Babies ‘react more favourably’ to smell of foods mothers ate late in pregnancy

Mothers who want their toddlers to eat their greens should consume these food items during the late stages of pregnancy, researchers have said.

It follows a study which found that new-born babies showed a positive response to the smell of foods they were exposed to in the womb.

The research, led by Durham University, studied the facial expressions of three-week-old babies whose mothers had regularly taken either kale or carrot powder.

Infants who had been exposed to carrot capsules ingested by their mothers were noted to react favourably to the smell of carrot.

Similarly, those whose mothers had taken kale powder capsules while pregnant reacted positively to that vegetable’s scent.

Professor Nadja Reissland, an expert in foetal and neonatal research whose study of the effect of smoking on unborn babies hit the headlines in 2015, was a lead author on this study.

She said: “Our analysis of the babies’ facial expressions suggests that they appear to react more favourably towards the smell of foods their mothers ate during the last months of pregnancy.

“Potentially this means we could encourage babies to react more positively towards green vegetables, for example, by exposing them to these foods during pregnancy.”

She said there was a tendency for weaning babies to be given sweeter foods, such as mashed carrot, pears or bananas, but babies exposed to more bitter greens might develop a taste for healthy, more bitter greens if the mother ate them in pregnancy.

Professor Reissland said: “If the mother eats the bitter, healthy greens, that might get their children to like and accept them later.”

Unborn babies have a very sensitive sense of smell, she said.

This study of 32 babies from the north-east of England followed up a 2022 research paper where 4D ultrasound scans showed foetuses smiling when their mothers ingested carrots and grimacing when exposed to kale.

For the latest study, the babies were only given swabs of either carrot or kale to smell, but nothing was put in their mouths as they were too young to be exposed to tastes.

Scientists then analysed the video to monitor the babies’ reactions and compared these reactions with those seen before they were born to understand the effects of repeated flavour exposure in the last trimester of pregnancy.

The research team found that, from the foetal to new-born period, there was an increased frequency in “laughter-face” responses and a decreased frequency in “cry-face” responses to the smell the babies had experienced before birth.

Research co-lead author Dr Beyza Ustun-Elayan said: “Our research showed that foetuses can not only sense and distinguish different flavours in the womb but also start learning and establish memory for certain flavours if exposed to them repeatedly.

“This shows that the process of developing food preferences begins much earlier than we thought, right from the womb.

“By introducing these flavours early on, we might be able to shape healthier eating habits in children from the start.”

The research also included scientists from Aston University and academics in France.

It is published in the journal Appetite.