A case for elective single embryo transfer
After egg and sperm are used to produce embryos in the IVF lab, you may have more than one viable embryo to transfer or cryopreserve. Rather than rely on a fresh embryo transfer without any diagnostic tests, many patients now choose to use preimplantation genetic screening (PGS) to select their best embryo. PGS enables prospective parents to transfer a single embryo without lowering the chances for conception. The improvements to ovarian stimulation protocols, cryopreservation techniques and luteal phase support have also improved and support single embryo transfer. Cryopreservation of embryos for replacement in a later cycle allows sufficient time for genetic tests to be performed and for the uterus to recover from the negative effects of ovarian stimulation, further improving success rates.
During a traditional IVF cycle, fresh embryos were transferred back into the uterus in the hopes that they would implant. The uterus, recently exposed to ovarian stimulation medications used to obtain numerous eggs, would often be non-receptive to the embryos. This could result in wasting the patient’s best embryos, or only embryos.
Back in the days of low implantation rates, when fewer than half of transferred embryos would actually implant, two or more embryos were routinely transferred in order to increase the chance that at least one would result in a baby. This practice is largely obsolete at modern centers like the Fertility Center of Las Vegas, where implantation rates are high enough to support single embryo transfer in most patients. Today, 70% of transferred embryos result in embryo implantation (a fetal heartbeat) at the best centers, negating the need to transfer two embryos.
Single embryo transfer mitigates the risk of multiples
In 2009, the United States Centers for Disease Control and Prevention (CDC) reported that 2.7% of non-IVF infants were born as twins, while 44% of IVF infants were twins, for a 16-fold risk increase. Worse, the risk of an infant being in a high-order multiple birth (triplets or greater) following IVF was 47-fold greater in IVF pregnancies than in non-IVF pregnancies.
The CDC also reported that the risk of being born preterm ( < 37 weeks gestation) was 14% for singletons, 65% for twins, and 97% in high-order multiple pregnancies. The risk of having low birth weight ( < 2500g birth weight) similarly increased from 9% in singleton pregnancies, to 57% in twin pregnancies, and 96% of high-order multiple births.
Preterm birth is associated with numerous increased risks, including:
It is widely recognized that the best means of reducing the risks associated with multiple birth is to transfer single embryos.
Putting 1.6% into perspective
The increased risk of being born as a twin might not seem so bad at first. For example, the risk of infant death is 1.2% for a singleton, and 2.8% for a baby born as a twin. Although the risk is more than doubled, the extra 1.6% risk of death might not seem like so much. Let’s compare that extra added risk to the risks associated with some other dangerous practices or occupations.
The added mortality risk of being born as a twin is:
- 940 times the risk of death from riding a motorcycle for one year.
- 890 times the risk of death from skydiving.
- 640 times the average mortality of firefighters for one year.
- 150 times the average mortality risk of serving as a police officer for one year.
- 9 times the risk of serving a combat tour in Iraq in 2008.
If you would not want your children serving in combat, then you probably should not want them being born as twins, either.
Maternal risks of multiples
-Dr. Carrie Bedient
Multiple birth also increases risks to the mother. While the risk of maternal death is numerically low, 0.007% in singleton births and 0.18% with triplets, that is still a 25-fold increase. The risk of needing a c-section delivery is increased four-fold, as is the average length of hospital stay.
These added medical risks associated with multiple births can be partly measured in medical costs. It has been shown that the added costs of multiple pregnancies caused by fertility treatments is almost four times the total fees collected by fertility centers for all IVF cycles in the United States. That’s just the added costs of multiples, beyond the average costs of singleton births.
Financial weight of multiples
In 2010, the average medical costs for a singleton birth was $21,000, while the average twin cost $105,000, and the average triplet cost $407,000. Keep in mind, these are just the medical costs through the first 30 days of life. These costs do not include long-term care associated with the increased risks discussed above (cerebral palsy, blindness, etc.), nor do they include non-medical costs, such as a larger stroller, a larger vehicle, a larger home, etc.
For these reasons and more, single embryo transfer is almost always the right answer at a modern fertility center. Contact us for a consultation at our Las Vegas fertility center.