Single Embryo Transfer (SET)

There are improved techniques for growing and selecting the best quality embryos so that only one embryo is transferred, rather than two or more, to minimize the risk of multiple births for women undergoing in vitro fertilization (IVF) without compromising the chance of a successful pregnancy.

CCRM’s ultimate goal is to help our patients achieve successful singleton pregnancies. Although, twins or “multiples” might seem ideal for those undergoing IVF, the fact is this scenario poses significant risks for both the mother and children, such as pre-eclampsia, postpartum hemorrhage, maternal mortality, miscarriage, gestational diabetes, as well as pre-term labor.

Twins also account for a significantly increased percentage of respiratory distress syndrome and neonatal intensive care unit admissions. The likelihood of neonatal mortality had been shown to increase seven-fold for twins over singleton pregnancies. Additionally, the risk of severe handicaps has been shown to increase by 1.7-fold.

For these reasons, the American Society for Reproductive Medicine recommends single embryo transfer in women younger than 35. SET is a process when one good quality blastocyst (or day 5) embryo is transferred back to the patient. The embryos that survive to the blastocyst stage of development are more likely to be strong and healthy. Blastocyst embryos have a much higher chance of implanting than 4 cell (day 2) or 8 cell (day 3) embryos, therefore fewer embryos are required to achieve a pregnancy. Our results have shown that pregnancy rates with SET are as good as those resulting from transferring more embryos.

Women over 35 are faced with a dilemma: the likelihood of pregnancy per embryo transferred declines significantly, and the need to transfer a higher number of embryos is performed to compensate. National guidelines recommend transferring at least three blastocyst stage embryos in women over 40 increasing the likelihood of twin birth. Based on national data, at least 15% of live births were twins in women aged 41 to 42 in 2011.

Elective Single Embryo Transfers and CCS

CCRM offers a means of increasing the likelihood of pregnancy with elective single embryo transfer in women over 35 years of age with the transfer of blastocyst stage embryos that have been vitrified and subsequently warmed after comprehensive chromosomal screening (CCS).

Worldwide research has also shown that IVF pregnancies following embryo cryopreservation and a frozen embryo transfer have more similar outcomes to natural conception pregnancies than IVF pregnancies from a fresh embryo transfer, including increased live birth rates, decreased miscarriage rates, lowered risk of pre-term labor and decreased risk for low birth weight.