Post-Peak Phase

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 7, 2026

The phase of the menstrual cycle from the day after Peak Day through the last day before the next menstrual bleed, corresponding to the postovulatory or luteal period. Hilgers established that the post-Peak phase is the stable half of the cycle, typically lasting 11 to 16 days in healthy ovulatory cycles.⁷⁹ This stability is what makes it clinically reliable. A post-Peak phase of 8 days or fewer meets the Hilgers criterion for Type I luteal phase deficiency, indicating inadequate progesterone support for implantation and early pregnancy maintenance. Shortened post-Peak length is identified directly from the cycle chart, before any hormone panel is drawn. RRM clinicians use post-Peak length as a screening signal. It is one of the earliest detectable indicators of a correctable hormonal deficit.

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.