LH Surge
A rapid rise in luteinizing hormone that triggers ovulation roughly 24 to 36 hours later.
Detected by urine-based ovulation predictor kits and incorporated into the Marquette Method.
Luteinizing hormone is produced by the pituitary gland. The surge can be detected at home using ovulation predictor kits (OPKs) or a fertility monitor used in the Marquette Method.
A positive LH test is a strong signal that ovulation is likely soon, but it does not by itself confirm that ovulation occurred or describe the entire fertile window.