Question: Should vitamin D supplementation be recommended as part of preconception care?
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Answer: The Cochrane systematic review on preconception lifestyle advice for women with subfertility(1) cites 3 guidelines that recommend “that women with dark skin or who get little sun exposure are screened in the perinatal period for vitamin D deficiency and given vitamin D supplements, if necessary” (2-4)
(Evidence level IV)
Most other evidence relates to supplementation during pregnancy, and the RCOG Scientific Opinion Paper on vitamin supplementation(5) says:
“The NICE guidelines for antenatal care [...] incorporate an additional recommendation on informing women of the importance of maintaining adequate vitamin D stores in pregnancy, particularly for those at greatest risk of vitamin D deficiency (women of South Asian, African, Caribbean or Middle Eastern family origin, women who have limited exposure to sunlight, women who eat a diet particularly low in vitamin D and women with a prepregnancy body mass index above 30 kg/m²) who may choose to take vitamin D at a rate of 10 micrograms/day. This stance was endorsed by the Scientific Advisory Committee on Nutrition. The current lack of evidence of benefit for women at lower risk of vitamin D deficiency points to the need for further research into vitamin D supplementation in pregnant women with clinical neonatal and infant end-points under scrutiny. There is a similar gap in the knowledge base for optimal dosing, as there is little empirical robust evidence to support 10 micrograms/day. Further research is required, particularly to establish the dose needed to supplement pregnant women with pre-existing deficiency and the optimal gestation at which vitamin D supplementation should be started.”
(Evidence level IV)
A systematic review of health-related outcomes related to vitamin D (6) found only one B-rated nested case-cohort study reporting an association between low 25(OH)D concentration (<37.5 nmol/L) early in pregnancy and preeclampsia. [The report] did not identify any eligible studies on the relationship of vitamin D and maternal hypertension, preterm birth, or small infant for gestational age.
(Evidence level III)
References:
- Anderson K, Norman RJ, Middleton P. Preconception lifestyle advice for people with subfertility. Cochrane Database of Systematic Reviews 2010, Issue 4. Art. No.: CD008189. DOI: 10.1002/14651858.CD008189.pub2 Abstract and free full text in some locations. Full text is also available here for Fellows, Members and Trainees.
- Government of South Australia Department of Health. South Australian Perinatal Practice Guidelines - Chapter 1 Preconception Advice.
- Preconception care: a good beginning. The Hague: Health Council of the Netherlands, 2007; publication no. 2007/19E.
- Harris M, Bennett J, Del Mar C, Fasher M, Foreman L, Furler J, et al. Guidelines for preventive activities in general practice. 7th Edition. South Melbourne, Australia: The Royal Australian College of General Practitioners, 2009.
- Vitamin supplementation in pregnancy (SAC Opinion Paper 16). RCOG, 2009
- Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J, Lichtenstein A, Patel K, Raman G, Tatsioni A, Terasawa T, Trikalinos TA. The Relationships of Vitamin D and Calcium Intakes to Nutrient Status Indicators and Health Outcomes. Evidence Report No. 183 (Prepared by the Tufts Evidence-based Practice Center under Contract No. HHSA 290-2007-10055-I.) AHRQ Publication No. 09-E015. Rockville, MD: Agency for Healthcare Research and Quality. June, 2009.
Search date: June 2010
Classification of evidence levels
Ia Evidence obtained from meta-analysis of randomised controlled trials.
Ib Evidence obtained from at least one randomised controlled trial.
IIa Evidence obtained from at least one well-designed controlled study without randomisation.
IIb Evidence obtained from at least one other type of well-designed quasi-experimental study.
III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.
IV Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities.
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