Lutealivaihe

Lutealivaihe refers to the second half of the menstrual cycle in women. It begins after ovulation, when the ruptured follicle in the ovary transforms into the corpus luteum. This glandular structure then produces progesterone and estrogen. The primary role of progesterone during the luteal phase is to prepare the uterine lining, the endometrium, for potential implantation of a fertilized egg. It thickens the endometrium and makes it more receptive to pregnancy.

If fertilization and implantation occur, the corpus luteum continues to produce progesterone, supported by the hormone hCG produced by the developing embryo. If pregnancy does not occur, the corpus luteum degenerates about 10-14 days after ovulation. This decline in progesterone and estrogen levels triggers the shedding of the uterine lining, resulting in menstruation, which marks the beginning of the next cycle. The luteal phase typically lasts for a consistent duration, usually around 12 to 16 days, which is a key factor in determining a woman's fertile window and overall cycle length. Variations in the length of the luteal phase are uncommon and can sometimes indicate underlying hormonal imbalances or reproductive issues.