In a textbook 28-day cycle, ovulation occurs on day 14, and the luteal phase is from day 15 to day 28. A women’s cycle can vary from 21 to 35 days. The last two weeks of the cycle are the luteal phase.
During the luteal phase, hormone levels change, and the uterine lining prepares for the implantation of a fertilized egg. This typically occurs six to 12 days post ovulation. A shortened luteal phase can make it difficult to become pregnant. This is known as a luteal phase defect.
This article discusses the luteal phase of the menstrual cycle. It explains what happens during the luteal phase and related problems.
What Happens During the Luteal Phase
Ovulation is a process that begins when the level of luteinizing hormone or LH surges and ends 16 to 32 hours later with the release of an egg from the ovary.
During ovulation, the ovaries release a single egg from only one of the two ovaries each menstrual cycle. Luteinizing hormone triggers enzymes to break down the wall of the follicle to release the egg. Then it stimulates the follicle to form the corpus luteum and produce progesterone.
During the luteal phase, estrogen and progesterone increase and work together to create changes in the lining of the uterus that prepare it to accept an embryo, should conception occur. The lining thickens so that it will be in the right condition for implantation and nourishment of a fertilized egg.
Fertilization happens in the fallopian tubes, and the timing of the thickening of the uterine walls must coincide with the arrival of the fertilized egg, which can take a few days after ovulation.
If implantation does not occur, estrogen and progesterone levels decline, and the lining of the uterus, called the endometrial lining, begins to be shed. This then leads to menstruation. The luteal phase ends when menstruation begins. That marks Day 1 of your next menstrual cycle.
Luteal Phase Defect
A luteal phase defect (also called a luteal phase dysfunction or luteal phase deficiency) refers to a problem with the luteal phase. The result is that the uterine lining might not be optimally prepared for the implantation of a fertilized egg.
However, the luteal phase defect is only a theoretical cause of infertility or miscarriage. The idea underlying this theory is that if the uterus is not fully prepared to support a pregnancy, a woman will not get pregnant at all, or the pregnancy will not implant properly and ultimately miscarry.
What Is the Follicular Phase?
There are just two menstrual cycle phases that occur during every monthly cycle. The first phase is the follicular phase or the proliferative phase. The follicular phase begins on Day 1 of the menstrual cycle when estrogen and progesterone levels are at their lowest.
During this phase, the uterine lining, or endometrial lining, is shed through menstruation and then begins a period of regrowth and thickening in preparation for an embryo should conception occur. This follicular phase lasts about 10 to 14 days, or until ovulation occurs, after which you pass into the luteal phase.
A Word From Verywell
Your menstrual cycle is guided by a complex interplay of hormones that nature developed to support the pregnancy. Get to know what is happening at each phase so you can understand the normal functioning of your body.
Research links moderate drinking during the luteal phase to decreased odds of becoming pregnant.
