In a first, researchers have identified the chemicals that makeup the odours of babies' heads, an advance that sheds more light on how newborns attract the attention of caregivers. The researchers, including those from Kobe University in Japan, developed a non-invasive and stress-free method of sampling these odour molecules directly from the heads of the babies.
The study, published in the journal Scientific Reports, looked at both the chemical and psychological aspects of baby-head odours, and how this plays a role in mother-infant kinship. According to the researchers, studying these odours could be utilized in the prevention of issues such as infant neglect, and attachment disorders.
While earlier studies found that olfactory cues were important in the formation and development of mother-baby relationships, very little research identified the essential chemical components of such cues, the team said.
The researchers collected the odour samples from five babies born at Hamamatsu University Hospital in Japan, using monosilica beads that were wrapped inside a cap-shaped net bandage and then placed on the infants' heads.
The study noted that the babies were with their mothers for the duration of the 20 minute sampling period, showing no signs of distress. The researchers also collected samples of the mothers' amniotic fluid odour by suspending monosilica beads in the headspace of glass bottles containing the fluid.
The team identified seven volatile odour components from all the samples, with those from the babies being more distinct from each other than those from the amniotic fluid. The samples which were collected within an hour after birth from two of the babies, looked less similar to each other than those collected two to three days after birth from the other infants.
According to the researchers, this suggested that babies may express more individuality through their head odours soon after birth, compared to a few days later.
When 62 Kobe University students were asked to smell one of the three samples containing the baby's head odour and amniotic fluid samples, and determine which of them was identical to the one they had smelled earlier, they were able to distinguish between the samples.
The study noted that the identification rate was over 70 per cent for all participants when they sampled mixtures with the baby-head odour, and 55 per cent for the amniotic fluid ones.