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  • Writer's pictureDr. H. Singh, ND

How much Progesterone is needed to help Protect a Pregnancy and Reduce Miscarriage Rates?

The research behind progesterone and its impact during fertility treatments and early pregnancy has been growing over the last decade. We continue to see more studies evaluating for the efficacy of different types of progesterone supplementation: oral pills, vaginal suppositories, or intramuscular injections. What we are seeing is a clearer comparison where some forms of progesterone may be more beneficial over others. And we are still learning if and how progesterone might help support pregnancy.

A new systematic review looked at multiple trials of patients going for a Frozen Embryo Transfer (FET) and did an analysis of these cohort studies to help determine if there was an optimal range of progesterone for these patients to help support early pregnancy.

This systematic review of the research on took in to account studies that included patients going for a FET with a blastocyst and using exclusively vaginal progesterone suppositories. This means that patients using intramuscular progesterone injections or oral progesterone pills were excluded from the review.

While this review establishes association/correlation and not causation, taken in to account with various other trials over the last few years, we are clearly seeing a valuable role for progesterone and its role in supporting pregnancy. Vaginal progesterone suppositories in particular appear to provide better efficacy and have a more clear safety profile during pregnancy compared to other forms of progesterone.

Does Progesterone Increase the Chances of Becoming Pregnant?

The systematic review published in 2021 in the medical journal Fertility and Sterility found that having a progesterone value above 10 ng/mL (equivalent to 31.8 nmol/L for Canadians) had a 31% higher likelihood of achieving a clinical pregnancy.

This may be because patients who were pregnant simply had higher progesterone production or it may point to an optimal level of progesterone to help support early pregnancy. Further clinical studies are required to help understand this as this research paper does not necessarily establish causation.

Can Progesterone Increase the Chances for a Successful Pregnancy?

The new systematic review published this year (2021) found that patients who had a progesterone level above 10 ng/mL (equivalent to 31.8 nmol/L for Canadians) had 47% increased likelihood of carrying to term and continuing on to give a live birth.

Can progesterone reduce the risk of a miscarriage?

The recently published review found that patients that had a progesterone levels above 10 ng/mL (equivalent to 31.8 nmol/L for Canadians) 38% less likely to miscarry compared to patients that had progesterone levels above this threshold.

What type of progesterone is best for Fertility?

This study exclusively included patients that used vaginal progesterone suppositories. In fact, a lot of the newer studies evaluating for efficacy of progesterone to support early pregnancy and help reduce the risk of miscarriage for patients that experienced previous miscarriages are also using vaginal suppositories for progesterone.

Is progesterone safe during pregnancy?

We are seeing more research help establish which forms of progesterone may be safer for both Mother and Baby. In addition, the optimal dose can vary and this needs to be discussed with your licensed healthcare provider. However, latest studies are finding that certain forms of progesterone used in recommended doses may have much more benefit than risk as they may help to reduce the risk of miscarriages, particularly in patients who have experienced a miscarriage in the past.


  1. Melo, P., Chung, Y., Pickering, O., Price, M. J., Fishel, S., Khairy, M., Kingsland, C., Lowe, P., Petsas, G., Rajkhowa, M., Sephton, V., Tozer, A., Wood, S., Labarta, E., Wilcox, M., Devall, A., Gallos, I., & Coomarasamy, A. (2021). Serum luteal phase progesterone in women undergoing frozen embryo transfer in assisted conception: A systematic review and meta-analysis. Fertility and Sterility.

This article is in no way a replacement for medical advice or medical care, it is advised that anyone concerned about their Reproductive Health & Fertility should speak with their licensed Naturopathic Doctor. Please discuss with your healthcare provider first and only make changes to your medications or treatment plan if recommended by your healthcare provider and under his/her guidance.

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