When IVF fails: factors associated with treatment failure

This study examined the factors associated with the chances of in vitro fertilization failure.

In vitro fertilization, or IVF, is a fertility treatment in which an egg is fertilized by sperm outside of the body. While IVF is often recommended as a treatment for couples struggling with infertility, only 32% of attempts actually result in a live birth.

Previous research has identified a number of factors that can affect the success of IVF, such as the age of the woman, the cause and duration of infertility, and whether or not the woman has had a previous pregnancy. However, there are a number of stages through the IVF cycle, including egg retrieval from the ovaries, fertilization, embryo (fertilized egg) transfer into the uterus, and confirmed pregnancy. The success of each stage could be affected by different factors. 

The current study analyzed factors that were associated with the chance of failure in each stage of IVF treatment.

The records of 121,744 women who underwent IVF were examined. Of these, 40% underwent intracytoplasmic sperm injection, a form of IVF in which a single sperm is injected directly into the egg under microscopic vision. The remaining 60% underwent traditional IVF where sperm is added to a dish containing the eggs and they are incubated (maintained at a favorable temperature) together overnight. Factors associated with treatment failure were determined in each of four stages: egg retrieval, fertilization, confirmed pregnancy, and live birth.

75.4% of women did not have a live birth. Age was associated with failure of risk in all stages of IVF.

While 11.8% of 18 – 34 year olds had three or fewer eggs retrieved, 51% of women over the age of 45 had three or fewer eggs retrieved.

Poor fertilization (fertilization of less than 20% of the eggs) occurred in 2.5% of IVF cycles and 0.9% of intracytoplasmic sperm injection cycles. The risk of poor fertilization was 30% higher for those who had no previous pregnancy. For those who had three or fewer eggs retrieved, the risk of poor fertilization was twice as high when undergoing IVF and five times as high when undergoing intracytoplasmic sperm injection compared to women who had greater than three eggs retrieved.

In women who received one or more embryos, 60% of those undergoing IVF and 59.6% of those undergoing intracytoplasmic sperm injection failed to achieve a positive pregnancy test. Failure to achieve a positive pregnancy test was associated with age; compared to 18-34 year olds, those greater than 45 years of age had 55% higher risk of a negative pregnancy test with IVF and 49% higher risk with intracytoplasmic sperm injection.

27.8% of those with a positive pregnancy test failed to achieve a live birth. For both types of treatment, increased age was associated with lower rates of live birth.  Compared to 18-34 year olds, those greater than 45 years of age were 2.5 times less likely to achieve a live birth.

Female age is a key predictor of failure to have a live birth following IVF as well as the risk of poor performance at each stage of treatment.

This was a retrospective study, which have lower statistical power than controlled comparison studies.