How Many Embryos Should Be Transferred?

This may be one of the most difficult decisions that patients and their doctors need to make during an IVF or FET procedure.

Most fertility clinics will only replace one or two embryos.  In exceptional circumstances, the specialist doctor may discuss with patients transferring more than two embryos.  The decision on the maximum number of embryos to transfer is made prior to starting the treatment cycle. During the IVF appointment the specialist doctor will make a recommendation for the number of embryos to be transferred, and discuss with patients the risk factors associated with multiple pregnancy (twins and triplets).

Patients then need to nominate the number of embryos that they wish to have transferred, within the number recommended by their doctor.  If the patient’s doctor recommends two embryos be replaced but the patient would prefer one embryo, then one embryo can be put in the consent form and only one embryo transferred.  Conversely, if the doctor recommends one embryo be replaced and the patient would prefer two, then only one embryo can be transferred as this is the maximum considered medically appropriate by the clinician.

Points to consider:

• The incidence of multiple live births when two or more embryos have been replaced is about 9% of all live births in Australia.
• Even with the best antenatal care, the chance of twins dying before, during and after delivery is about ten times that of a singleton pregnancy due mainly to the increased incidence of premature delivery.
• The incidence of cerebral palsy is seven times higher in twins than in a singleton pregnancy, and there is an increased chance of long term disability.
• There can be considerable social and psychological difficulties in raising twins, largely related to having two children of identical age.
• The pregnancy rate for transfer of one embryo is less than for transfer of two embryos in a cycle.
• There is about a seven-fold increased risk of identical twins from transferring one blastocyst (Day 5 embryo) compared to transferring a 4 or 8 cell embryo (Day 2 or Day 3 embryo).

As a woman ages the chance of a live birth pregnancy declines. The chance of a multiple pregnancy also declines with age but only because the chance of pregnancy itself declines. Women over 35 are often encouraged to transfer 2 embryos to improve their overall chance of pregnancy occurring but should be aware that they are at risk of a multiple pregnancy.

Taking into account all of the above statements we recommend considering the following:

If under the age of 35 have a single embryo transfer for the first embryo transfer in an IVF cycle.

If  35 or over discuss the number of embryos recommended for transfer with the doctor before treatment starts, including the option of single embryo transfer.

As always, this decision depends upon your individual circumstances and you are encouraged to discuss all aspects of this decision with your doctor and staff at the fertility centre.