The corpus luteum is a structure that forms in the ovary shortly after the fertile window. Its main function is to produce progesterone, which helps thicken the endometrium and prepare it for embryo implantation if fertilization occurs.
The corpus luteum forms during the final stage of the menstrual cycle, known as the luteal phase. This phase usually lasts about 14 days and ends with menstruation if fertilization and implantation do not occur.
If menstruation has not started after about 16 days, pregnancy may be possible. In that case, it’s best to monitor for early signs of pregnancy, take a pregnancy test, and consult an OBGYN or other women's health provider for confirmation and guidance.
Purpose and function
The corpus luteum serves to:
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Produce progesterone and estrogen.
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Increase the thickness of the uterine lining.
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Stimulate increased blood vessel formation in the endometrium.
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Support embryo implantation if fertilization occurs.
The corpus luteum is a structure that forms in an ovary shortly after the release of oocytes during ovulation.
After ovulation, the corpus luteum continues to develop in response to hormonal stimulation, mainly from LH and FSH.
According to the Endocrine Society, if fertilization does not occur, the corpus luteum breaks down, progesterone levels fall, and menstruation begins.
Corpus luteum and pregnancy
If pregnancy occurs, the developing embryo begins to release a hormone called human chorionic gonadotropin (hCG), which is the substance detected in urine or blood during pregnancy tests.
hCG functions similarly to LH, stimulating the corpus luteum to continue developing. This prevents its breakdown and promotes the release of estrogen and progesterone, which are essential for maintaining the endometrium.
By about the seventh week of pregnancy, the placenta begins producing progesterone and estrogen. It gradually takes over hormone production from the corpus luteum, which then breaks down around the twelfth week of pregnancy.