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Structural formula of Progesterone

What is progesterone?

Progesterone is one of the steroid hormones that plays a role in the menstrual cycle and early stages of pregnancy. It is secreted by the corpus luteum, a temporary endocrine gland that females produce in the second half of the menstrual cycle. Progesterone also plays a role in sexual desire. Low levels of progesterone can cause some serious difficulties in conception and during pregnancy. 

How does progesterone work?

During the menstrual cycle, when the egg is released during ovulation, the other ovarian follicles that enclosed a developing egg form a structure called the corpus luteum. This releases progesterone that prohibits muscle contraction in the uterus that would cause the body to reject an egg. High levels of progesterone prevents the body from ovulating. 

The uterine cycle and hormone levels of the menstrual cycle

If the egg is not fertilized, the corpus luteum breaks down which lowers the progesterone levels in the body. In the case of pregnancy, progesterone stimulates the blood vessels in the endometrium that will feed the early embryo. Progesterone creates an environment for a fertilized egg and prepares the tissue lining of the uterus to allow the fertilized egg to implant. In the early stages of pregnancy, the corpus luteum continues to produce progesterone and establishes the placenta. Once the placenta is developed, it takes over the progesterone production around 8-12 weeks. Progesterone also prepares the breasts for lactation. 

Potential problems with progesterone production

Woman looking at a pregnancy test

High progesterone levels are believed to be partly responsible for PMS symptoms like breast tenderness, mood swings, and feeling bloated*.

In pregnancy, the level of progesterone increases, therefore, low production of progesterone may cause complications. 

People with low levels of progesterone often have heavy menstrual bleeding or may face difficulties in conceiving as there is not an appropriate amount of progesterone to set the environment for a fertilized egg to grow. Low progesterone levels can cause a miscarriage or a preterm delivery*. 

Symptoms of Low Progesterone
  • Irregular periods
  • Abdominal pain during pregnancy
  • Frequent miscarriages
  • Spotting during pregnancy


Progesterone lab test

Progesterone products are available over the counter which women use to treat PMS symptoms or abnormal uterine bleeding*. Progesterone is also used in combination with estrogen as part of hormone replacement therapy and for treating menopausal symptoms

Progesterone injections are used to treat infertility*. Some people may experience side effects like loss of appetite, weight gain, upset stomach, water retention, headache, fever, allergies, drowsiness or insomnia. 

Hormone Testing Available

Fantastic affordable blood spot, saliva, and saliva + blood test kits

At Coast to Coast Compounding we can provide you with an at-home testing kit which allows you to test your own hormone levels. Speak with one of our knowledgeable pharmacists or your healthcare provider for more information on using one of these testing kits. Click here for more information on how to get your hormones tested.


You should always consult your health care provider before starting any herbal supplements or products.   *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.