What is in vitro fertilization (IVF)?

Many women and their partners try for a long time to get pregnant, but can’t. Some may turn to the process of in vitro fertilization (IVF) to help them have a baby.

With IVF, a woman’s egg cells and a man’s sperm cells are put together in a dish in a special fluid in the laboratory. The new cell that is made when an egg cell and a sperm cell combine is called an embryo. The doctor then transfers the embryo into the woman’s uterus (womb). The embryo implants (attaches) to the wall of the uterus, where it develops and grows into a baby.

As part of the IVF process, the woman is given special drugs that cause her ovaries to release more egg cells than normal. The man also gives a high number of sperm cells. With many egg and sperm cells to work with, several embryos are often made. The doctor will transfer one to four embryos, based mainly on the woman’s age, into her uterus to lower the chances that she will have more than one baby. That means there may be some embryos left over.

What is embryo cryopreservation?

Embryo cryopreservation is the process of freezing and storing the extra embryos. The embryos are then thawed and used at a later time. Embryo cryopreservation is a vital part of most IVF programs. According to the National Embryo Donation Academy, there were approximately 500,000 embryos in storage in the United States in 2011.

Why is embryo cryopreservation done?

There are many reasons a man and woman might choose to freeze and store their embryos:

  • They may feel it is a better option than having the extra embryos destroyed.
  • It can provide another chance to get pregnant if the IVF process fails the first time. The couple will not have to go through IVF again.
  • If the man and woman have a baby, they can use the embryos later to have a second baby.
  • The woman can save embryos before she begins treatments, such as for cancer, that might reduce or eliminate her chances of getting pregnant.
  • The embryos could be saved and given to someone else in a donor program.
  • The embryos could be saved and donated for research.

Last reviewed by a Cleveland Clinic medical professional on 05/12/2014.


  • Michelmann HW, Nayuda P. Cryopreservation of human embryos; Cell and Tissue Banking June 2006, Volume 7, Issue 2, 135-141.
  • AbdelHafez FF, Desai N, Abou-Setta AM, et al. Slow freezing, vitrification and ultra-rapid freezing of human embryos: a systemic review and meta-analysis; Reproductive Biomedicine Online; 2010; 20, 209-222.
  • Wolf, D. Gamete and embryo cryopreservation Glob. libr. women's med., (ISSN: 1756-2228) 2008; DOI 10.3843/GLOWM.10366
  • National Embryo Donation Academy. Reference Manual Accessed 5/13/2014.
  • American Society for Reproductive Medicine. Quick Facts About Infertility Accessed 5/13/2014.

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