Progesterone

What is progesterone? Why is it important? What is progesterone deficiency?

Let’s break it down

I’m going to be very honest and transparent in saying that the misinformation around progesterone drives me crazy. What really frustrates me the most is that many of those people are selling progesterone supplements or courses. These are people who are calling themselves hormone experts when they truly are not. I commonly see women with PCOS get diagnosed with low progesterone get put on a progesterone supplement while she is trying to conceive. This is affectively giving her contraception so she will not conceive. Let’s remind ourselves what progesterone is and why it is so important.

The ovaries and menstrual cycle

You have probably heard my analogy about the vault, but let’s start with that just in case you haven’t. All the eggs you are ever going to have are kept inside a vault in your ovary. Each month a group of eggs is released and each egg grows inside a follicle. The ovary is a hormone making factory. The hormone of choice is estrogen. In a normal cycle the brain sends out follicle stimulating hormone called FSH which stimulates a follicle to grow. As the follicle grows, it makes estrogen. The brain waits for an estrogen level to be high enough for long enough to sense there is a mature follicle. Then LH is sent out which is the trigger or surge to induce ovulation. Ovulation is when the egg inside the follicle finalizes the last stages of meiosis and is released. Then fluid comes out along with the egg and is swept into the fallopian tube. If you are trying to get pregnant you have 24 hours to have the egg be fertilized and ovulation happens about 36 hours after the LH surge. Next is when progesterone comes in the picture. Progesterone does not exist until you have ovulated. This is called the luteal phase. I see so many women diagnosed with progesterone deficiency and find out that it was tested outside of the luteal phase. It’s supposed to be low at that time. This is normal.

The Luteal Phase

If you have a normal cycle, the first 14 days are your follicular phase and the second 14 days is called your luteal phase. This is when your progesterone should be high. Progesterone is essential for pregnancy. So LH is released in pulses and stimulates the corpus luteum to make progesterone until the placenta takes over and you get pregnant. The corpus luteum is a cyst from the follicle that grew in the follicular phase. When it released the egg it became a yellow fatty structure that now makes progesterone. This cyst looks different than the follicle. Side note: This means that cysts in the ovary are normal findings throughout the menstrual cycle. So the corpus luteum begins to send out pulses of progesterone which means that your progesterone levels are NOT going to be steady. It will go up and down. However, there are normal thresholds that we look for to know that you ovulated. We test your levels about a week after ovulation and it should be at least 3 nanograms per milliliter. It will range from 3-40 depending on when it is checked. If you get pregnant that pregnancy will implant and HSG will be made from the pregnancy. This HSG is similar to LH and it also stimulates progesterone production from the corpus luteam. We call this rescuing the corpus luteam because it will die in 14 days if there is no pregnancy. If your corpus luteam dies, you will have a period. If you are not ovulating or making progesterone there is no progesterone drop and you do not have a period. However, you can sometimes have breakthrough bleeding or abnormal bleeding from prolonged low levels of estrogen exposure. This is common in people with PCOS. However, a period is truly a drop in progesterone levels.

Implantation

Timing of progesterone is essential. If you have gone through IVF or embryo transfer, you know we are crazy about progesterone. Egg and sperm fertilize in the fallopian tube and it takes 5-6 days for the embryo to make its way into the uterus where implantation occurs. Implantation typically takes place on the 6th day of progesterone exposure. The implantation window means there is a narrow window inside the uterus where that lining has gone to a compacted stage. During this window of 5-7 days of progesterone, the lining could accept a pregnancy. If you have an embryo in the uterus and do not have enough progesterone, the embryo will not implant. If you have an embryo in the uterus and there has been too much progesterone, it will not implant. Your body is dependent upon the corpus luteum making the progesterone until implantation happens and the placenta takes over. The corpus luteum is essential for implantation to occur. So if you have to have it removed, you will need to take progesterone pills, suppositories, or injections until the placenta takes over at about 9-10 weeks.

PCOS

When someone says PCOS is caused by low progesterone levels or by taking progesterone in birth conrol pills for too long, they are wrong. Yes, those levels are low when you have PCOS. No, you do not need to take progesterone supplements. No, your birth control did not cause your PCOS. PCOS is when you have a lot of eggs inside the vault and are released every month. The cause is partially genetic and epigenetic and your exposures, environment, weight, etc. When your ovary has so many small follicles making estrogen and your brain sends out FSH, it gets diluted and not of them are strong enough to respond. No egg grows. You don’t get the peak estrogen level or trigger the LH surge. Therefore you do not ovulate or make progesterone. At least not at regular intervals. Sometimes a prolonged FSH exposure will get a follicle to ovulate but typically irregular periods are the hallmark of the disease. Since the ovary is a hormone producing factory and it can’t make estrogen or progesterone. It shifts gears and starts making androgens so LH starts constantly going up. Because there is no corpus luteum, it stimulates other cells in the ovary to start making androgens like testosterone. This may cause acne and hair growth. Something else that happens is your endometrium is exposed to low level estrogen and never gets the signal to bleed. So now you have cells inside the uterus that just sit there. These cells can turn into cancer which is one of the worst outcomes. So a treatment of PCOS is to protect the endometrium and giving progesterone supplementation. If you are trying to ovulate, you will get a ovulation induction medication like Clomid or Letrozole so you can get pregnant. An option for women not getting pregnant is constant progesterone supplementation whether it’s a shot, implant, or IUD or daily birth control. The best part about birth control is that it can help with the high levels of testosterone. It cannot reverse the disease and when you stop the pill you will go back to your normal state. The pill did not cause your PCOS, it was treating the disease, which is very important to note.

That was a lot of information so I will stop there. In the next blog post, I will dive into luteal phase deficiency.