Vitamin D supplementation for women before and during pregnancy: an update of the guidelines, evidence, and role of GPs and practice nurses

UK National Institute for Health and Care Excellence (NICE) guidance (2014) advises that 10 µg vitamin D should be taken by all women throughout pregnancy, ideally starting prior to conception.1,2 However, the terminology used and practicalities of implementing this advice can be confusing, as can the role of the GP and practice nurse regarding the provision of supplementation; — particularly as their involvement in routine antenatal care is tending to diminish. This article summarises the evidence and related guidance on managing vitamin D status in pregnant women, and provides an update on the ways in which women can obtain the necessary supplements. Vitamin D is not only integral to calcium homeostasis and bone health, but it also has multiple other sites of action throughout the body, including the pancreas, skin, intestine, and immune system. In the UK, dietary sources of vitamin D are limited and account for only 10–20% of the total body store; natural sources include oily fish, egg yolk, and red meat, while fortified foods include infant and toddler formula milks, some breakfast cereals, and margarines. The majority of vitamin D is from skin synthesis following exposure to sunlight, although in the UK the necessary wavelength of ultraviolet radiation is only available between April and mid-October.1,3 Most laboratories measure serum 25-hydroxyvitamin D (25[OH]D) as a reflection of current vitamin D stores, which equates to the levels produced cutaneously and through …