Egg Freezing
A woman’s fertility depends largely on the number and quality of her eggs. The ovarian reserve is finite: it peaks before birth at approximately 6–7 million eggs and declines throughout life.
Egg cryopreservation allows a woman to freeze eggs at a younger age. These eggs may offer a better chance of pregnancy in the future than eggs collected later, when both quantity and quality may have declined.
Vitrification—a rapid cryopreservation technique that minimises ice-crystal formation and limits damage during freezing and warming—has made egg freezing a practical option for preserving future fertility.
A growing body of international evidence indicates that vitrified eggs can achieve outcomes comparable with fresh eggs, and available data do not show an increased risk of preterm birth or congenital abnormalities.
More than one stimulation cycle may be needed to store enough eggs. The number required for a reasonable chance of one live birth varies with age; on average, approximately 15 eggs may be needed under age 35, around 20 between 35 and 40, and more after 40.
Egg freezing is generally more effective at a younger age. The appropriate target number of stored eggs should be discussed individually with a fertility specialist.
Ioannis A. Sklavounos MD MSc DFFP
Consultant Obstetrician and Gynaecologist
Specialist Training and Fellowship in the United Kingdom
T.Senior Clinical Fellow – Liverpool Woman’s Hospital UK
IVF
