Luteal Phase Defect

The luteal phase of the menstrual cycle begins at ovulation and ends the day before menstruation begins for your next cycle. The purpose of this phase is to prepare your body to sustain a pregnancy. During the luteal phase, the follicle cells that surrounded the egg before ovulation transform into the corpus luteum, a glandular structure that secretes large amounts of progesterone. The large amount of progesterone that is secreted by the corpus luteum works to thicken the uterine lining, which prepares the uterus for successful implantation of an embryo in the event that the egg is fertilized. The luteal phase typically lasts at least 10 days.

If the luteal phase lasts fewer than 10 days (meaning that menses begins less than 10 days following ovulation), the uterine lining will not be adequately prepared for successful implantation, and various problems can ensue, including miscarriage. While there are several causes of luteal phase defects, the result is progesterone deficiency during the luteal phase. Fortunately, once you have identified that you have a luteal phase defect, it is often easily treatable under the care of a physician.
The OvaCue can help you track your progesterone levels following ovulation. If you suspect that you might have a luteal phase defect, keep taking vaginal readings even after the OvaCue has confirmed ovulation. Remember, under “normal” circumstances, vaginal readings will remain elevated throughout the luteal phase, indicating high progesterone levels. If progesterone levels dip during the luteal phase, this will be reflected in a downward trend in your vaginal readings.
The graph below provides one example of how the OvaCue readings might look with a luteal phase defect. Notice that the oral and vaginal readings during the follicular phase (first half of the menstrual cycle) follow the expected trends. A Cue Peak is seen at Cycle Day 5, and the vaginal readings trend downward following the Cue Peak. The Vaginal Rise occurs at Cycle Day 13, indicating the shift from estrogen to progesterone dominance and suggesting that ovulation occurred successfully. Then, notice that following the Vaginal Rise, the vaginal readings immediately begin to fall and remain low for the rest of the cycle. This downward trend in the vaginal readings suggests that progesterone levels are falling.