Related Articles
Low progesterone can have different effects on women, depending on whether they are pregnant or not. Learn about symptoms and causes
Low progesterone can have different effects on women, depending on whether they are pregnant or not. Pregnant women need progesterone to maintain their uteruses until the baby is born.
Symptoms in women who are not pregnant
- Irregular periods or missed periods (the most common symptom).
- Premenstrual spotting
- Abnormal uterine bleeding
- Severe headaches or migraines migraine with no prior history
- Anxiety, depression, and other mood changes
Symptoms in pregnant women
- Spotting
- Ectopic pregnancy caused by an error in implantation
- Miscarriage or fetal death
- Infertility
Low progesterone levels can cause estrogen to become the dominant hormone, which can lead to:
- Heavy bleeding, irregular menstrual cycles, PMS
- Weight gain
- Gallbladder problems
- Decreased sex drive
- Tender breasts
- Fibroids
- Hot flashes
- Endometriosis
What is progesterone?
Progesterone is a female sex hormone that is secreted by part of the ovary called the corpus luteum. During the menstrual cycle when ovulation occurs, the vestiges of the ovarian follicle containing the developing egg are discharged from the ovary and form the corpus luteum.
The main functions of progesterone include regulating your menstrual cycle and keeping them regular. During the early stages of pregnancy, progesterone aids in creating a favorable environment for a fertilized egg. When progesterone levels are low, menstrual cycles can become irregular, or fertilized eggs may have difficulty developing and growing
Progesterone is commercially available in the form of progestins, which are synthetic steroid hormones with progesterone-like characteristics. Progestin is frequently combined with estrogen in the production of contraceptives such as birth control pills and skin patches. Progestin can also be used to alleviate symptoms such as irregular periods, vaginal dryness, and night sweats.
Progesterone is also secreted in men in limited amounts and plays a role in sperm development.
What role does progesterone play in menstruation and pregnancy?
Progesterone prepares the uterus for pregnancy:
- After ovulation, progesterone prepares the endometrium for the possibility of pregnancy. Secretion of the hormone causes the uterine lining to thicken in preparation for a fertilized egg, promotes the growth of more blood vessels, and signals the glands within the endometrium to secrete nutrients to nourish the embryo.
- Progesterone prevents the body from rejecting an egg due to uterine muscular spasms. The body will not ovulate if it is producing excessive amounts of progesterone.
- Progesterone then helps maintain the endometrium all throughout pregnancy. As it is produced by the corpus luteum, it prepares the uterine tissue lining for the fertilized egg to implant and is fundamental for developing the placenta.
- When the placenta matures, it begins to secrete progesterone, which helps sustain the corpus luteum. This helps maintain high levels of the hormone throughout pregnancy and prevents the body from producing new eggs. It also aids stimulating the breasts to produce milk.
- If an egg is not fertilized, the corpus luteum breaks down, reducing progesterone levels in the body. This transition triggers menstruation, during which the egg disintegrates and the uterine lining sheds, preparing the body for the next menstrual cycle.
What are normal levels of progesterone?
Progesterone levels are usually quite low before:
- Menstrual cycle begins
- Ovulation
After or during ovulation, progesterone is the dominant hormone, complemented by estrogen. Progesterone is high around this time, and levels vary among women depending on whether they are pregnant.
Serum progesterone levels are measured in nanograms per milliliter (ng/mL). Normal progesterone levels (in ng/mL) should be as follows:
- Beginning of the menstrual cycle: 1
- After menopause: 1
- During the menstrual cycle: 5-20
- First trimester of pregnancy: 11-90
- Second trimester of pregnancy: 25.5-89.5
- Third trimester of pregnancy: 42.5-48.5
Any values within these measurements with slight fluctuation are considered safe and healthy.
What causes low progesterone levels?
Systemic imbalances may cause low progesterone secretion:
- Polycystic ovary syndrome: During ovulation, when the ovaries do not release an egg, there is no empty follicle to create progesterone. This is called an anovulatory cycle, which is frequently observed in women with polycystic ovary syndrome (PCOS) who may have hormonal imbalances that hinder ovulation. If you think you could have PCOS or are having anovulatory cycles, you should see your doctor.
- Hypothyroidism: Hypothyroidism occurs when the thyroid gland produces insufficient T3 and T4 hormones that regulate the entire endocrine system. Your body is only able to make enough progesterone with the help of these hormones. Thus, your body may struggle to create progesterone if you don't get enough T3 and T4.
- Stress: Inadequate cortisol levels may cause depletion of progesterone. Cortisol is a stress hormone that is produced together with progesterone during hormone synthesis. Cortisol and progesterone are made up of the same chemical composition. When your body is under a lot of stress and needs extra cortisol, it will take progesterone from your reproductive system to make up the difference. This leads to a dip in your progesterone levels.