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  • Dr. Singh, ND

Bio-Identical Progesterone Therapy for Fertility

bio-identical hormone therapy, progesterone, estrogen, fertility

Progesterone is the main reproductive hormone produced in the second half of the cycle after ovulation occurs. When fertilization occurs, progesterone has many vital functions to help support implantation of the embryo in to the uterine lining and to help keep the pregnancy viable.

From conception up until about week 9 of pregnancy the corpus luteum (the remnant of the ruptured follicle from the ovary) is responsible for producing progesterone. From week 5 to about week 9 there is a gradual transition where the placenta takes over the responsibility to continue producing progesterone to support the pregnancy as the corpus luteum deteriorates. The importance of progesterone from the corpus luteum has been established from various studies showing that removal of the corpus luteum before week 7 of pregnancy results in a spontaneous abortion.

Most Women are able to produce sufficient amounts of progesterone in the second half of the cycle and the first few weeks of pregnancy, however, a small subgroup of Women (estimated to be around < 10%) have what is known as a luteal phase defect. This means that during the luteal phase there is a suboptimal level of progesterone being produced, and this has negative consequences on fertility. In these cases the use of Bio-Identical Progesterone may prove to be quite beneficial.

Testing for Luteal Phase Deficiency

Hormone testing has consistently been shown to be a poor method to evaluate to true progesterone levels. The reason for this is the pulsatile nature of progesterone secretion from the corpus luteum. For example, within the span of about 2 hours the progesterone level can fluctuate by about 10x the concentration from baseline.

Various reviews and studies recommend against the use of blood tests to screen for at-risk pregnancies due to luteal phase defect. The most objective method to evaluate for for a luteal phase defect is measuring the length of the luteal phase. If the luteal phase is < 13 days, then this is the most reliable criterion to diagnose a luteal phase deficiency.

Treatment for Luteal Phase Defects

Luteal phase defects are usually classified as a subcategory of ovulation dysfunction. So treatment should include interventions to support healthy ovulation. Additionally, Women with luteal phase deficiency would benefit from using additional progesterone supplementation, either in the form of a transdermal cream or ideally a suppository (this helps deliver higher concentrations of progesterone to the uterus). The progesterone can help support implantation of the embryo and help prevent spontaneous abortion that might result from low progesterone levels. This should be considered in natural cycles where conception is attempted for all Women with luteal phase defects.


When a medicated cycle is attempted with the use of long-acting or short-acting protocols to stimulate or suppress, respectively, hormone production from the pituitary gland in the brain, there is a certain level of luteal phase deficiency that is induced in the second half of the cycle after the transfer is performed. Women that undergo these procedures benefit from progesterone supplementation for at least 2 weeks after transfer, and in some cases up until week 7-10 of pregnancy. The use of progesterone after these procedures has been shown to help positive pregnancy rates.

This article 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 or Primary Care Provider.


1. Progesterone supplementation during the luteal phase and in early pregnancy in the treatment of infertility: an educational bulletin. (2008). Fertility and Sterility, 89(4), 789-792.

2. Hill, M. J., Whitcomb, B. W., Lewis, T. D., Wu, M., Terry, N., Decherney, A. H., . . . Propst, A. M. (2013). Progesterone luteal support after ovulation induction and intrauterine insemination: a systematic review and meta-analysis. Fertility and Sterility, 100(5).

3.Shapiro, D., Boostanfar, R., Silverberg, K., & Yanushpolsky, E. H. (2014). Examining the evidence: progesterone supplementation during fresh and frozen embryo transfer. Reproductive BioMedicine Online, 29.

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