Why you might see this term
UK advice includes seasonal supplementation, with some people advised to take it throughout the year. Check guidance for your personal circumstances.
What to keep in mind
A low vitamin D result is not, by itself, an explanation for infertility. More is not always better; avoid high doses without appropriate advice.
Sources & further reading
Prepared by ProFertility · Updated 23 October 2026.
Educational information based on the linked sources. This explanation is not an individual diagnosis or a treatment recommendation. A term appearing here does not mean the test is necessary or included in a particular kit.
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