Luteinizing hormone is a hormone produced by gonadotropic cells in the anterior pituitary gland. An acute rise of LH ("LH surge") triggers ovulation and development of the corpus luteum. LH plays a key role in reproduction. Mid-cycle, your LH levels increase which triggers your ovaries to release an egg — ovulation. If your LH levels are imbalanced, you might have irregular periods and difficulty getting pregnant. Or high LH levels can be a sign that you’re menopausal.