USA TODAY - We know babies love looking at the faces of their mom or dad. Now, for the first time, researchers have discovered that this preference develops in the womb several weeks before birth, according to a study published Thursday.
By projecting light through the uterine wall of pregnant mothers, British scientists found that 34-week-old fetuses will turn their heads to look at face-like images.
"We have shown the fetus can distinguish between different shapes, preferring to track face-like over non-face-like shapes," said psychologist Vincent Reid of Lancaster University in the United Kingdom, a co-author of the study. "This preference has been recognized in babies for many decades, but until now exploring fetal vision has not been attempted."
The findings, which appeared in the peer-reviewed journal Current Biology, were also the first to show it's possible to explore sight and cognition in babies before birth.
Researchers projected two patterns of three dots in the shape of a triangle through the uterine wall of 39 pregnant mothers: One pattern was in the shape of eyes and a mouth and the other was upside down. Scientists then measured how the fetus responded using high-quality, 4D ultrasound.
The ultrasound showed developing babies turned their heads to look more often at upright, face-like stimuli than those presented to them upside down.
"The behavior of the fetus’ here shows that they did see the shapes that we presented as they distinguished between the two patterns," said study co-author Kirsty Dunn, also of Lancaster University.
"It turned out that they responded in a way that was very similar to infants," Reid added.
And while fetuses' eyes are likely to be closed most of the time, the ultrasound scans often showed them blinking.
Dunn said researchers knew it was possible for light to travel to the fetus and that eyes functioned before birth, but this study allowed a deeper understanding of sight development.
"We have been able to explore the use of all the fetal senses except vision up until now," Dunn said. "This includes touch, taste, smell, balance and hearing. But we wanted to move forward with understanding fetal vision."
Neither mothers nor fetuses were in danger during the research. "We were very careful and made sure that the light was bright enough to enter the womb but not too bright as to be unpleasant or aversive for the fetus,” Reid said.
In general, though, he discourages pregnant mothers from shining bright lights into their bellies.
Copyright 2017 USA TODAY