The Importance of Vitamin D Testing when Trying to Conceive
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The Importance of Vitamin D Testing when Trying to Conceive

The Importance of Vitamin D Testing when Trying to Conceive

September 2, 2021

Sarah Trimble, Nutritional Therapist, explains how one of the most common nutrient deficiencies can negatively impact fertility in both men and women.

Trying to conceive can be a stressful and emotional time for some couples, especially as around 1 in 7 couples struggle to get pregnant. A fertility health check can be a key way to take control of your conceptual health by providing you with key information about your hormonal and nutritional health, specifically those nutrients that we know can directly impact fertility. Testing for and then treating vitamin D deficiency is a relatively easy and straightforward way to improve both male and female fertility and improve chances of conceiving.

Vitamin D: why it’s difficult to get enough

Vitamin D is an essential nutrient to test when trying to conceive, in fact vitamin D acts more like a hormone in our bodies because it controls a number of important bodily functions – some of which are key reproductive functions. It is almost impossible to know if you are getting enough vitamin D because our main source is sunlight. When UVB rays hit our skin they stimulate a chemical reaction in the body that results in vitamin D production and we rely on the action of sunlight for around 80-90% of our vitamin D stores. You can find small amounts of vitamin D in foods such as eggs, liver, oily fish and mushrooms, however, we can’t get adequate vitamin D levels from diet alone.

Our reliance on sunlight to produce vitamin D is one reason why it is estimated that around 50% of the UK population are vitamin D deficient. In the UK we don’t get enough strong sunshine throughout the year, in fact from October to March the sun’s rays are not strong enough to stimulate vitamin D production. Spending time in the sun during the spring and summer months can build vitamin D stores, however, the body can quickly use up these stores over the autumn and winter months.

It can be difficult to predict vitamin D levels and there are a number of risk factors for developing a vitamin D deficiency.

Risk factors for vitamin D deficiency

Inadequate sunlight exposure: we should be exposing our skin to sunlight between 12-3pm, when most of us are at work.

Dark skin colour: individuals with darker skin need more sunlight to stimulate vitamin D production and can find it difficult to get enough in the UK climate.

Obesity: fat tissue absorbs and retains vitamin D, making it inactive

Poor absorption: digestive issues that affect absorption of dietary vitamin D include gallbladder removal and coeliac disease

Vitamin D and Female Fertility

Having a good level of vitamin D stored in the body can have a strong positive impact on female fertility. Better vitamin D levels increase chances of both conceiving and staying pregnant (in some research women with better vitamin D levels were 3 times more likely to get pregnant). In fact vitamin D deficiency is considered a risk factor for miscarriage. Having higher blood levels of vitamin D can also improve symptoms of both PCOS and endometriosis – the two most common conditions that reduce female fertility.

Immune system imbalances can negatively impact a woman’s chances of conceiving and increase risk of miscarriage. Improving vitamin D stores is an important and straightforward way to rebalance the immune system. Vitamin D acts as an immune system modulator, balancing an immune system that might be underactive or overactive. The research shows that women with better vitamin D levels in the pre-conceptual period have reduced risk of miscarriage and better rates of conception during IVF. It is recommended that all women who are trying to conceive, either naturally or through IVF should test their vitamin D status so that appropriate steps can be taken to achieve and maintain healthy vitamin D stores.

Vitamin D and Male Fertility

In male fertility vitamin D has been shown to have a positive impact on sperm health and there is a clear relationship between better blood levels of vitamin D and better semen quality. When compared to men who were deficient in vitamin D, men who had sufficient vitamin D levels had better sperm quality, specifically sperm concentration and motility. Vitamin D is linked to testosterone production and men with low testosterone levels saw an improvement after spending more time in the summer sun and naturally increasing their vitamin D. In one study infertile men who were treated for vitamin D deficiency saw their testosterone levels and sperm quality improve in line with improved vitamin D levels.

