Midluteal

Midluteal refers to the middle portion of the luteal phase of the menstrual cycle, typically about seven days after ovulation, roughly day 21 in a standard 28-day cycle. Timing can vary among individuals.

During the midluteal phase, the corpus luteum secretes progesterone (and estrogen) at higher levels. Progesterone drives the secretory transformation of the endometrium, supporting glandular development, secretions, and increased vascularization to prepare the lining for potential implantation. Basal body temperature often remains elevated during this period due to progesterone.

If fertilization and implantation occur, human chorionic gonadotropin (hCG) from the developing embryo rescues the corpus luteum, sustaining progesterone production until the placenta assumes this role in early pregnancy.

If pregnancy does not occur, the corpus luteum degenerates after about 12–14 days, progesterone declines, and the endometrium sheds in menses, ending the luteal phase and returning to the follicular phase of the next cycle.

Clinically, midluteal progesterone testing—typically performed about seven days after ovulation (around day 21 in a 28-day cycle)—is used to confirm ovulation and assess corpus luteum function in fertility evaluations. Low midluteal progesterone may be discussed in the context of luteal phase insufficiency, though this diagnosis and its management are individualized and somewhat debated.

Overall, the midluteal phase is a key window for endometrial preparation and early pregnancy support, with variability in timing and hormone levels among individuals.