Having a one baby at a time is desirable for many reasons, particularly when considering the health of the mother and child, as it is well known that twins and multiples are often delivered prematurely and mothers have a higher risk of preeclampsia and other pregnancy complications. Early use of IVF was associated with a high twin live birth rate, thus the rise of Single Embryo Transfer (SET) was born out of the desire to decrease the occurrence of twins or multiples, for the sake of the mother and child’s health.
The primary reason that SET has not been the standard practice with IVF is because doctors were not able to definitively determine which embryo was the very best to transfer. Hence, multiple embryos would be transferred at once in order to increase the likelihood of pregnancy. Patients were satisfied because with a single IVF cycle they were likely to get pregnant, as one of their embryos surely would be normal and implant. Unfortunately, for some patients, many normal embryos or many abnormal embryos could be transferred at once. Physicians just didn’t know. The result for many women was a failed IVF cycle or multiple gestations, and at times, this was more than twins!
SET, along with the genetic testing of embryos, has revolutionized IVF because doctors are able to choose the embryo that is most likely to result in a live birth. After a woman undergoes ovarian stimulation, a number of eggs are retrieved, which can vary depending on a woman’s age and medical history. These eggs are then fertilized with the partner’s sperm. Some eggs will fertilize and become embryos and others will not. Although embryos with as few as 8 cells can be tested, the ideal embryo is one that reaches the blastocyst stage of development. These cells will be tested using either PCR-based, microarray, or next generation sequencing technology to see if they are chromosomally normal. This is called preimplantation genetic screening (PGS). For couples with single gene disorders, preimplantation genetic diagnosis (PGD) can also be performed to minimize the transmission of a genetic abnormality. At this stage it is possible that a couple will have many normal and healthy looking embryos, or they could have none. It is a “numbers game” based on how many eggs are retrieved, number of embryos created, and whether those embryos are chromosomally normal.
The statistics show us that the live birth rate hovers around 60% for women using IVF regardless of age, as long as the embryo is chromosomally normal. Women with multiple miscarriages or problems getting pregnant due to their age, with the help of IVF, are highly likely to get pregnant as long as at least one of their embryos is normal. Additionally SET has minimized the monetary and emotional burden of having multiples. The psychological impact of multiples on a couple’s relationship compared to singletons has not been well studied. However, a previous study by the Twin and Multiples Birth Association (TAMBA) has shown higher rates of divorce compared to their singleton counterparts. The rate of postpartum depression also appears to be higher for mothers of multiples. The use of SET combined with preimplantation genetic screening has decreased this potential burden for couples seeking children while maximizing their chances of a healthy live birth.
For more information on SET and other Fertility issues, please contact IRMS by visiting our Contact Us page or giving us a call at (973) 322–8286.