Multiple pregnancy is, along with ovarian hyperstimulation, the most significant complication in fertility treatments.
Most couples that go through assisted reproduction techniques consider multiple pregnancies to be desirable or the lesser evil. However, pregnancies of twins and even more so triplets are associated with a series of complications that challenge the pregnancy ending in the birth of a healthy baby. Let us not forget that the birth of a healthy baby is the only objective of assisted reproductive techniques.
The most important problem based on the frequency and seriousness is premature birth. In twin pregnancies, prematurity occurs in over half of all cases, whereas when we consider triplets, almost all of births end before the 37th week and are therefore considered premature.
Prematurity not only means that the newborns will need special care. The complications associated with premature babies may endanger their lives or cause long-term effects.
The main problem is that the chances of success are almost always better when we take on a certain risk of multiple pregnancy in In Vitro Fertilization (IVF) techniques when we transfer a higher number of embryos. In theory, the more embryos we transfer, the greater the chances of getting pregnant and the greater the risk of multiple pregnancy.
In recent years we have been able to improve the pregnancy rates while transferring fewer embryos. Triplets have practically disappeared from IVF treatments and the cases in which we recommend transferring only one embryo are more and more frequent. This has become possible thanks to the improvements made to treatments on all levels.
We have optimized the ovarian stimulation, egg collection, embryo transfer and especially the laboratory processes with culture techniques that allow us to take the embryos all the way to the blastocyst stage by selecting those with the highest implantation capacity. The selection of the best embryos is the key to transferring a lower number and nowadays we are perfecting techniques to be able to reliably make this selection. We can already analyze the embryos in a comprehensive way and determine whether they have chromosomal alterations by studying the complete genetic
material (Preimplantation Genetic Diagnosis with aneuploidy screening through array-CGH techniques) by ruling out the embryos chosen to not implant and improving the chances of transferring one suitable embryo. At the same time, in the near future we will be able to determine the embryo’s implantation capacity by studying the substances that it produces during its culture and improving even more the chances of pregnancy after transferring one single embryo.
This has caused us to now recommend the transfer of one single embryo to many patients who due to their good prognosis, (under 40 years old and with “good” embryo quality) are going to have a very high chance of becoming pregnant without risk of multiple pregnancy.
The transfer of one single embryo should be the first choice for a significant percentage of patients that go through IVF, however, as always in patient-centered healthcare, the couples’ opinion should be taken into consideration along with the basic emotional and personal connotations. This way, the patients, embryologists and doctors should jointly and calmly evaluate the best decision by the time of embryo transfer.