Mothers, babies and vitamin D: old disease, new problem

Birth season and vitamin D concentration in adulthood

BACKGROUND

Recent evidences suggest that the season of birth may influence human development and vulnerability to develop certain diseases.

METHODS

A retrospective analysis was hence carried out in the laboratory information system of the University Hospital of Parma (North-West Italy), to retrieve values of total serum vitamin D (25-hydroxyvitamin D) measured in a the whole cohort of unselected outpatients age 18 years and older referred for routine health check-up during January to December 2014. Vitamin D was then stratified according to birth season.

RESULTS

The study population consisted in 11,150 unselected Italian residents (median age 62 years; 8,592 women and 2,558 men). Serum vitamin D values were found to be significantly lower in subjects born in winter than in those born in spring and summer. More specifically, winter season birth was associated with 11% increased risk of developing vitamin D deficiency later in life compared to spring birth. Daily sunlight hours at birth independently predicted vitamin D concentration in adulthood.

CONCLUSIONS

The results of this large, cross-sectional retrospective investigation attest that subjects born in winter have a total vitamin D concentration in adulthood that is significantly lower than those born in seasons with longer daylight periods.

Determinants of hypovitaminosis d in pregnant women and their newborns in a sunny region

Introduction. This study aims to assess the factors associated with 25-hydroxy vitamin D (25(OH)D) levels in pregnant women and their newborns in a sunny region. Materials and Methods. This cross-sectional study was conducted in 2012 in Isfahan, Iran. It comprised 100 nulliparous singleton pregnant women, selected by random cluster sampling. Laboratory tests were assessed before delivery in mothers and after delivery in their infants' umbilical cord blood. The P for trend of variables was assessed across the air quality index (AQI) quartiles. The associations of AQI and 25(OH)D were assessed by multiple linear regression after adjustment for age, body mass index, and dietary intake. Results. Sera of 98 mothers and an equal number of newborns were analyzed. The median (interquartile range, IQR) of serum 25(OH)D of mothers and neonates was 15.1(12.6, 18.2) ng/mL in mothers and 15.7(12.0, 18.1) ng/mL in neonates, respectively. AQI had an inverse association with serum 25(OH)D (Beta = -0.58, P = 0.04). The corresponding figure was also inverse and significant for newborns (Beta (SE)= -0.51(0.04), P = 0.01). Conclusion. The independent inverse association of 25(OH)D with air quality can explain the high prevalence of hypovitaminosis D in pregnant women living in this sunny region.