The average success rates of IVF globally are under 50 percent. This means that almost half the people who undergo IVF do not get pregnant.
What is the most common reason for IVF failure?
Fertility specialists say that arrest of embryos is responsible for IVF failure in over 90 percent of the cases.
Some of the embryos created will die by day 5 in the lab, but even the good ones that survive the initial days and actually look healthy, might die after being transferred to the uterus.
Now there are a number of causes that can result in poor quality, weak embryos, which do not grow beyond a certain stage, but unfortunately these issues are still considered a “black box” in the IVF world and there is no fail-safe way to ascertain what is wrong with the embryos.
Genetic or chromosomal abnormalities can sometimes make the embryo too weak for IVF, while other times the embryo just does not have enough cells to survive and is unlikely to grow.
Why do many IVF embryos fail to develop?
Poor eggs or faulty sperm are responsible for chromosomal abnormalities in embryos.
IVF in women over 40 years of age often results in poor quality embryos, almost 80% of which are chromosomally abnormal. Hence, the low rate of IVF success in older women.
Chromosomal anomalies in the sperm can also lead to chromosomally abnormal embryos but that incidence is reported to be small as compared to its probability in human eggs.
When is IVF most likely to fail?
The main reasons for failure of IVF are:
- Poor egg quality: Embryo implantation rates are higher (at around 50%) in women near the age of 35, as compared to just around 12% in women over 40 years of age. If your uterus is perfectly healthy but the quality of eggs (and the resultant embryo) is not adequate, switching to IVF with donor eggs is more likely to bring you success.
- Poor ovarian response to stimulation: During an IVF cycle, medications are administered to get the ovaries to produce more eggs. If you already have a reduced number of eggs or have elevated FSH levels, your body might not respond properly to IVF medications, which is not a good sign. If your body responds well to the medication and produces more eggs, you have good chances of IVF success as it indicates the normal functioning of hormones in your body but if it doesn’t, then your chances of IVF success may also be reduced.
- Poor sperm factors: The sperm’s role in fertilization of the female egg is complex and they must be healthy, motile, and sufficient in quantity for proper funtion. However, barring chromosomal factors, sperm are usually not the among the reasons for failure of IVF because any quantitative or qualitative problems with the sperm are easily detected during semen analysis and sperm DNA fragmentation testing, and corrective measures can be taken.
The IVF clinic you choose, lab factors, the method of performing the procedure, experience and skills or the doctor, the competence of the embryologist are all factors that can affect your IVF results but over 50 percent of IVF cases will fail even if these conditions are perfect.
Other reasons for failure of IVF
- Uterine problems – Fibroids, polyps, adhesions, or structural abnormalities of the uterus can cause embryo implantation failure
- Hormonal imbalances – PCOD, thyroid problems, or unresolved endometriosis can result in failure of IVF
- Poor endometrial receptivity – Wrong timing of embryo transfer, when the uterine lining is not completely ready can cause IVF failure. This can be improved with ERA testing.
- Immunologic reasons – Aggressive immune reaction of the mother towards the embryo can cause is failure to attach to the uterine lining
- Poor lifestyle – Excessive smoking, alcohol or drug abuse, a sedentary lifestyle or too much exercise can all result in your body rejecting the embryo because it is unprepared to nurture a life.