SAN FRANCISCO – Stanford University researchers who studied and photographed human embryos for the first five days after fertilization say they have found a way to accurately predict which embryos will reach an important developmental milestone – and may be the most likely to lead to healthy pregnancies.
The study of 242 frozen, one-cell embryos, which was published Sunday in the online journal Nature Biotechnology, is one of the first and best to capture on video the earliest stages of human development.
The videos are actually time-lapsed photos taken at five-minute intervals, and they clearly show the first cell division through to the development of a blastocyst, a hollow structure that contains a clump of cells that will become the fetus. The Stanford researchers were able to determine with 93 percent accuracy which newly fertilized eggs would become blastocysts, and which would stop growing and die before they reached that stage.
Their findings could be significant for women trying to get pregnant through in vitro fertilization. Further studies need to be done, the scientists said, but they believe their research could allow specialists to determine only two or three days after fertilization which embryos are most likely to lead to successful pregnancies.
That could eliminate the need to implant two or more embryos at once to increase the chance of a single birth. And it could allow specialists to implant sooner after fertilization, which most doctors believe leads to fewer complications and better chances of a pregnancy.
“If you can predict blastocyst stage, you can transfer fewer embryos earlier,” said Renee Reijo Pera , an author of the study and director of the Center for Human Embryonic Stem Cell Research and Education at Stanford’s Institute for Stem Cell Biology and Regenerative Medicine .
“We could reduce adverse effects,” Pera said. “We could reduce these multiple births and increase the chance of a single baby birth. And we could reduce miscarriages.”
The study was paid for primarily through a large anonymous donation, along with money from the March of Dimes and the Stanford Institute for Stem Cell Biology. Federal funds are not permitted to go toward research in which human embryos are destroyed. The embryos in the study were created at an in vitro fertilization program in Illinois that is now closed; the patients gave consent for their embryos to be used in research.