Aim: To study the relationship of maternal vitamin D level at the moment of delivery with gestational and infant outcomes. Materials and Methods: A single centre prospective cohort study. Main outcomes were birth weight percentile and respiratory tract infections in the first year, secondary outcomes gestational diabetes, preterm birth, pre-eclampsia, caesarean birth, and atopic dermatitis and gastroenteritis in the first year of life. Maternal vitamin D was determined in venous plasma after delivery, infant data were prospectively gathered through a diary kept by the parents. Results: A total of 240 deliveries was included. Vitamin D insufficiency was present in the large majority (n=205, 95.5%) In univariate analysis a significant association was found between vitamin D level < 10 ng/ml and birthweight < P10, but in multivariate analysis including parity, maternal age, fetal sex, gestational diabetes, maternal glucose level, and preeclampsia there was no significant contribution from low vitamin D. For only 37 (15%) infants complete follow up data for one year were available. An association was found between lower vitamin D and more than two respiratory tract infections; this relations disappeared when taking into account birthweight, breastfeeding, and having a sibling going to daycare. No relation was present between vitamin D and pre-eclampsia, caesarean birth, atopic dermatitis, and gastroenteritis. Conclusions: The actual cut off values for vitamin D should be questioned as over 90% of the population would be deficient. When considering other factors, maternal vitamin D at the moment of delivery does not correlate with birthweight percentile, respiratory tract infections in the first year of life, nor other frequent obstetric and infant problems.