Embryo freezing

A well-established method in assisted conception, embryo freezing is now done in an increasing number of clinics worldwide. The first frozen embryo baby was born in 1984.

In this process, the spare embryos are frozen for later transfer. Embryo freezing allows multiple embryo transfers from a single egg collection and improves the chances of live birth.

  • Enables a precautious policy for embryo transfer
  • Lessens the chance of multiple pregnancies
  • Makes the embryos not transferred available for later use
  • Establishes a cumulative pregnancy rate, increasing the overall chances for patients to conceive per IVF cycle
  • Helps patients with complications such as Ovarian Hyper stimulation Syndrome (OHSS)

Embryos are allowed to soak in different solutions of media to dehydrate the cells of water and replace it with cryoprotectant. The cryoprotected embryos are then individually labeled and stored in special plastic straws, which will be put in special cryopreservation chambers. These freezers slowly (at -0.3 degrees Celsius per minute) cool the embryos to -35 degrees Celsius using liquid nitrogen. They are then stored in liquid nitrogen at -196 degrees Celsius. At that extremely cold temperature, cellular activity essentially stops, allowing the embryos to remain viable indefinitely.

The recent trend has moved away from traditional "slow freezing" technology used since the 1980's. The newer vitrification method for IVF embryo freezing is becoming a more widely used technology today.


Vitrification is the process of converting something into a glass-like solid that is free of any crystal formation.

Vitrification in IVF can allow freezing of spare embryos with better post-thaw survival rates and higher pregnancy and live birth rates from frozen embryo transfer cycles.

Embryos are frozen at very high cooling rates using highly concentrated cryo-protectants resulting in the glass like amorphous state.

Many studies have shown that vitrified embryos have a higher survival rate than slow freeze embryos. At Crea, we are happy to offer this cutting edge technology to patients who choose to cryo-preserve their embryos.