In-Vitro Maturation (IVM) is the process of allowing the immature eggs that were retrieved to undergo oocyte maturation in the laboratory. It involves incubation time with or without additional maturation hormones added to the culture solution.

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Eggs that are retrieved from the follicles of women undergoing IVF procedure can be categorized into 3 different stages of maturation - gv, m1, and m2. The most immature stage is gv, germinal vesicle stage, which could take up to 48 hours to mature. The intermediate stage of egg maturation is m1, metaphase I, which may require between 2 to 24 hours of incubation before they mature. Mature eggs are those that are at m2, metaphase II, and this is the stage of maturation that eggs will have to be at for them to fertilize.

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IVM can rescue a cycle with only immature eggs (some IVF clinics will only work with mature eggs and will discard immature ones). IVM can also increase the number of embryos that patients can pick from for embryo transfer especially those that produce very few eggs where some of those eggs are immature.