Progesterone is a female sex hormone. It’s produced mainly in the ovaries following ovulation each month. It’s a crucial part of the menstrual cycle and maintenance of pregnancy.

Progesterone helps to regulate your cycle. But its main job is to get your uterus ready for pregnancy. After you ovulate each month, progesterone helps thicken the lining of the uterus to prepare for a fertilized egg. If there is no fertilized egg, progesterone levels drop and menstruation begins. If a fertilized egg implants in the uterine wall, progesterone helps maintain the uterine lining throughout pregnancy.

Progesterone is necessary for breast development and breastfeeding. It complements some effects of estrogen, another female hormone. It also works with testosterone, the precursor for adrenal hormones. Men produce a small amount of progesterone to help in sperm development.

Progesterone is important during childbearing years. If you don’t have enough progesterone, you may have trouble getting or staying pregnant.

After one of your ovaries releases an egg, your progesterone levels should rise. Progesterone helps the uterus thicken in anticipation of receiving a fertilized egg. If it’s not thick enough, the egg won’t implant.

Symptoms of low progesterone in women who aren’t pregnant include:

Low progesterone may cause abnormal uterine bleeding in women who aren’t pregnant. Irregular or absent periods may indicate poorly functioning ovaries and low progesterone.

If you get pregnant, you still need progesterone to maintain your uterus until your baby is born. Your body will produce this increase in progesterone, which causes some of the symptoms of pregnancy, including breast tenderness and nausea. If your progesterone levels are too low, your uterus may not be able to carry the baby to term.

During pregnancy, symptoms of low progesterone include spotting and miscarriage.

Low progesterone may indicate ectopic pregnancy. This can result in miscarriage or fetal death.

Without progesterone to complement it, estrogen may become the dominant hormone. This may cause symptoms including:

A progesterone test (PGSN) can help your doctor tell if your progesterone levels are too low. This is a simple blood test that doesn’t require any preparation.

The test may show why you’re having trouble getting pregnant. It can also confirm if you’ve ovulated. The PGSN test can be used to monitor hormone replacement therapy or the health of a high-risk pregnancy. Progesterone levels are usually higher than normal during pregnancy. They’re even higher if you’re having more than one baby.

Men, children, and postmenopausal women all have lower progesterone levels than women in their childbearing years. What is considered a “normal” progesterone level depends on a person’s age and gender. In women, other factors include whether you’re pregnant and where you are in your menstrual cycle. Progesterone levels fluctuate throughout the menstrual cycle. They peak about seven days before your period. And levels can vary during a single day.

Poorly functioning ovaries can cause poor progesterone production. And during menopause, it’s natural for estrogen and progesterone levels to fall.

You may not have any symptoms of low progesterone, and you may not need treatment. But if you’re trying to have a baby, hormone therapy could be useful. Hormone therapy increases progesterone levels and may help thicken your uterine lining. This may improve your chances of a healthy pregnancy and carrying to term.

Menstrual irregularities and abnormal bleeding can improve with hormone therapy. For severe symptoms of menopause, hormone therapy usually involves a combination of estrogen and progesterone. Women who take estrogen without progesterone are at increased risk of developing endometrial cancer.

Treatment options for progesterone supplementation include:

  • creams and gels, which can be used topically or vaginally
  • suppositories, which are commonly used to treat low progesterone that causes fertility problems
  • oral medications, like Provera

Hormone therapy (either estrogen only or a combination of estrogen and progesterone) may help ease symptoms such as:

For some women, progesterone improves mood. Oral progesterone may provide a calming effect, making it easier to sleep.

Hormone therapy may increase the risk of:

Your doctor will probably advise against hormone therapy if you have a history of:

  • breast cancer
  • endometrial cancer
  • liver disease
  • blood clots
  • stroke

Natural remedies for raising low progesterone levels include:

  • increasing your intake of vitamins B and C, which are necessary for maintaining progesterone levels
  • eating more foods with zinc, like shellfish
  • controlling stress levels, since your body releases cortisol instead of progesterone when you’re stressed

Progesterone is generally not supplemented in women who are experiencing menopausal symptoms of hormone imbalance. This is because menopausal symptoms are mostly caused by low estrogen levels.

Hormone replacement does carry some risks, so it’s important to discuss them with your doctor. There are prescription medications that are formulated to look the same to your body as your naturally occurring hormones. These are sometimes called “bioidentical hormones.” While these may sound more favorable, they have the same risks as other prescription formulations.

Low progesterone can cause different problems for men and women. However, there are treatments available that can help resolve low progesterone. Hormone therapy may be a long-term solution for some, particularly postmenopausal women.

Talk with your doctor about which treatment would be best. It may take a few weeks to see results from hormone therapy. And you can work with your doctor to reevaluate your treatment plan each year.