GnRH controls the release of two other hormones from the pituitary gland. LH stimulates the production of progesterone in the second half of the cycle.
Progesterone strengthens the endometrium and helps nourish fertilized ova.
In other words, estrogen and progesterone are vital to a woman s fertility and menstrual cycle. Dysfunctional uterine bleeding is a possibility when a hormonal imbalance occurs for various reasons. Normally, an LH surge triggers ovulation and progesterone production increases in the ovary. The progesterone level then rises until about a week before the end of the menstrual cycle, at which point it drops. The drop helps cue the body that it is time to shed the uterine lining.