By: Dr. Eva Littman, M.D., F.A.C.O.G.
Practice Director
Some may argue that the endometrium cannot be adequately prepared for implantation during a fresh gonadotropin stimulated cycle, due to the excess estrogen and progesterone levels seen by the endometrium during stimulation. I beg to differ with this hypothesis. Across the nation, fresh IVF cycles are done routinely. Statistics nationwide show that Fresh IVF pregnancy rates are significantly better than frozen IVF rates, by a margin of >20%. Most IVF centers nationwide prefer to do fresh embryo transfers rather than frozen for this very reason. Also, if stimulated endometrium was not hospitable for implantation then neither clomid/IUI cycles, or FSH/IUI cycles, would be successful!
The only defendable condition in which frozen may be better than fresh is in patients who have PCOS. PCOS is diagnosed by having two out of the three following characteristics: PCOS
appearing ovaries on ultrasound, Irregular menses defined as menstrual cycles >35 days apart, or hyperandrogenism. In cases of PCOS, women have an average antral follicle count
of 15-25 eggs on each ovary. This is greatly increased from the average antral follicle count of 6-10 eggs in a normal ovary. Therefore, when these women undergo controlled ovarian
hyperstimulation, their estrogen and progesterone levels can be 2-3 times higher than a patient with normal ovaries. The exposure to these high levels of hormone, “SOMETIMES,” causes the endometrium to be out of sync with the embryo development. PCOS also is a higher risk factor for the development of OHSS or Ovarian Hyperstimulation Syndrome. Therefore, in “SEVERE” cases of PCOS, freezing the embryos and not going through with the transfer is safer for the patient and more likely to result in a pregnancy than a fresh transfer. By no means should this theory apply to patients who do not have this condition. Years of pregnancy data from reputable fertility centers, nationwide show this to be the case. Actually, data shows that the excess manipulation by putting embryos through the freezing/thawing process can make them less likely to develop into a pregnancy. In some centers, over 30% of embryos do not survive the thaw process and another 10% will not progress to the blastocyst stage once thawed.
Women with decreased ovarian reserve or borderline embryo quality will definitely not benefit from this process. At Red Rock Fertility Center, we only freeze the embryos and cancel a fresh cycle if it is indicated by the hormone levels and clinical status of the patient which is the NATIONALLY accepted standard of fertility care.
