In Vitro Maturation of Oocytes

G. Durga Rao, M.B.B.S., M.R.C.O.G.; Seang Lin Tan, M.B.B.S., F.R.C.O.G., F.R.C.S.(C.), M. Med. (O&G.), M.B.A.


Semin Reprod Med. 2005;23(3):242-247. 

In This Article

Abstract and Introduction


In vitro maturation of oocytes is a safe and effective treatment offered in some fertility centers for assisted reproduction, where immature oocytes are retrieved from unstimulated ovaries. Therefore, the procedure avoids ovarian stimulation with expensive gonadotropins, side effects of the medications, and risks such as ovarian hyperstimulation syndrome. Added advantages are reduced frequency of monitoring scans and shorter treatment regimen compared with in vitro fertilization. The candidates initially considered were women with polycystic ovaries having multiple antral follicles, but the indications are widening to include women with primarily poor quality embryos in repeated cycles and poor responders to stimulation. The two new applications for in vitro maturation we are now successfully implementing at McGill Reproductive Center are for oocyte donors and for fertility preservation, especially in women with cancer who are undergoing gonadotoxic therapy. In young women without partners needing this treatment for fertility preservation, it is combined with vitrification of the oocytes. We have achieved a 38% clinical pregnancy rate per cycle in women having IVM for infertility treatment up to the age of 35 years, and 50% clinical pregnancy rate per cycle in recipients of IVM egg donation.


In vitro fertilization (IVF), since the birth of Louise Brown in 1978,[1] has advanced tremendously and has proven to be a very successful treatment for infertile couples.[2,3] However, there are some drawbacks to this mode of treatment: the high costs involved, the inconvenience of daily gonadotropin injections, side effects of medications, and the requirement for multiple monitoring visits; the most important risk is ovarian hyperstimulation syndrome (OHSS). OHSS, with an incidence of up to 6% in high-risk patients undergoing IVF treatments, can be fatal,[4] and is more likely to develop in young women with polycystic ovaries (PCO).[5] There is also the worrying (but unproven) link between repeated courses of gonadotropin injections and ovarian cancer,[6] which deters many women.

The success of IVF is due to the creation of multiple embryos available for transfer, so the logical solution to counteract the disadvantages of IVF is to retrieve immature oocytes from the unstimulated ovary, enable maturation of immature oocytes in vitro, and fertilize the resulting mature oocytes to create multiple embryos. The research into maturation of immature oocytes was reported as early as 1935[7] by Pincus and was continued by Edwards in 1965 and 1969.[8,9] However, it took 13 years after the first IVF child was conceived for the first human pregnancy from an in vitro matured oocyte to be reported in 1991.[10] Research continued thereafter and progress made by Trounson et al[11] helped incorporate in vitro maturation of oocytes (IVM) as a form of treatment to be offered to eligible infertile patients. Many groups have demonstrated that IVM is a successful treatment for women with PCO and PCOS (polycystic ovarian syndrome), but our endeavor is to extend this safe treatment modality to include women with various other fertility problems. This article discusses oocyte maturation and the factors controlling it, the clinical protocol used by our center, and the application of this treatment in different patient groups.


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