Progesterone: The Quiet Powerhouse Hormone You’ve Been Overlooking

We talk a lot about estrogen. It seems to be the sister in the spotlight, the one who gets all the attention. But what about that other hormone?

I’m talking about progesterone.

It's the quiet sister. The one who’s working quietly. Less attention, but no less important.

Let’s talk about it.

What is progesterone?

Progesterone is a steroid hormone. What does that mean? Steroid means it’s structure is derived from cholesterol (yes this is part of why we NEED cholesterol) and hormone means it's a molecule that travels throughout the body, leading to actions in distant organs and cells.

It’s made in our ovaries, in the corpus luteum (the cyst in the ovary after ovulation) and by the placenta in pregnancy.

The term progesterone is named from the Latin pro meaning for and gestatio meaning pregnancy.

What does progesterone do in the body?

This is a loaded question and one still being investigated but we know a lot about progesterone.

• Ovulation

  • helps promote follicular growth, can reach 10,000x higher concentration as the follicle matures (this is what will ovulate)

  • the dominant follicle will secrete progesterone

  • The corpus luteum (the cyst left behind after ovulation) secretes progesterone (during the luteal phase of the cycle)

    
    

• Pregnancy, Lactation

  • progesterone will start to be made by the pregnancy and the placenta toward the end of the first trimester

  • Formed from mom’s LDL cholesterol (often referred to as "bad" cholesterol)

  • The rapid decrease in progesterone after delivery initiates secretion of breast milk

    
    

• Brain

  • the breakdown products of progesterone act on GABA receptors in the brain, responsible for relaxation/sedation (This is why it helps with sleep!)

  • Called a “neurosteroid” meaning a steroid very active in the brain

  • Progesterone receptors found in areas for cognitive function and emotional processing

  • Of note, new pharmaceuticals for the treatment of postpartum depression are synthetic versions (brexanolone) of a progesterone compound (allopregnenolone)

  • Animal models of Alzheimer's disease show improvement with hormone therapy, including progesterone

    
    

• Immune system

  • part of the above brain benefit is due to anti-inflammatory effect

  • Pregnancy itself is an immune event: the fetus is a foreign graft but must be recognized and protected; progesterone plays a role in that

  • promotes anti-inflammatory molecules

    
    

For an added bonus, progesterone is active in males as well. It plays a role in their sperm

action.

Who needs progesterone?

In training as an obgyn, I was taught that estrogen cannot be given alone to someone with a uterus, it must be balanced with progesterone. This is because estrogen and progesterone affect each other's receptors inside the uterus, estrogen promoting growth which cannot go unchecked.

There are also newer medications that can be used for this balance in place of progesterone.

While it is true that someone without a uterus doesn't need progesterone for uterine protection, she can have progesterone. She certainly can take it and reap the benefits.

What can progesterone be used for?

Some of the clinical uses of progesterone:

• Early pregnancy support in someone with a history of recurrent loss

• Shortened cervix

• Preterm labor (this was standard practice when I was in training, has fallen out of favor)

• Mood, postpartum depression

• Heavy periods

• Sleep

• Hot flashes, night sweats in perimenopause or menopause

  
  

Are there side effects or down sides?

If not menopausal, progesterone imbalances can lead to spotting between periods.

There is something called progesterone intolerance which means some of the intended effects actually have the opposite effect for some patients. Mainly, the relaxation effect can be the opposite. This is not well-documented in medical literature but is discussed anecdotally.

How is it given?

In my practice, I prescribe bio-identical hormones. These can also be compounded. Compounding MUST be used if someone has an allergy to peanuts, as the prescription progesterone is suspended in peanut oil.

Micronized progesterone is the bio-identical version, it is micronized and suspended in oil because progesterone is otherwise not absorbed well when taken orally.

Patients typically take this as a capsule in the evening because of its benefits to sleep.

Remember this is a hormone that comes from cholesterol. This is part of why we NEED

cholesterol.

Resources:

https://pmc.ncbi.nlm.nih.gov/articles/PMC9322133/

https://pmc.ncbi.nlm.nih.gov/articles/PMC7432434/

https://pubmed.ncbi.nlm.nih.gov/18027076/