Sociodemographic factors related to plasma concentrations of 25-OH vitamin D and PTH in cord blood

Background. Plasma 25(OH)D levels in the newborn are dependent on maternal stores, thus, neonates of vitamin D-deficient mothers present a greater risk of hypocalcaemia, rickets and infections the first year of life. Several studies showing a high prevalence of vitamin D deficiency in pregnant women have been published recently. The aim of the study is to analyze the levels of 25(OH)D in cord blood and determine whether there is a relation with nutritional, socioeconomic and clinical factors of pregnant women and their newborns. Metthods. Between March and May 2013, 99 pregnant women were recruited in Hospital del Mar (Barcelona), in whom plasma 25(OH)D and PTH levels were measured in cord blood at birth. Clinical history data were collected and a nutritional survey was made on maternal vitamin D and calcium intake and sun exposure. Statistical analysis was performed using SPSS. Comparisons were performed using Kruskal-Wallis and Mann-Whitney U tests, and correction for multiple comparisons using Bonferroni. P value <0.05 and <0.0083 for multiple comparisons were considered statistically significant. Results. Mean 25(OH)D value in cord blood was 10.4±6.1 ng/ml. 94% of pregnant women had 25(OH)D levels in cord blood <20 ng/ml. Vitamin D and calcium intake was considered adequate in 92% although sun exposure was deficient in 47%. A correlation between serum 25(OH)D and vitamin D (p 0.033) and calcium intake (p 0.005), sun exposure (p<0.001), ethnicity (p<0.001), skin phototype (p<0.001) and use of traditional clothing (p<0.001) was found. Conclusions. There is a high prevalence of low levels of vitamin D after winter months in cord blood. The lowest 25(OH D levels were observed in Indo-Pakistani ethnicity, dark phototype and deficient sun exposure.