Frozen Embryos Make Bigger Babies

When it comes to in vitro fertilization, frozen might be better than fresh, a new study shows. Infants born after being implanted in mothers' wombs as frozen embryos were no more likely than those from fresh stock to be born with congenital defects, the BBC reports; but they were also significantly heavier, and less likely to be born prematurely.

 “We think the reason for the differences is probably positive selection of the embryos for frozen embryo replacement,” the study’s lead researcher said. “Only the very top quality embryos survive the freezing and thawing process.” (More in vitro fertilization stories.)