Babies In Womb React To Tastes And Smells
With the latest spate of public debates over the viability of unborn babies perhaps serving as an ironic backdrop, scientists in the United Kingdom have recorded the first direct evidence that babies react differently to various smells and tastes while still in the womb.
A study led by Durham University’s Fetal and Neonatal Research Lab in England took 4D ultrasound scans of 100 pregnant women to see how their unborn babies responded facially after they were exposed to the flavors of foods eaten by their mothers.
Results of the research were published in the journal Psychological Science.
Researchers tracked the fetuses’ reactions to the flavors of either carrot or kale almost immediately after the flavors had been ingested by the mothers.
The faces of the fetuses exposed to carrot demonstrated “laughter” responses while those exposed to kale looked as if they were crying.
The findings, the study said, could considerably broaden the understanding of how human taste and smell receptors develop.
The Durham researchers also believe that what pregnant women eat may well influence the taste preferences of a baby after birth.
Humans experience flavor through a combination of taste and smell. So, it’s believed fetuses also experience taste and smell by inhaling and swallowing the amniotic fluid in the womb.
“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,” said study lead Beyza Ustun, a Durham postgraduate researcher.
“As a result, we think that this repeated exposure to flavors before birth could help to establish food preferences post-birth, which could be important when thinking about messaging around healthy eating and the potential for avoiding ‘food-fussiness’ when weaning.”
Added Ustun: “It was really amazing to see unborn babies’ reaction to kale or carrot flavors during the scans and share those moments with their parents.”
The research team — which included scientists from Aston University, Birmingham, UK, and the National Centre for Scientific Research-University of Burgundy, France — scanned the mothers, aged 18 to 40, at both 32 weeks and 36 weeks of pregnancy to monitor the fetal facial reactions to the kale and carrot flavors.
Mothers were given a single capsule containing approximately 400mg of carrot or 400mg kale powder about 20 minutes before each scan and were asked not to consume any food or flavored drinks one hour before scanning.
The mothers also did not eat or drink anything containing carrot or kale on the day of their scans.
When compared with fetuses in a control group not exposed to either the carrot or kale flavor, facial reactions observed in both flavor groups revealed that exposure to even a small portion of carrot or kale flavor was enough to stimulate a fetal reaction.
“Previous research conducted in my lab has suggested that 4D ultrasound scans are a way of monitoring fetal reactions to understand how they respond to maternal health behaviors such as smoking, and their mental health including stress, depression, and anxiety,” explained research co-author and head of Durham’s Fetal and Neonatal Research Lab, Prof. Nadja Reissland.
“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,” she said.
“Looking at fetuses’ facial reactions we can assume that a range of chemical stimuli pass through maternal diet into the fetal environment” offered study co-author Prof. Benoist Schaal of the National Centre for Scientific Research-University of Burgundy in France. “This could have important implications for our understanding of the development of our taste and smell receptors, and related perception and memory.”
The study team says the findings could provide additional information given to mothers about the importance of taste and healthy diets during pregnancy.
The researchers have already started a follow-up study with the same babies after being born to see if the influence of flavors they experienced in the womb ended up affecting their acceptance of different foods going forward
“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,” said research co-author Prof. Jackie Blissett of Aston University. “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 they first taste them outside of the womb.”