Between days 2-4 of your menstrual cycle, Dr. Allen may order preliminary bloodwork to be drawn to check the levels of FSH and E2. The two hormones are often a good indication of ovarian reserve as they are intimately involved in the production of healthy eggs leading to pregnancy. In preparation for ovulation, your body produces FSH to mature the growing egg. As the egg matures, the follicle containing the egg releases E2. At this stage of the menstrual cycle, low hormone levels are desirable.