During which phase of the menstrual cycle does the LH surge occur, along with elevated estrogen levels?

The LH surge occurs during the ovulation phase of the menstrual cycle, which is characterized by a dramatic increase in luteinizing hormone (LH) and is closely preceded by elevated estrogen levels. This surge triggers ovulation, causing the mature follicle to release an egg into the fallopian tube. The rise in estrogen, primarily produced by the developing follicles, is crucial as it stimulates the anterior pituitary to release the LH surge. The timing of this event is critical for reproductive processes, as it marks the peak of fertility in the cycle.

In contrast, the follicular phase involves the gradual buildup of follicles and low levels of LH and estrogen before the surge occurs. The proliferative phase is associated with the rebuilding of the uterine lining and also does not coincide with the LH surge. The secretory phase follows ovulation and features lower levels of LH as the focus shifts to preparing the uterus for potential implantation of an embryo.