Various studies have shown that vitamin D sufficiency is associated with an increase in pregnancy rates and live births. In this article, we dive into the impact of vitamin D on female and male infertility, egg quality, IVF, fibroids, and miscarriage. 

By women’s health expert Halle Tecco, MPH, MBA

In addition to being important for bone health and immune function, emerging research shows that low vitamin D levels are associated with fertility problems, including PCOS, endometriosis, uterine fibroids, sperm health, and miscarriage. In fact, researchers have found that women with typical levels of vitamin D were 46 percent more likely to get pregnant and a third more likely to have a live birth than women with low levels of vitamin D.

Women with typical levels of vitamin D were 46 percent more likely to get pregnant and a third more likely to have a live birth than women with low levels of vitamin D.

Vitamin D and infertility

Vitamin D deficiency is associated with infertility. In fact, one study found that most infertile women (87.3%) have low levels of vitamin D. 

Can vitamin D help with ovulation? Research suggests that low levels of vitamin D are associated with a longer follicular phase (the time between the first day of the period and ovulation) and an overall longer menstrual cycle. However, there is not enough research to make conclusions about vitamin D supplements helping with ovulation. That being said, higher vitamin D levels may improve fertility and shorten the time it takes to get pregnant.

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Vitamin D deficiency and miscarriage

Repeat miscarriage (aka recurrent pregnancy loss, or RPL) affects one to two percent of reproductive women. Recent studies suggest an association between vitamin D deficiency and auto- or allo-immunologic disruption in RPL. In one study, women who took vitamin D supplements (0.25 mcg twice daily) saw an increase of successful pregnancies. In fact, they had a continuing pregnancy rate of 70% compared to 55% in the control group. However, the study was small with just 40 women, and more research is needed. 

Vitamin D and egg quality

It’s unknown whether vitamin D supplementation affects egg quality, but there is a clinical trial being conducted that will hopefully provide more insights on the topic. Because vitamin D shows antioxidant properties, and has been shown to improve mitochondrial function of other tissues, it could become a treatment in the future. However, right now more research is needed.  

Vitamin D and AMH

One study looked at the impact of vitamin D supplementation on AMH levels for women with and without PCOS. AMH (Anti-Müllerian hormone) is an ovarian biomarker that may be used to assess a woman’s egg count. AMH levels can be two to three times higher for women with PCOS. 

The study found that vitamin D supplementation impacts AMH levels. For women with PCOS, AMH was decreased after vitamin D supplementation. For women without PCOS, AMH was significantly increased. 

Vitamin D and IVF

Healthy vitamin D levels are important during IVF. Multiple studies have found that vitamin D sufficient women undergoing IVF had higher implantation and pregnancy rates compared with the vitamin D deficient women. One study suggested that “Vitamin D supplementation could provide an easy and cost-effective way of improving pregnancy rates.” 

Vitamin D sufficient women undergoing IVF had higher implantation and pregnancy rates compared with the vitamin D deficient women.

This was confirmed in a meta-analysis of 11 studies of 2,700 women undergoing IVF. The researchers found that pregnancy and live birth was more likely in women with sufficient vitamin D status, compared to women who were vitamin D deficient or insufficient. 

Vitamin D to treat uterine fibroids

Uterine fibroids (also known as leiomyomas) are associated with infertility and misciarrage. Not to mention the symptoms of heavy bleeding and pelvic pain. Treatment options have traditionally been limited to surgical intervention, but that’s changing as new research is emerging that vitamin D supplementation could reduce the progression of fibroids. Read more about vitamin D and uterine fibroids.

Vitamin D and PCOS

Vitamin D deficiency is common among women with PCOS. One meta-analysis of 13 randomized controlled trials with 824 patients found that “vitamin D oral intake alone improved insulin resistance parameters and reduced inflammation in patients with PCOS.” Many doctors suggest vitamin D supplements for women with PCOS and vitamin D deficiency because it’s an inexpensive and safe treatment option. 

Vitamin D and endometriosis

Vitamin D intake may impact the risk of endometriosis. Low levels of vitamin D appear to be correlated to the onset and severity of endometriosis. And researchers have found women with the lowest levels of vitamin D also had the largest ovarian endometrioma, or ovarian cysts. Since vitamin D serves as an immunomodulator and anti-inflammatory agent, it makes sense that it can impact endometriosis from a biological standpoint. However, more research is needed to draw any conclusions.

Vitamin D and male fertility

The role of vitamin D in hormone production and sperm creation has been investigated in both animals and humans. Experimental studies support a beneficial effect of vitamin D on male fertility by playing a role in hormone production and by improving sperm parameters.

Clinical studies in humans regarding vitamin D and fertility have been controversial and more research is needed. Some studies have demonstrated a positive effect of vitamin D intake on semen quality and motility according to a literature review. Conversely, a study conducted with men specifically undergoing IVF demonstrated no correlation between vitamin D status and any fertility variables (motility, count, or morphology). 

Additionally, vitamin D may help with erectile dysfunction (ED). A significant proportion of erectile dysfunction (ED) patients have a vitamin D deficiency. Research shows that vitamin D supplementation may help delay the onset of ED—and may even restore normal sexual function to some men when coupled with positive lifestyle changes.

There’s no doubt vitamin D deficiency can lead to myriad fertility issues for both men and women. Determining whether there is a true vitamin D deficiency requires a blood test. It is relatively inexpensive and easily accessible. If you are diagnosed with a vitamin D deficiency, in general, it is a good idea to ensure adequate vitamin D intake to replenish levels for many reasons beyond fertility. As always, it’s important to talk to your doctor!

If you’re looking to up your vitamin D intake as a means of improving fertility, you might want to look into using ovulation tests to track your fertile window.


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