Updated by the Progyny Clinical Team — July 2025.
Progesterone is a hormone mainly made in the ovaries. It’s produced by the corpus luteum, which forms after an egg is released. This hormone helps prepare the uterus for an early embryo, which is a fertilized egg that has started to develop, to attach.
If the egg attaches, progesterone helps keep the lining of the uterus thick and healthy to support the pregnancy. Later in pregnancy, the placenta also makes progesterone to help maintain it.
Testing your progesterone levels
This test checks the amount of the hormone in your blood on the day of the test. If you’re having trouble getting pregnant or going through fertility treatment, your OBGYN or reproductive endocrinologist may check your levels to see if you’ve ovulated.
They might also test your levels if you’ve had a miscarriage, stillbirth, or unusual bleeding, since this hormone plays an important role in supporting a healthy pregnancy.
If your levels are low and you’ve had a miscarriage, your doctor may give you progesterone supplements in a future pregnancy once the pregnancy is confirmed. These supplements may help lower the risk of another miscarriage by creating a better environment in the uterus.
Understanding progesterone levels
These levels go up after you ovulate and are highest about five to nine days later. This happens during the second half of your menstrual cycle, called the luteal phase. Because of this, progesterone is usually checked six to eight days after ovulation — around day 21 if you have a 28-day cycle. If the egg isn’t fertilized, levels start to drop after this peak.
- If your level is elevated within a certain range during the luteal phase, it likely means you are ovulating.
- If your level isn’t elevated, it can mean that you’re not ovulating.
- If your menstrual cycle is irregular, you may be asked to come in for several blood tests until your period begins. This can pinpoint when ovulation occurs and ensures an accurate test result.
What contributes to low progesterone levels?
There are several factors that may be behind the low levels:
- Ovarian insufficiency
- Obesity
- Insulin resistance
- Polycystic ovary syndrome
- High stress levels
- Poor diet
- Lack of exercise
What causes higher progesterone levels?
Higher levels can be caused by various conditions, such as:
- Pregnancy
- Benign ovarian cysts
- Ovarian cancer
- Adrenal cancer
- Congenital adrenal hyperplasia
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Disclaimer: The information provided by Progyny is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider for medical guidance.