Optimising vitamin D levels to promote conception

Dietary intake of vitamin D can only have a moderate impact on vitamin D levels and, outside of the summer months, supplementation of vitamin D is essential to achieve a good vitamin D status. Prenatal multivitamins generally provide vitamin D at levels of around 400-600i.u., which will only maintain blood vitamin D levels and not treat deficiency. Testing vitamin D levels is a key first step to determine if deficiency is present. With an understanding of your personal vitamin D levels a qualified medical professional, such as a registered Nutritional Therapist, can help you develop an appropriate and safe supplementation protocol.

Learn more about your fertility and nutrient status

Whether you’re just curious for the future, or actively trying to conceive, you can book a blood test directly via Melio, at a time that suits you.

A trained health professional at one of our partner clinics will perform the blood draw, and send the sample to one of our UKAS accredited labs. All test results are individually checked by one of our in-house doctors, who will also write you a personal medical report with any further advice and guidance you may need.

Learn more and order your Melio blood test by clicking on a product below, or use the chat button if you’d like talk to one of our specially trained advisors for more information.


Parva NR, Tadepalli S, Singh P, et al. Prevalence of Vitamin D Deficiency and Associated Risk Factors in the US Population (2011-2012). Cureus. 2018;10(6):e2741.

Spiro A, Buttriss JL. Vitamin D: An overview of vitamin D status and intake in Europe. Nutr Bull. 2014;39(4):322‐350.

Calvo MS, Calvo MS, Whiting SJ, et al. Vitamin D intake: a global perspective of current status. The Journal of Nutrition. 2005;135:310–316

Lerchbaum E, Rabe T. Vitamin D and female fertility. Curr Opin Obstet Gynecol. 2014 Jun;26(3):145-50.

Lin MW, Wu MH. The role of vitamin D in polycystic ovary syndrome. Indian J Med Res. 2015;142(3):238-240.

Andersen LB, Jørgensen JS, Jensen TK, Dalgård C, Barington T, Nielsen J, Beck-Nielsen SS, Husby S, Abrahamsen B, Lamont RF, Christesen HT. Vitamin D insufficiency is associated with increased risk of first-trimester miscarriage in the Odense Child Cohort. Am J Clin Nutr. 2015 Sep;102(3):633-8.

Mumford SL, Garbose RA, Kim K, Kissell K, Kuhr DL, Omosigho UR, Perkins NJ, Galai N, Silver RM, Sjaarda LA, Plowden TC, Schisterman EF. Association of preconception serum 25-hydroxyvitamin D concentrations with livebirth and pregnancy loss: a prospective cohort study. Lancet Diabetes Endocrinol. 2018 Sep;6(9):725-732.

Gonçalves DR, Braga A, Braga J, Marinho A. Recurrent pregnancy loss and vitamin D: A review of the literature. Am J Reprod Immunol. 2018 Nov;80(5)

Alzoubi A, Mahdi H, Al Bashir S, et al. Normalization of serum vitamin D improves semen motility parameters in patients with idiopathic male infertility. Acta Endocrinol (Buchar). 2017;13(2):180-187.

Cito G, Cocci A, Micelli E, Gabutti A, Russo GI, Coccia ME, Franco G, Serni S, Carini M, Natali A. Vitamin D and Male Fertility: An Updated Review. World J Mens Health. 2020 Apr;38(2):164-177.

Kumari S, Singh K, Kumari S, Nishat H, Tiwary B. Association of Vitamin D and Reproductive Hormones With Semen Parameters in Infertile Men. Cureus. 2021 Apr 15;13(4):e14511.

Wehr E, Pilz S, Boehm BO, März W, Obermayer-Pietsch B. Association of vitamin D status with serum androgen levels in men. Clin Endocrinol (Oxf). 2010 Aug;73(2):243-8.

Pilz S, Frisch S, Koertke H, Kuhn J, Dreier J, Obermayer-Pietsch B, Wehr E, Zittermann A. Effect of vitamin D supplementation on testosterone levels in men. Horm Metab Res. 2011 Mar;43(3):223-5.

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