Whenever a sudden shift is made from fresh embryo transfer to frozen embryo transfer the couple usually have many queries in mind. So, let’s evaluate both and see pros and cons.
Fresh embryos transfer is undergoing ovarian hyper stimulation making of embryos and transferring resultant embryos to uterine cavity in same cycle. In frozen embryo transfer first two steps of controlled ovarian hyper stimulation and process of IVF/ICSI are same but the resultant embryos are frozen using vitrification techniques and not transferred in same cycle. They are thawed and then kept uterine cavity after preparing the uterine cavity.
In patients who are normal or hyper responders the frozen embryo transfers are known to have better results than the fresh embryo transfer . The reason can be that due to ovarian hyper stimulation and high levels of estrogen may have negative impacts on the endometrial receptivity. In some cycles another hormone called progesterone may also be raised, which again decreases embryo implantation rate. Whereas in frozen embryo transfer the body and uterus have already recovered from the impact of hormonal disturbance and hence more receptive.
Because of their reason in patient with PCOS the frozen embryo transfer is associated with higher live birth rate. It also reduces complications like ovarian hypertimulation in these patients.
Another reason where we make a sudden shift from fresh to frozen embryo transfer are when the ovarian stimulation part is good but the endometrial thickness fails to reach an optimal level.
So because of the above reasons we are moving towards more frozen transfer than fresh transfers in self cycle.