Why are some cycles unsuccessful?

Becoming pregnant after IVF depends upon success at every step of the process. Therefore steps where the process may not succeed may include:

Unsuccessful stimulation

The following factors can cause a poor response to stimulation:

• sometimes too few eggs develop meaning that there are insufficient eggs to give a good result. This is unfortunately common and is more likely to occur in women over the age of 40;

• sometimes ovarian cysts develop in response to the hormone injections. If these cysts are large, treatment in that cycle is usually discontinued, as it is difficult to monitor the growth of other follicles. The cysts usually disappear by themselves in that cycle

If problems crop up at this stage, we normally recommend that you cancel the cycle (there is no financial cost for doing this) and start again, possibly with a different treatment plan.

Unsuccessful egg collection

This is uncommon, but can occur when

• ovulation has occurred earlier than expected;

• the follicles just do not contain a retrievable egg;

• hCG was not given approximately 36 hours before the attempted egg collection;

Unsuccessful fertilisation

This is usually due to a recognised problem with the sperm. However, occasionally it may occur when the sperm appears to be normal and sometimes may be the explanation for the couple's failure to conceive naturally. Fragmented or immature oocytes usually do not become fertilised. ICSI may be recommended for future treatment cycles to improve the chance of fertilisation.

Embryo transfer but no pregnancy

Unfortunately, this is still the most common outcome for an IVF cycle. Usually, we will be unable to tell you why a pregnancy has not occurred after an apparently straighforward transfer of seemingly healthy embryos. This the area in which all scientists are hoping to find the answers. It is currently thought that the major factor in the failure of the embryo to implant is the quality of embryo itself. Even though an embryo may look ideal, there are still likely to be critical defects which limit its ability to implant successfully.

Non-continuing pregnancy

About 75% of those who become pregnant eventually give birth to a normal baby, however sadly early pregnancy losses are common than in non-IVF pregnancies. The following things may occur:

• biochemical pregnancy - a pregnancy lost in the first few days, where the only sign that the pregnancy has occurred is the biochemical detection of hormone in blood;

• ectopic (tubal) pregnancy - this is usually picked up on early ultrasound. Surgery is usually needed to remove the pregnancy in this situation;

• miscarriage - this is where the pregnancy is lost in the early weeks of pregnancy. Sometimes the fetus itself has not even formed and only a small sac of fluid is seen on scan (delayed miscarriage). Sometimes the fetus may be lost even though it is appears to be healthy on an earlier ultrasound scan.
  The risk of miscarriage increases significantly with maternal age. It is generally accepted that patients under 30 have a 5 - 10% chance of miscarrying. This rises to approximately 15% in the 30 - 34yrs age group and is approximately 10 -20% for patients aged 35 - 39. For patients 40 years and older, the risk of miscarriage is approximately 20 - 40%.

If your treatment cycle is unsuccessful in achieving a pregnancy, it is suggested that you wait more than one full cycle before starting again. This is to allow you to wind down and get back to some 'normal' living again.

Effect of Maternal age on Fetal Abnormalities