Luteal Phase (LP)

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

The period of the menstrual cycle following ovulation (post-peak) and preceding menstruation or implantation, typically lasting 12 to 16 days. During the luteal phase, the corpus luteum secretes progesterone to prepare the endometrium for potential implantation. A short luteal phase (<10 days) is associated with infertility and impaired endometrial maturation.⁴⁴

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