Until recently, little research has been done on the outcome of adverse pregnancy related complications due to the use of frozen oocytes in conception. Vitrification is a relatively new technique that allows eggs to be frozen quickly, instead of the slow freezing process of cryopreservation, which can cause problems with ice crystals forming, ruining the quality of the egg. In October of 2012, the American Society for Reproductive Medicine lifted the ban on vitrification, determining it to be a safe and effective process.
A study published in Fertility and Sterility on July 23rd, has now shown that there is no significant difference in perinatal and obstetric outcomes from pregnancies conceived from frozen eggs versus those from fresh. This suggests that egg freezing using vitrification is safe to utilize and causes no additional harm to the fetus before, during, or after birth.
Researchers from a university-affiliated IVF center, collected data on over 2,000 pregnancies spanning from 2007 to 2012. By comparing those achieved with vitrification (804 pregnancies and 1,027 newborns) versus those from fresh cycles (996 pregnancies and 1,224 newborns), doctors discovered that while pregnancies from vitrified eggs were more likely to undergo invasive procedures (ie. amniocentesis), there was no significant difference in adverse outcomes between the two groups.
Women who used vitrified eggs were more likely to be of advanced maternal age, while those in the fresh oocyte group had a higher incidence of previous preterm labor. Both groups were assessed for their current pregnancy related effects, such as incidence of caesarian section, low-birth weight, birth defects, etc. and there was no clinical difference between the two.
Oocyte preservation has become more widely used for women who wish to delay childbearing, whether for social reasons or to have more time in-between pregnancies. While still a new process, egg freezing has proven itself to be a safe and effective process to preserve fertility.