If you’re approaching or in the menopause transition, odds are you’re aware of the fact that sex hormones play a big role — and that progesterone is one of them.

But once you get into the weeds, things get, well, science-y. And confusing. Case in point: progesterone vs progestin. Is there a difference?

Continue reading for a full answer to this frequently asked question…

What is progesterone?

Progesterone is a naturally-occurring steroid hormone that plays a role in several of our body’s functions, most notably the menstrual cycle and pregnancy.

TL;DR: after ovulation, progesterone skyrockets. The goal: thicken the lining of the uterus to prepare the body for a potential embryo. If the egg is fertilized, the body releases even MORE progesterone to support the pregnancy.

If progesterone levels are too high, the result may be weight gain, mood symptoms (including depression), and fatigue. If too low, we may experience irregular periods, anxiety/depression, and headaches.

IMPORTANT: “May” is a key word here because these symptoms aren’t a guarantee. In fact, some women feel better with higher progesterone and are sensitive to a drop. Others are sensitive to progesterone period. In short, it’s not one-size-fits-all.

During perimenopause, progesterone starts to decline first, and the decline is STEEP. Estrogen follows the same course but fluctuates as it decreases — Jackie Giannelli, Founding Nurse Practitioner at Elektra Health, often tells her patients to imagine a ball going down a hill in San Francisco. Levels go up and down and up and down.

What is progestin?

Although the body produces progesterone itself, some people may need more of it for certain reasons. This is where progestins come into play.

Progestin is a synthetic (i.e. human-made) chemical that mimics the effects of progesterone in the body. It’s a form of progesterone used for a few reasons:

• Birth control
  As progestin-only or combined estrogen-progestin pills.
• Treating irregular menstrual periods
  Including amenorrhea (absence of a period) and abnormal bleeding.
• Fertility treatment
  To help regulate hormone levels during IVF of other assisted reproductive procedures.
• Gender-affirming therapy
  To help reduce gender dysphoria for trans women (individuals assigned male at birth but who live and identify as women).
• Menopause hormone therapy
  During the menopausal transition, the body’s production of two key female hormones, estrogen and progesterone, begins to fluctuate and progressively decline. Hormone therapy — formerly known as hormone replacement therapy or HRT — involves taking a supplemental form of either estrogen, or estrogen and progestogen together, to balance out and replace what the body is no longer producing.

Depending on use and dosage, progestin can come in the form of a pill, injection, gel/cream, suppository, or patch.

(Oh, and to add ANOTHER word to the vocab list…together, progesterone and progestins are called “progestogens.”)

Sooo…progesterone and progestin are not the same?

Nope! Progestin may have progesterone-like properties — and sound like progesterone — but it is technically NOT the same thing as this naturally-occurring hormone.

Some women tolerate progesterone better than progestins, while for others it’s the opposite. Confusing, we know. But the takeaway here is that it’s VERY individualized, and all decisions should be made alongside your women’s health provider.

Digging deeper into progestin use during menopause

Birth control

Many women are prescribed birth control pills as first line when they go to see their provider and say…”I’m experiencing symptoms of what I think is perimenopause. What can you offer?”

As Jackie explains, “a lot of times, birth control pills make sense. If you’re in early perimenopause, you are still ovulating. And if you are still ovulating, you can still get pregnant if you have a uterus. So a birth control pill for some is a great choice because it not only provides contraception but will help stabilize your cycle so you have a predictable period. It can help prevent uterine cancer and bone loss, and some people just like the predictability of knowing when they’re going to bleed. It can also help those who have irregular or heavy periods.”

Combination birth control pills contain both estrogen and progestin while the “minipill” is a progestin-only pill without estrogen.

Hormonal birth control can come in a variety of forms, including:

• Low-dose combination oral contraceptives
  Birth control pills that contain estrogen and progestin. The dose of hormones in a birth control pill is typically higher than those used for menopause hormone therapy (more on that below). The benefit of this dosing is suppression of hormonal fluctuations, which by themselves cause many perimenopause symptoms.
• Progestin-only pills
  Progestin-only pills that do not contain estrogen are taken daily and, over time, can result in lighter menstruation.
• Hormonal IUDs
  IUDs — or intrauterine devices — sit inside the uterus and release a small amount of progestin into the body over several years to prevent pregnancy and help with painful/heavy menstrual bleeding.

The dose of hormone in birth control is much higher than the dose in hormone therapy — it needs to be in order to override ovarian function, prevent ovulation, and provide contraception.

Menopausal hormone therapy

If eligible, hormone therapy is often the first line of treatment for several menopause symptoms — notably hot flashes/night sweats and osteoporosis. And it may have an indirect effect on a whole slew of other symptoms (acne, anxiety/depression, dry skin, joint and muscle aches, mood changes, sleep problems), although it’s typically not explicitly prescribed for them.

Estrogen-only therapy is commonly used for women who have had a hysterectomy, while combination therapy (estrogen and either natural progesterone or synthetic progestin) is used for women with a uterus.

Safety/side effects of progesterone vs progestin

While we do NOT have head-to-head studies comparing the breast effects — i.e. risk of breast cancer — between hormone therapy regimens with progestins versus progesterone, we DO know that there seems to be an increased risk of breast cancer in women using estrogen and a progestin versus estrogen alone. We also know that the risk of breast cancer did not go up in women using transdermal estradiol and micronized progesterone, although this is observational data and the study did not extend beyond five years.