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Fetuses React to Taste and Smell

New study uses 4D ultrasounds to capture unborn babies' reactions to carrot and kale

Holden Galusha

A recent, first-of-its-kind study from Psychological Science has returned direct evidence that fetuses experience taste and smell in the womb and react accordingly.

Using 4D ultrasounds to capture the fetuses’ facial expressions, researchers at the Fetal and Neonatal Research Lab at Durham University scanned 100 pregnant women twice, at 32 weeks and 36 weeks, shortly after eating carrot and kale tablets. Overall, the unborn babies consistently made “laughter faces” and “crying faces” in response to carrot and kale flavors, respectively, and compared against a control group of fetuses who were not exposed to any flavors. These observations are the first direct evidence that unborn babies experience taste and smell in the womb. Similar studies conducted in the past were done postpartum, which meant there was a degree of uncertainty in the hypotheses that this new study has eliminated.

Co-author Najda Reissland, head of the Fetal and Neonatal Research Lab and lead author Beyza Ustun’s supervisor, commented, “This latest study could have important implications for understanding the earliest evidence for fetal abilities to sense and discriminate different flavors and smells from the foods ingested by their mothers.”

To follow up, the team will study the same babies post-birth to see if their earlier exposure to carrot and kale will affect how they accept the foods outside the womb. Research co-author Jackie Blissett of Aston University said, “It could be argued that repeated prenatal flavor exposures may lead to preferences for those flavors experienced postnatally. In other words, exposing the fetus to less ‘liked’ flavors, such as kale, might mean they get used to those flavors in utero. The next step is to examine whether fetuses show less ‘negative’ responses to these flavors over time, resulting in greater acceptance of those flavors when babies first taste them outside the womb.”

The research team hopes that this technique of using 4D ultrasounds to observe fetal reactions could pave the way to monitoring their reactions to other actions taken by their mothers, such as smoking, and even how they react to mental health issues.