One embryo works as well as two for IVF: studies

Using a single embryo for in-vitro fertilization is just as likely to result in a successful pregnancy as transferring two embryos, while reducing the chance of a higher-risk twin conception, according to research released on Friday.

Women pregnant with twins, triplets or quadruplets are at greater risk of serious health complications than are women carrying just one fetus.

In addition, delivering multiple babies carries a higher risk of premature labor and low birth weight, both of which can be fatal to infants.

If they survive, premature babies are more likely to suffer from neurological conditions like cerebral palsy.

With IVF, also known as test-tube baby technology, a women's egg and her partner's sperm are combined in a lab dish. Resulting embryos are implanted in the woman's uterus or sometimes frozen for later use.

To increase the chance of success, fertility clinics often implant several embryos at the same time.

But two studies, published in the December issue of Fertility and Sterility, found that implanting one embryo worked as well as two for achieving a successful pregnancy.

Researchers in Seattle examined the results of more than 200 IVF cycles where the patients had either one or two embryos transferred.

The patient and cycle characteristics were similar for the two groups.

The study revealed that while implantation and live birth rates were virtually the same for the two groups, there was a significant difference in the number of twins.

Similar results were published from an Australian study.

There, patients who had a single embryo transfer had nearly as high a pregnancy rate, but a much lower incidence of twins than patients who transferred two embryos.

"This research shows the continued progress we are making in addressing the problem of multiple births. These studies will help us move to the goal of singleton pregnancies for all our patients" Dr. William Gibbons, president of the Society for Assisted Reproductive Technology, said in a statement.