Single Embryo In-Vitro Fertilization as Successful as Multiple Implantation

Many couples experiencing fertility issues who opt for In-Vitro Fertilization (IVF) presume that the implantation of multiple embryos will increase their chances having a healthy baby. However, results of a recent analysis published in the New England Journal of Medicine indicates that the use of two or more embryos actually increase the likelihood of a multiple birth pregnancy.

The belief that multiple embryos increase the chances for parenthood comes from the early days of IVF. During this time, doctors routinely implanted half a dozen or more embryos into a woman’s womb in hopes of increasing the odds that at least one would grow into a healthy baby. However, over the years, the procedure has greatly improved, which has led to better results using fewer embryos.

The new study serves as a follow-up to research performed in 2004 that yielded similar results, and also supports the growing concern over the health risks linked to multiple births that affect both mothers and babies. Mothers who experience multiple birth pregnancies have a greater risk of developing gestational diabetes, which is a diabetic condition brought on by the pregnancy itself, as well as bleeding and pre-eclampsia (a condition characterized by high blood pressure and the presence of protein in the urine). The increased health risks for babies include cerebral palsy, which causes permanent disorders in the development of movement and posture, as well as birth defects, developmental delays, and even death.

The latest analysis performed by Swedish researchers followed its female subjects for a longer period of time, as well as through more embryo implantations. The research team found that the use of one embryo instead of two is almost as successful, and significantly reduces the risk of multiple births.

For the study, Dr. Ann Thurin-Kjellberg of Gothenburg University and her colleagues analyzed the records of 661 women who underwent implantation with a fresh embryo on their first try. For those who were not successful the first time, implantations with one or two frozen embryos were performed. The team continued to follow those women whose earlier IVF procedures failed, up to a total of four attempts.

Of the women who received one embryo, 44 percent conceived on the first attempt and gave birth to live babies. For the women who got two embryos, 51 percent had a successful attempt. However, only 2.3 percent of the women who received the single embryo had multiple births, compared to 27.5 percent of those who had multiple embryos implanted. There were a total of four sets of twins born to the single-embryo mothers, versus 51 sets of twins, and one set of triplets, born to the double-embryo mothers. Although it is common knowledge that the majority of twins born will survive, it is of interest to note that their medical expenses over the first five years of life are usually much higher.

Another finding of the analysis was that women receiving one embryo were shown to be much less likely to have babies born prior to 37 weeks of gestation, at a rate of 11.8 percent, compared to 25.5 percent for the group receiving two embryos.

Although the researchers concluded that there is little downside but plenty of upside to transplanting one embryo at a time, the use of multiple embryos in IVF remains a subject of debate. Advocates of the use of multiple embryos argue that multiple implants boost the odds for a success, as well as for multiple births, and that it is much less expensive than having IVF performed multiple times when early attempts fail. In addition, avoiding the stress and disappointment of a failed attempt is a key factor for some.