significant differences between diabetic and non-diabetic women; also when adjusted for birth weight ratio and age. In non-diabetic women, vitamin C levels were lower in 3rd trimester compared to 1st and 2nd trimester (both p<0.05). Poor vitamin C status - defined as a plasma concentration <23µM - was found in 51% and 12% of the diabetic and nondiabetic women, respectively, at some stage during pregnancy. Umbilical cord vitamin C levels were higher than in the diabetic as well as in the non-diabetic mothers (p<0.01). The umbilical vitamin C was two to three times higher than maternal vitamin C. In conclusion, our results suggests that vitamin C status is lower in pregnant women with type 1 diabetes, while no effect on vitamin C status was observed in the neonates of diabetic women based on umbilical measurements.