The harmony of the menstrual cycle and other aspects of women’s health is attributed to the two major female hormones produced in the ovaries – oestrogen and progesterone. Progesterone, with its vital role in milk secretion and preparing the uterus for fertilization, is a common test to assess fertility.
The levels of progesterone change throughout the menstrual cycle, peaking around the middle of the cycle. The primary role of progesterone in a non-pregnant female is to increase the thickness of the uterus wall and promoting secretory function to prepare for fertilization. In a pregnant woman, progesterone plays a part in developing breast tissues and glands to prepare for lactation.
Although progesterone is largely a female hormone, men also have smaller amounts of it in their blood. In men, progesterone likely takes part in producing sperms.
Normal Levels of Progesterone
Since this hormone waxes and wanes throughout the month, its normal levels are also variable.
The normal level of progesterone at the beginning of the menstrual cycle (1st day) is less than 1 ng/ml. At about the time of ovulation (14th day), it is 5-20 ng/ml.
In pregnancy, the levels of progesterone progressively increase peaking in the third trimester.
- First trimester: 11.2 – 90 ng/ml
- Second trimester: 25.6 – 89.4 ng/ml
- Third trimester: 42.5 – 48.4 ng/ml
Immediately after the termination of pregnancy (childbirth or abortion), the level of progesterone rapidly falls. In men and menopausal women, progesterone is 1 ng/ml or less.
Why Are Progesterone Levels Tracked?
The level of progesterone in your blood can give clues to multiple underlying conditions including your fertility status. Progesterone levels is a routine test ordered by doctors if you have trouble conceiving. Progesterone levels and uterine thickening are measured at the 21st day of your menstrual cycle to test for the fertility status. Sometimes, these levels are tested to track ovulation and to plan conception accordingly.
Apart from infertility, progesterone can also be a cause of abnormal vaginal bleeding. The level of this hormone is sometimes measured to find out the cause of the abnormal bleeding.
In a pregnant female, the level of circulating progesterone can be useful to identify high-risk pregnancy and risk of miscarriage.
What Does a High Progesterone Level Mean?
When the level of progesterone comes out higher than the normal range, it can mean a number of things. Pregnancy is the most common and physiological cause of a high progesterone level, but the pathology of the ovaries can result in spiking as well.
Studies have shown that ovarian cysts and certain types of cancers of the ovaries can cause progesterone levels to rise. Further investigations are required to come to a conclusive diagnosis.
High progesterone levels can also sometimes point to an underlying disorder of the adrenal glands.
What Does a Low Progesterone Level Mean?
Lower than normal levels of this important hormone can have different implications. The most important complication of low progesterone is a failure in ovulation. Low progesterone which results in ovulation problems is one of the common factors in infertility. If low progesterone is the cause of your infertility, it can usually be easily treated.
When this level is lower than normal in a pregnant woman, it could point to a miscarriage or an ectopic pregnancy, both of which need to be investigated further.
How Are Abnormal Levels of Progesterone Treated in Childbearing Women?
For women who are at childbearing age, abnormal progesterone can be treated by hormone therapy. Hormone therapy can increase progesterone levels and may facilitate uterine thickening. This could increase the chances of getting pregnant or maintaining a healthy pregnancy.
How Are Abnormal Levels of Progesterone Treated in Post-menopausal Women?
Women experience menopause where they are no longer able to conceive naturally. This occurs between 45 to 55 years of age, while 10% of women experience early menopause before 40 years old. During this period, the body stops producing female hormones including progesterone. The hormone imbalance can cause various menopausal symptoms such as hot flushes and vaginal discomfort, which can be relieved by post-menopausal hormone replacement therapy. However, post-menopausal hormone replacement therapy has its fair share of risks and benefits. According to studies, being on combined oestrogen and progestin (a synthetic form of human progesterone) hormone replacement therapy increases a post-menopausal woman’s risk of getting breast cancer. As such, it is important to discuss the risks of hormone replacement therapies with your doctor.
The Bottom Line
If you’re having trouble getting pregnant, it is a good idea to get your progesterone levels checked. The level of this hormone is a reliable indicator of fertility and ovulation. Your doctor can also order additional tests including other hormones such as oestrogen, FSH and LH to check your fertility status. If you are having symptoms of approaching menopause, is it also recommended to go through hormone blood tests. Hormone replacement therapy in menopausal women is highly beneficial in treating hormone imbalance and menopausal symptoms. However, it is important for doctors to evaluate and tailor the therapy to each individual to ensure that its benefits offset its risks.