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Immature IVF Eggs

Immature IVF Eggs on the Day of Egg Retrieval, What Does it Mean?

What are immature IVF eggs?

Immature eggs at the IVF egg retrieval have not yet reached “meiotic competence”. Meiotic competence is achieved when eggs undergo the first meiotic reduction to the metaphase II stage (“M2”) of meiosis.

  • Meiosis is a type of cell division that is involved in production of both sperm and eggs
  • The end result of meiosis is halving the number of chromosomes and genetic material
  • Then, when sperm and egg combine, the resulting embryo has the proper chromosome number and full component of genetic material

Do immature eggs fertilize with IVF?

No. Immature eggs are not capable of fertilizing. However, sometimes it is possible to have eggs mature in the lab (in vitro maturation) and then fertilize them.

How common is it to have immature eggs?

  • Some immature eggs are commonly obtained at IVF
  • Usually, about 10-15% of the eggs recovered at the egg retrieval are immature
  • Sometimes we see an increased percentage of immature eggs. In rare cases, most (or even all) of the eggs are immature
  • The percentage of immature eggs is expected to be higher when the majority of the ovarian follicles are small at the time of the HCG trigger shot

In some cases, a woman will have a predisposition to giving a high percentage of immature eggs with IVF. In such cases, the IVF ovarian stimulation protocol should be modified to try to recover more mature eggs with any future IVF cycles.

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