Babies can be fickle regarding their eating, as they often demonstrate by throwing the foods they don’t like on the floor. But, for the first time, scientists could record babies’ reactions to various tastes and smells while in the womb. These reactions were marked by different facial expressions.

This study from Durham University’s Fetal and Neonatal Research Lab in the UK worked with 100 pregnant women, giving them 4D ultrasounds while the mothers ate one of two foods – carrots or kale. The fetuses’ facial expressions changed considerably after the mother ingested each of these foods: When the mothers ate carrots, generally the fetuses displayed what researchers call a “laughter-face,” whereas the ingestion of kale caused the fetuses to show a “cry-face.”

The mothers took a single 400mg capsule of carrot or kale powder for the experiment. Twenty minutes later, researchers performed the 4D scans. No other foods were consumed before the scan to ensure accurate findings. The scans showed that just a tiny amount of each flavor was enough to cause the fetus to react.

As humans, we interpret flavor through both taste and smell. But for fetuses, it’s suggested that the inhalation and swallowing of amniotic fluid are what helps them identify flavor. This shows promise that what a mother eats during pregnancy may affect a child’s food preferences later in life. Mothers, take note, you may be able to eat your way to developing your own healthy eater!

“A number of studies have suggested that babies can taste and smell in the womb, but they are based on post-birth outcomes while our study is the first to see these reactions prior to birth… It was really amazing to see unborn babies’ reaction to kale or carrot flavours during the scans and share those moments with their parents.” – Beyza Ustun, lead researcher on the study.

The study may help scientists understand how taste develops and how that memory is stored throughout a child’s life. This has led to a follow-up study with the same babies after birth to examine if and how their flavor exposure in the womb has influenced their food preferences in childhood.