Nearly half of women with endometriosis who freeze their eggs will later thaw their gametes and half of them will go on to have a successful live birth, a pivotal study suggests.

Spanish researchers examined records for 1044 women with endometriosis who had oocytes vitrified at fertility clinics between 2007-18 and found 46.5% of them came back for their eggs, thawing them a mean of 1.7 years later.

Almost all (98%) of the 485 women who retrieved their vitrified gametes had moderate or severe endometriosis (stage III or IV, according to American Society for Reproductive Medicine criteria).

Overall, 83% of the eggs survived and the cumulative live birth rate (CLBR) was 46%, the researchers reported in Fertility and Sterility.