WASHINGTON (Reuters) – Researchers using a microscope and time-lapse photography believe they have developed a method for predicting which test-tube embryos are the most likely to develop properly, and are licensing development of a commercial test.

Their findings, published in the journal Nature Biotechnology, also provide some new insights into the development of days-old embryos, such as how babies inherit some genes from the mother and some from the father.

They said the new test could help fertility clinics pick the best embryo to implant in the womb.

This would save mothers from having several treatments and help improve on the current method of implanting multiple embryos to try to get one pregnancy and risk multiple births in the process. "Our results shed light on human embryo development," wrote Renee Reijo Pera of Stanford University in California and colleagues. "Our methods and algorithms may provide an approach for early diagnosis of embryo potential in assisted reproduction."

So called test-tube babies are conceived by uniting egg and sperm in a lab dish and transferring the embryo into a woman's uterus to develop. Most do not develop properly and labs have been looking for ways to improve their success rate.

Although it is not recommended, some IVF clinics will implant more than one embryo into the mother's womb – leading to the birth of triplets, quadruplets and even more. Such babies almost always are born too early and face lifelong health problems. All pregnancies are tenuous, even those achieved the old fashioned way. The March of Dimes, a charity founded to battle birth defects, estimates that as many as 50 percent of all pregnancies end in miscarriage – most often before a woman knows she is pregnant.