[Vitamin D levels in maternal--VLBW infants pairs]

Normal foetal growth depends on sufficient mother's vit D intake. Premature birth interrupts vit D and mineral mother-to-foetus transfer and leads to vit D deficiency and disturbs newborn mineral bone metabolism.

To determine vit. D plasma levels in mothers and their very low birth weight- (VLBW) newborns and the prevalence of vit D deficiency in this population, to investigate seasonal variation and analyse babies' vit D levels from birth to the 8 postnatal week.

The study has been carried out in the University hospital "Maichin dom" Sofia for the period 09.2011-01.2012 and there have been investigated 32 women and their 39 VLBW infants as a target group. 25-OHD level has been measured in maternal and newborn cord blood samples. The ECLIA method has been used. 25-OHD level has been tested second time at eight weeks of age in 34 infants. According to the maternal vit D levels the patients have been divided into 3 groups: Group. 1--vit D reference range level (> 30 ng/ml); Group. 2--vit D insufficiency (21-29 ng/ml), Group. 3--vit D deficiency (< 20 ng/ml).

Low Vit. D levels have been estimated in 62.5% of mothers' group. Nevertheless, only 38.6% of all babies have been Vit. D deficient. In 61.4% of them vit D has been in normal range (32.4-35.7 ng/ml). A significant positive correlation between maternal and infants' vit D level at birth has been established (r = 0.516; p = 0.002). There have been found a significant seasonal dependence of vit D level at birth in the group too: vit D plasma levels have been estimated higher in September-October group compared to those in November-January group. Most of the blood samples in winter months showed lower vit. D levels than the autumn group. At 8 weeks of age 67.6% of the babies have been with vit D insufficiency. There has been a significant positive correlation between 25-OHD levels at birth and at weeks (r = 0.425; p = 0.012).

Vit. D insufficiency has been found in 62.5% of the mothers at birth. Maternal vit. D deficiency is a significant risk factor for neonatal vit D deficiency. There is a clear seasonal dependency with a significantly lower 25-OHD level in the mothers and their VLBW babies in winter months.