Study on Vitamin D Deficiency in Pregnant Women in Switzerland

Importance of Vitamin D

Vitamin D plays a crucial role in human growth and development, yet its deficiency is a significant global health concern. Recent studies have highlighted the implications of vitamin D deficiency in pregnant women, linking it to conditions such as preeclampsia, gestational diabetes, and preterm delivery. Notably, vitamin D levels in pregnant women are closely associated with those in umbilical cord blood, indicating that maternal deficiency may adversely impact fetal development.

Research Goals and Methodology

In response to these concerns, researchers in Switzerland aimed to investigate the vitamin D status of women in their third trimester of pregnancy, along with the levels present in the umbilical cord blood of their newborns. Their findings were published in the British Journal of Nutrition. The study was conducted from August 2014 to June 2016 across hospitals in Zurich, Bellinzona, and Samedan, involving 305 pregnant women and their 278 newborns.

The selection of these cities allowed for the examination of varying cultural, socio-demographic, and meteorological influences. Zurich, a populous city, has a mild climate; Bellinzona, situated in the Italian-speaking region, enjoys abundant sunshine; while Samedan is a rural area characterized by high altitudes and cooler temperatures.

Blood samples were collected from the pregnant participants during their final routine examination and from the umbilical cord post-delivery. Researchers measured serum 25-hydroxyvitamin D (25(OH)D) levels, defining deficiency as less than 50 nmol/L and sufficiency as greater than 50 nmol/L. Questionnaires were utilized to identify potential determinants of vitamin D deficiency.

Findings on Vitamin D Deficiency

The study’s results indicated that 53.4% of the women in their third trimester were vitamin D deficient, with a median serum 25(OH)D concentration of 46.0 nmol/L. Analysis of umbilical cord blood revealed that 49.8% of newborns also exhibited vitamin D deficiency, with a median serum 25(OH)D concentration of 50 nmol/L. A strong correlation was found between the vitamin D levels of mothers and their infants.

Four primary determinants of vitamin D deficiency were identified: the study center, the mother’s country of origin, the season during the pregnancy, and the use of vitamin D supplements. Additionally, four secondary determinants emerged, including body mass index (BMI) near term, skin color, maternal education, and sunscreen usage.

Implications of the Findings

The overall prevalence of vitamin D deficiency was 53% among pregnant women and 49.8% in their newborns’ cord blood. These findings underscore the widespread occurrence of vitamin D deficiency within this demographic, highlighting the associated health risks. Despite 71% of the women reporting the use of vitamin D or multivitamin supplements, a significant proportion still exhibited deficiency, suggesting inadequate intake levels.

The authors of the study emphasize the need for enhanced focus on sufficient vitamin D supplementation during pregnancy, as it represents the most modifiable determinant of deficiency.

Conclusion

This research contributes to the understanding of vitamin D deficiency in pregnant women and its potential impact on fetal health. Future studies and clinical practices should prioritize effective strategies for ensuring adequate vitamin D levels during pregnancy.

Written by Caitlin M. Byrne, BSc

Reference: Krieger, J., Cabaset, S., Canonica, C., Christoffel, L., Richard, A., Schröder, T.,… Lötscher, K.Q. (2018). Prevalence and determinants of vitamin D deficiency in the third trimester of pregnancy: a multicentre study in Switzerland. British Journal of Nutrition, 2018 Jan 10. https://doi.org/10.1017/S0007114517003634