In Vitro Fertilization - One Embryo Better Than Two

By Margarita Nahapetyan

For women who undergo in vitro fertilization (IVF), single embryo implant appears to be not only less expensive compared to two or more implants, but is also more effective and successful when it comes to delivering a healthy baby, reports a team of Finnish researchers.

The findings, which are the result of a long-running study, showed that the use of single embryo implantation increased while the live birth rate per woman did not change and the multiple birth rate significantly went down. The new study provides evidence that women started giving preference to a single embryo transfer over the traditional transfer of two or more embryos.

The practice of a single embryo transfer has not been widely used because of fears that there could be lower pregnancy rates per embryo implantation, as well as noticeable increase in the cost of treatments, and more extended time than is required for getting pregnant. However, there is a common belief that multiple pregnancies, which often result from a double embryo transfer during in vitro fertilization, pose an increased risk for health - mainly from complications related to premature deliveries.

For their own study, the researchers from Finland analyzed the data of 1,510 women under the age of 40 who had been the patents of the infertility clinic at Oulu University Hospital. The experts looked at two time periods - between 1995 and 1999, when implantation of a single embryo to the womb was less common (used by 4.2 per cent of women), and between 2000 and 2004, when single embryo transfers had become the more common practice (used by 46.2 per cent of women).

The results showed that the women who had received a single embryo implant were more likely to deliver babies in full term. These women also had birth rates of about 42 per cent, compared to nearly 37 per cent of those who had two or more embryos transferred to their wombs. Single embryo implants also split the rates of multiple pregnancies in half, which can lead to medical complications or lethal outcomes for both babies and their mothers.

In addition, the study revealed that multiple embryo transfers turned out to be very costly in the end, especially when the scientists took into consideration the treatment of health complications due to multiple births. The team found that the total treatment cost in the women who chose single embryo implants was, on average, 5 per cent less per woman, compared to those in the double embryo transfer period. The costs ranged between 2 to 20 per cent less.

More than 3.5 million children have been born worldwide using in vitro fertilization technology since July 25, 1978, when British doctors welcomed the world's first test-tube baby, Louise Brown. The IVF technique involves surgically removing eggs from a woman's ovaries and combining them with a man's sperm in the laboratory. Doctors then pick the best of the resulting embryos - typically one or two - and transfer them into the woman's womb.

The findings should help assure couples who consider in vitro fertilization that choosing to implant just one embryo will provide them with the best possible results, concluded Dr. Hannu Martikainen, Chief Physician of the Division of Infertility and Reproductive Endocrinology at the University of Oulu. "These data should also encourage clinics to evaluate their embryo transfer policy and adopt eSET [elective single embryo transfer] as their everyday practice for women younger than 40."

The scientists published their findings in the online edition of the reproductive medicine journal Human Reproduction.