Despite advances in the field of medicine, early pregnancy loss and birth defects continue to persist.

In the U.S, for instance, 15 to 20 out of every 100 women who are aware they are pregnant will have a miscarriage. One in every 33 babies, on the other hand, is born with a birth defect.

A breakthrough in human embryo research, however, may finally shed light on what happens during the earliest moments of human development and this could give scientists better insights on why miscarriages and birth defects occur.

For the first time, scientists have grown human embryos outside the womb for nearly two weeks before the research was put to a stop shortly before it could violate an international ethics standard that restricts experiments on lab-grown embryos to the first 14 days.

It is currently difficult to keep embryos growing in vitro after seven days, the time when they are often implanted after fertilization but researchers were able to keep the embryos growing on a petri days for nearly two weeks before they were abandoned.

The new method through which chemicals and a medium mimicked the human womb to support the continued development of the embryos gave researchers insight on how the embryo starts organizing itself to form into a human being.

"It actually allows us to understand the very first steps in our development at the time of implantation where the embryo, really for the first time, reorganises itself to form the future body," said Magdalena Zernicka Goetz, from the University of Cambridge.

"Those steps we didn't know before so it has enormous implication for reproductive technologies."

As this early period of embryonic development marks the time when embryos generally acquire developmental defects or fail to implant, being able to observe implantation in culture gives scientist the opportunity to learn why early miscarriages occur and why in vitro fertilization has high failure rate. It may also advance treatment of diseases using embryonic stem cells.

"Our findings highlight the species-specificity of these developmental events and provide a new understanding of early human embryonic development beyond the blastocyst stage," the researchers wrote in their study, which was published in journal Nature on May 4.

"Our study establishes a new model system relevant to early human pregnancy loss."

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