In Vitro Fertilization: Pregnancy Rates

In Vitro Fertilization (IVF) is one of the Assisted Reproductive Technology (ART) methods used for helping couples to achieve pregnancy. Generally, sub fertile couples or couples who have difficulty with conception undergo this procedure to have a child of their own. However, the success rates of IVF can be quite confusing, as there are lots of misleading reports on pregnancy rates. The pregnancy rate is the number of pregnancies achieved with 100 IVF treatments. Sometimes, the reported pregnancy rate of a particular fertility institute or clinic can give a meaningful hope, but in reality, it may not reflect the actual number.

You must educate yourself regarding how the pregnancy rate is calculated using various parameters, so that you are aware of the actual pregnancy rate.

Population-Based Calculation

Most of the clinics project their success rates, which are calculated on the basis of a specific population. This means that all those patients who are undergoing the IVF procedure are not included in their calculations. Only those patients who are young with a regular menstrual cycle, particularly those who have had limited or no previous treatment, are mainly considered for the calculation of success rates.

Patients in the risk group, i.e those with problems like being over 38 years or having repeated miscarriages and prolonged infertility, are usually excluded from their calculations. As a result, the pregnancy rate appears to be high.

IVF Cancellation Rate

IVF treatments may be cancelled at various stages for different reasons. The treatment can be discontinued before the hCG injection, egg retrieval or embryo transfer stages. The doctor may cancel the treatment because of the following reasons:

  • Poor response to fertility medication
  • Development of only one egg
  • Problems encountered during Pre-implantation Genetic Diagnosis
  • Poor quality of the embryo

When the IVF cancellation rate is higher, it implies that the clinic is strictly selecting the patients undergoing the complete cycle. Such selection will inflate the pregnancy rate, as only patients with high response are selected.

Premature or Live Births

Some clinics include those cases where pregnancy is detected through ultra scan in their success statistics. In fact, this is the ongoing clinical pregnancy rate. However, most of the ongoing pregnancies can lead to miscarriages, premature delivery, multiple birth complications or live births. You need to be aware that such cases are also included to increase the pregnancy rate. In other words, pregnancy rates based on the number of successfully delivered pregnancies are more realistic.

Number of Embryos Transferred

Some clinics transfer one or two embryos, while few clinics transfer more than two embryos to increase the pregnancy rate. However, transferring more number of embryos can result in multiple pregnancies and also complications during delivery, or the babies may die invariably. This practice can also risk the life of the mother. Therefore, in pregnancy rate calculation, the number of such cases are considered to be reliable in comparison to the number of cases with a higher number of embryo transfers.

You can find the success rates of most of the individual clinics at the website of the Centers for Disease Control and Prevention. As many tactics are used by the clinics in projecting a high pregnancy rate, couples planning to conceive a child should make a well-thought decision after considering several factors, such as the track record of the infertility center, their integrity, experience, intelligence, compassion and reputation. It is important to understand the parameters used for the calculation of pregnancy rates, to know the actual number. 

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