Fetuses smile at carrots, but wave at streets, study finds


While it’s well known that some babies aren’t big fans of greens, a new study suggests that such dietary preferences may be formed before birth.

Fetuses produce more “laughing faces” when exposed to the taste of carrots consumed by their mothers in the womb and more “crying faces” when exposed to street food, according to a study published in the journal Psychological Science. on wednesday

“We decided to do this research to understand more about the fetus’s ability to taste and smell in utero,” lead researcher Beyza Ustun, a graduate researcher in the Fetal and Neonatal Research Lab at Durham University in the United Kingdom, told CNN by email on Thursday.

While some studies have suggested that babies can taste and smell in the womb using postnatal results, “our study is the first to show direct evidence of fetal reactions to tastes in utero,” Ustun added.

“The findings show that fetuses in the last 3 months of pregnancy are mature enough to distinguish different flavors transferred from the mother’s diet.”

The study looked at the healthy fetuses of 100 women aged 18 to 40 who were between 32 and 36 weeks pregnant in the North East of England.

Of these, 35 women were included in an experimental group that consumed an organic kale capsule, 35 were included in a group that took a carrot capsule, and 30 were included in a control group that was not exposed to each other. the taste

Participants were asked not to consume any food or flavored beverages 1 hour prior to scanning. The mothers also did not eat or drink anything containing carrots or kale on the day of their test to ensure that it did not affect the results.

While adults may say the taste of carrots is “sweet”, kale was chosen because it tastes more bitter to children than other green vegetables such as spinach, broccoli or asparagus, according to the study.

After a 20-minute waiting period after consumption, the women underwent 4D ultrasound scans, which were compared to 2D images of the fetus.

The pulling of the corner of the lips, suggestive of a smile or laugh, was significantly greater in the carrot group compared to the kale and control group. Movements such as raising the upper lip, pulling down the lower lip, pressing the lips and their combination – a suggestive crying face – were much more common in the street group than in the other groups.

“By now, we all know (a) the importance of a healthy diet for children. There are many healthy vegetables that unfortunately have a bitter taste, which is usually not attractive to children”, said Ustun. He added that the research suggests that by manipulating the mother’s diet during pregnancy “we could change food preferences during pregnancy even before birth”.

“We know that a healthy diet during pregnancy is essential for the health of children. And our evidence may help to understand that adjusting the mother’s diet can promote healthy eating habits in children,” he added.

Advances in technology have led to better images of fetal faces in the womb, according to Professor Nadja Reissland, head of Durham University’s Fetal and Neonatal Research Laboratory. Reissland, who oversaw the research, developed the Fetal Observable Movement System (FMOS), with which 4D ultrasound scans were coded.

“As technology advances, ultrasound images are better and more accurate,” he told CNN, which “allows us to code fetal facial movements in frame-by-frame detail and over time.”

The researchers have now begun a follow-up study with the same babies after birth to see if the flavors they experienced in the womb affect their acceptance of different foods during childhood, according to a press release.

All the women involved in the study were white and British.

“More research needs to be done with pregnant women from different cultural backgrounds,” Ustun told CNN. “For example, I come from Turkey and in my culture, we like to eat bitter food. It would be very interesting to see how Turkish children would react to the bitter taste.’

He added, “Genetic differences in taste sensitivity (being a supertaster or a nontaster) may influence fetal responses to bitter and nonbitter tastes.”