British Journal of Nutrition

Full Papers

Human and Clinical Nutrition

Vitamin D deficiency and insufficiency in pregnant women: a longitudinal study

Valerie A. Holmesa1, Maria S. Barnesa2 c1, H. Denis Alexandera3, Peter McFaula4 and Julie M. W. Wallacea2

a1 Nursing and Midwifery Research Unit, School of Nursing and Midwifery, Queen's University, Belfast BT9 5BN, UK

a2 Northern Ireland Centre for Food and Health (NICHE), University of Ulster, Coleraine BT52 1SA, UK

a3 Department of Haematology, Belfast City Hospital, Belfast BT9 7AB, UK

a4 Department of Obstetrics and Gynaecology, Belfast City Hospital, Belfast BT9 7AB, UK


Maternal vitamin D insufficiency is associated with childhood rickets and longer-term problems including schizophrenia and type 1 diabetes. Whilst maternal vitamin D insufficiency is common in mothers with highly pigmented skin, little is known about vitamin D status of Caucasian pregnant women. The aim was to investigate vitamin D status in healthy Caucasian pregnant women and a group of age-matched non-pregnant controls living at 54–55°N. In a longitudinal study, plasma 25-hydroxyvitamin D (25(OH)D) was assessed in ninety-nine pregnant women at 12, 20 and 35 weeks of gestation, and in thirty-eight non-pregnant women sampled concurrently. Plasma 25(OH)D concentrations were lower in pregnant women compared to non-pregnant women (P < 0·0001). Of the pregnant women, 35, 44 and 16 % were classified as vitamin D deficient (25(OH)D < 25 nmol/l), and 96, 96 and 75 % were classified as vitamin D insufficient (25(OH)D < 50 nmol/l) at 12, 20 and 35 weeks gestation, respectively. Vitamin D status was higher in pregnant women who reported taking multivitamin supplements at 12 (P < 0·0001), 20 (P = 0·001) and 35 (P = 0·001) weeks gestation than in non-supplement users. Vitamin D insufficiency is evident in pregnant women living at 54–55°N. Women reporting use of vitamin D-containing supplements had higher vitamin D status, however, vitamin D insufficiency was still evident even in the face of supplement use. Given the potential consequences of hypovitaminosis D on health outcomes, vitamin D supplementation, perhaps at higher doses than currently available, is needed to improve maternal vitamin D nutriture.

(Received November 05 2008)

(Revised January 26 2009)

(Accepted February 09 2009)

(Online publication March 31 2009)


c1 Corresponding author: Dr Maria S. Barnes, fax +44 28 7032 3023, email


Abbreviations: 25(OH)D, 25-hydroxyvitamin D