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  • Writer's pictureDr. H. Singh, ND

Deficiency of this One Vitamin is Associated with Twice the Risk of Miscarriage

When it comes to miscarriage risk prevention we have to consider preconception care. Over the years more research has shed light on how lifestyle, diet, preconception health can predispose or reduce the risk of miscarriage for patients. When we support patients who are dealing with recurrent pregnancy loss (RPL) and there is no identifiable cause, we need to start digging a bit deeper to these modifiable risk factors to determine if we can help identify potential cause(s) for the recurrent miscarriages.

A new research paper published in the Journal of Fertility and Sterility in 2022 published data collected from 10 different research papers (4 randomized clinical trials and 6 observational studies) and found that deficiency in a particular vitamin was associated with an increased risk for miscarriage.

How much does Vitamin D status affect miscarriage risk?

The data indicated that patients who were deficient in Vitamin D (levels < 50 nmol/L) had a 94% increased risk of miscarriage when compared to patients who had Vitamin D sufficiency (levels > 75 nmol/L). Patients with Vitamin D insufficiency (levels 50-75 nmol/L) and/or Vitamin D deficiency had a cumulative 60% increased risk of miscarriage when compared to patients with Vitamin D sufficiency.

What does Vitamin D do?

Vitamin D has an important role in hormone production (steroidogenesis), including sex hormone production, modulating immune system activity, mineral metabolism and bone growth. It has been shown to affect symptom severity and cycle regularity in patients with polycystic ovarian syndrome (PCOS) as well. The exact mechanism by which Vitamin D may impact risk of miscarriage is still unclear.

What are the limitations of this research?

Limitations of this study are that it can only establish correlation and not causation. For example, patients with Vitamin D sufficiency may spend more time in the sun and may be more physically active, or they may be more likely to take other antioxidants like Vitamin E or Vitamin C and this may impact oxidative stress levels and antioxidant levels. These are what are referred to as confounding variables.

Is Vitamin D recommended to everyone trying to conceive or having recurrent pregnancy loss?

However, considering the easy accessibility to Vitamin D blood testing, cost effectiveness of treating Vitamin D deficiency and in light of available research highlighting the role of this Vitamin with other aspects of fertility (implantation, hormone production, sperm health, etc.) it makes sense to discuss this with your licensed Naturopathic Doctor.

How do I know what dose of Vitamin D is best for me?

Instead of just supplementing with Vitamin D, it is advisable to check blood levels because absorption of this Vitamin is quite variable depending on one's gut health and diet. For example, one individual may take a fraction the dose of Vitamin D as another and have more than double the levels on a blood test. Therefore supplementing with Vitamin D does not directly indicate that one may have sufficient levels. Especially if you are planning on taking Vitamin D supplements over an extended period performing a simple blood test can help prevent overdosing with Vitamin D and preventing Vitamin D toxicity/hypervitaminosis D (associated with kidney stones, seizures, hypercalcemia), calcifications in blood vessels and more).

This article is being shared as educational content and is in no way a replacement for medical advice or medical care, it is advised that anyone concerned about their Health should speak with their Naturopathic Doctor. Please discuss with your healtcare provider and only make changes to your medications regimen if recommended by your doctor and under their guidance and supervision.


  1. Tamblyn, J. A., Pilarski, N. S. P., Markland, A. D., Marson, E. J., Devall, A., Hewison, M., Morris, R. K., & Coomarasamy, A. (2022). Vitamin D and miscarriage: A systematic review and meta-analysis. Fertility and Sterility.

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