The luteal phase of a woman's menstrual cycle is the number of days in between ovulation and the onset of the next cycle. An average luteal phase length is approximately 14 days and normally will not vary by more than one day in any woman. If the length does vary, the woman is likely to be diagnosed with a luteal phase defect and will have trouble with proper progesterone production, which can lead to problems with implantation of the fertilized egg and result in recurrent miscarriage.
The luteal phase is named after the corpus luteum, which is a structure that grows on the surface of the ovary where the mature egg is released during ovulation. The corpus luteum is responsible for making progesterone which prepares the uterine lining for pregnancy, the phase must be at least 10 days long in order to support a pregnancy, if not miscarriage is going to be the most likely outcome. The length of a woman's luteal phase determines the time of ovulation within the menstrual period. Ovulation can be delayed or absent for a number of different reasons which can include, illness, stress, increased activity, certain medications or something else. The only way a woman can accurately predict the length of her luteal phase is through a hormone specific blood test, otherwise charting and tracking basal body temperature can help give her some type of idea.
Some women will experience an extremely irregular cycle and may need help in determining exact luteal phase length. For couples having trouble conceiving, determining the actual ovulation date will help increase the chances of pregnancy so it is important to keep track of signs of ovulation and follow the advice of a medical professional if any recommendations are given. The length of the luteal phase has a great deal to do with fertility and if it is too short, the body will not make enough hormones to support a fertilized egg and a woman could miscarry. Too much progesterone could lead to a false-positive pregnancy test, which can be disappointing and frustrating. With the right treatment however, a luteal phase defect is easily treated and a woman should be able to go on to conceive and have a baby at some point in the future.