Timing of the trigger shot during IVF

This needs to coincide with the maximum of the ovarian follicles being more than 15 mm in diameter. It may happen so with numerous follicles having reached 18 to 22 mm as well. The follicles develop an average of two mm in a day with optimum stimulation. Follicles larger than 22 mm will typically harbor overdeveloped eggs, which may possibly fail to fertilize. Follicles less than 15 mm contain underdeveloped eggs which may be more likely to be incompetent following the trigger.