Luteal phase

Overview

The luteal phase is a stage in the menstrual cycle of humans and other mammals. It occurs after ovulation and before the start of menstruation. The luteal phase is characterized by the presence of the corpus luteum, which secretes progesterone and some estrogen. These hormones are crucial for maintaining the endometrium and preparing it for a potential pregnancy.

Diagram of the menstrual cycle, including the luteal phase.

Physiology

The luteal phase begins immediately after ovulation, which is the release of an ovum from the ovary. Following ovulation, the ruptured follicle transforms into the corpus luteum. The corpus luteum is responsible for the production of progesterone, which is essential for the maintenance of the uterine lining.

Hormonal Changes

During the luteal phase, progesterone levels rise, leading to the thickening of the endometrial lining. This prepares the uterus for the possible implantation of a fertilized egg. If fertilization does not occur, the corpus luteum degenerates, leading to a decrease in progesterone and estrogen levels, which triggers the shedding of the endometrial lining, known as menstruation.

Duration

The luteal phase typically lasts about 14 days, but it can range from 11 to 17 days. The length of the luteal phase is relatively constant for each individual, although it can vary between different individuals.

Clinical Significance

A short luteal phase, known as luteal phase defect, can be a cause of infertility or recurrent miscarriage. This condition is characterized by insufficient progesterone production, which can prevent the proper implantation of an embryo.

Related Pages

• Menstrual cycle
• Ovulation
• Corpus luteum
• Progesterone
• Endometrium