Progesterone is a female steroid hormone produced by the ovaries and adrenal glands, or primarily by the placenta during pregnancy. This hormone is most well known for its role in regulating the menstrual cycle and in maintaining a pregnancy. However, like other steroid hormones, progesterone also affects the function of all parts of the body, including the brain and nervous system, heart and circulatory system, reproductive organs, immune system, digestive tract, bones and liver.

Common Symptoms

Women can start experiencing a progesterone deficiency as early as their 20s. Some of the main signs are belly-centric weight gain, low libido, irregular or heavy periods, infertility and difficulty maintaining a pregnancy. C.W. Randolph, M.D., co-founder of the Natural Hormone Institute, says that women with low progesterone may also experience lumpy breasts that are painful to the touch, severe premenstrual symptoms of bloating, moodiness, cravings and pain, or especially severe hot flashes and irritability during perimenopause and menopause.

Fatigue, Pain and Depression

Women with a progesterone deficiency are also plagued by extreme mental and physical fatigue. This is because low levels of the hormone cause insomnia and hinder the function of the energy-producing organs, like the adrenals and thyroid. Another key sign of a progesterone deficiency is pain, including frequent headaches, joint and muscle aches even when there has been no physical exertion, or fibromyalgia, a condition characterized by body-wide pain and sensitivity to touch. Dr. Randolph explains that this is because a progesterone deficiency has been linked with over-activity of pain receptors, as well as abnormally low production of the body’s natural painkillers, the endorphins. Low progesterone has also been linked to insufficient production of the feel-good neurotransmitter serotonin, triggering depression, postpartum depression or anxiety.

Serious Long-term Effects

Some common signs of a progesterone deficiency that may not be immediately noticeable include chronic constipation and getting sick often, since the hormone plays a role in intestinal health and overall immunity, explains Dr. Randolph. Women with a long-term progesterone deficiency are also at increased risk of osteoporosis, heart disease and breast and uterine cancers.