Menstrual cycle & ovulation
The LH surge usually happens around 24 to 36 hours before ovulation. Ovulation predictor kits detect it in urine. In IVF, clinics prevent a natural surge and use a trigger injection instead.
Also known as: luteinising hormone surge
Sources
Last reviewed: 23 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.