Does Regular Menstruation Assure Regular Ovulation?

During the course of evaluation and treatment for infertility, women often inquire as to whether they are ovulating with certainty.  It is generally perceived that regular predictable menstruation indicates regular ovulation.   It is a well-established fact that in spite of regular menstrual cycles, a significant percentage of these cycles are anovulatory.  The incidence of anovulation in regularly menstruating women is reported to be between four and ten percent depending on the methods used to detect ovulation.  The paper from NIH reviewed here suggests that using home LH monitoring kits that are readily available to the public, will lead to an overestimate of anovulation.  In their study, those patients monitoring with the LH test kit detected anovulation in 13.2% of cycles, whereas if luteal phase progesterone was used to predict anovulation, the incidence was 8.4%.

It is important to recognize that all of the women studied had regular periods occurring every 21-35 days, and were healthy with no infertility, gynecologic disorders, or chronic diseases.  It is logical to suspect that among a population of women with more cycle irregularity, infertility, or chronic diseases, the percentage of anovulatory cycles would be higher.

In the clinical setting, it is common for physicians caring for infertile couples to use serial ultrasonography to document ovulation.  Since ultrasonography is considered the gold standard for detecting failure to ovulate, this approach leads to fewer instances of failure to detect anovulation.

Patients must be aware that using readily available home LH testing kits is a less than perfect method of detecting ovulation leading to a suspicion of anovulation in a greater number of cycles than actually occurs.  Additionally, clinicians should track menstrual cycles carefully among infertile women (even those who are menstruating regularly) to accurately diagnose anovulation.