Ovulation is the release of a mature egg from the ovary. It signals the beginning of your fertile period.
LH (Luteinizing Hormone) is one of the hormones produced by the pituitary gland. It is secreted at very low levels throughout your menstrual cycle. Once a developing egg follicle reaches a certain size, LH secretion surges to high levels. This hormone surge is what triggers ovulation about 24 to 48 hours later. Your LH surge is important because it initiates the beginning of ovulation.