Failed IVF occurs in approximately 50% of embryo transfers because the embryos were not genetically/chromosomally correct resulting in miscarriage
IVF fails in approximately 50% of embryo transfers. Pregnancy or early miscarriage occurs in most cases because the embryo(s) were not genetically/chromosomally correct. Women are born with a certain number of eggs and never make any more eggs their whole life – eggs accumulate genetic errors as a function of time. Men constantly make new sperm all their lives, therefore, the great majority of sperm even in men 60 and older are genetically normal. There is a slight increase in genetically abnormal sperm after age 55. Other causes of pregnancy failure include compromise of the uterine lining, a traumatic transfer causing contractions and possible expulsion of the embryo or immune factors.
Factors known to adversely affect the uterine lining.
There is strong evidence that blocked tubes filled with fluid, i.e., a hydrosalpinx impair implantation. It is recommended that a hydrosalpinx be removed prior to embryo transfer. Uterine polyps and fibroids are felt to impede implantation and increase the risk of miscarriage. Out-patient hysteroscopy is used to remove polyps and fibroids. Inflammation of the endometrial lining (endometritis), has been found to be a common occurrence in patients with repeated implantation failure. Endometritis can be diagnosed by hysteroscopy and treated with antibiotics. The high estrogen environment seen with a fresh embryo transfer has been shown to cause gland stromal dyssynchrony resulting in lower implantation rates. For that reason, embryos obtained in high estrogen IVF cycles are almost always cryopreserved and replaced in a prepared cryo IVF cycle where estrogen levels mimic those of nature. There are some individuals who are relatively resistant to progesterone and are not getting pregnant because embryo transfer is being performed outside their receptive window. The endometrial receptivity assay (ERA) was designed to test for an individual’s ideal implantation window. If a patient is found to be resistant to progesterone they can be given one or two more days of progesterone therapy, if they are hypersensitive to progesterone they may be given one less day of progesterone prior to transfer. Patients with developmental uterine anomalies, i.e., septate, bicornuate, unicornuate, and didelphic utero have been shown to have lower implantation and higher miscarriage rates.