Freezing of Embryos
Embryo Freezing (or Embryo Banking) is the most well established method of fertility preservation with the largest amount of outcome data published in the literature. Successfully used for decades, embryo freezing has been responsible for births of hundreds of thousands of babies worldwide.
Embryo freezing requires a woman to undergo ovarian stimulation. In a natural menstrual cycle, only one mature egg is usually released from the ovary for possible fertilization. In embryo freezing, the patient takes daily hormonal injections that encourage the ovaries to develop multiple mature eggs. When these eggs are ready, they are retrieved with a thin needle inserted into the ovary under ultrasound control via the vagina. The patient is usually asleep for this procedure under intravenous sedation given by an anaesthesiologist, which takes only a few minutes.
Retrieved eggs are mixed with partner’s (or donor’s) sperm for fertilization, and embryos are created. The embryos are cultured for a few days, and then frozen for future use.
Who May Benefit from Embryo Freezing
Embryo freezing is a routine procedure for both medical and social fertility preservation (unlike egg freezing, which is considered experimental if performed for social reasons). Because embryo freezing requires sperm, embryo freezing may not be a good option for women who do not have a committed partner. Many single women, for this reason, choose egg freezing instead. Embryo freezing, however, is still the best and most established method of social fertility preservation for couples in stable relationships.
Embryo freezing takes a few weeks to complete. Some newly diagnosed cancer patients may not have enough time before they are scheduled to undergo chemotherapy or radiation to freeze embryos (or eggs). Even when patients have enough time for an embryo freezing cycle, a single embryo freezing cycle may not suffice to freeze enough embryos.
The literature suggests that cancer patients typically produce only approximately eight embryos per cycle, which may not be enough to offer a high probability of future pregnancy. Other fertility preservation methods such as ovarian tissue cryopreservation may be a better option, depending on the treatment time frame.
How Many Embryos to Freeze
With a decades-long history, embryo freezing has considerable outcome data to determine how many embryos should be frozen in order to have a reasonable chance of future pregnancy. How many embryos a patient should freeze will depend on her age and ovarian reserve status. For younger women with normal ovarian reserve, IVF Specialists typically recommends freezing of at least 20 embryos. As embryos frozen later in life have a lower potential of leading to a pregnancy, women in their 30s and 40s should consider freezing significantly more.
Embryo Freezing Compares Favourably with Fresh Embryo Transfer
In a study published online on May 10, 2016, in Molecular Human Reproduction, authors report that neonatal outcome data of over 2000 births indicates that embryos that underwent vitrification (flash freezing) with subsequent warming and embryo transfer were equal, if not slightly better than fresh embryo transfers. Overall, better or comparable perinatal outcomes (in terms of higher birthweight and lower risk for small-for-gestational age, prematurity rate, perinatal death, or for low birthweight) have been reported for singletons born after vitrified embryo transfer compared with fresh embryo transfer. According to the single available study with sufficient sample size, the congenital malformation rate was found to be comparable after vitrified and fresh embryo transfers.
This is good news indeed, as ART laboratories across the world over have switched to vitrification of embryos rather than the previous method of cryopreservation referred to as controlled rate freezing. Further, evidence is mounting that deferred embryo transfer, or performing the transfer on a menstrual cycle subsequent to the one used to create and vitrify blastocyst stage embryos, have greater implantation rates than fresh transfers.
We at Indo Nippon IVF take great pride in our Embryo Freezing Program. Our Scientific Director Goral Gandhi is a pioneer in the field of Vitrification. We use the latest and the best Japanese technology called Cryotech Vitrification to preserve your precious embryos. We have almost 100% embryo survival rate. Our aim is to preserve your embryos with utmost care and cutting edge technology till we are able to complete your family with those frozen embryos!