Levels of the hormone oxytocin circulating in a pregnant woman's body play a critical role in how closely she will bond with her newborn - both emotionally and behaviourally, a new study suggests.
In animals, oxytocin, dubbed "the hormone of love and bonding," is known to be important for the development of good parenting and maintaining close relationships.
Studies have shown that oxytocin appears to have a common role in the behaviour of mammals. In one study with voles (a mouse-size rodent), females with no oxytocin or low oxytocin levels exhibited less licking and grooming behaviour and were slower in retrieving the pups.
Until now there was little evidence to support a role for oxytocin in maternal bonding in humans. Dr Ruth Feldman and colleagues at Bar-Ilan University, Ramat-Gan, Israel, are the first to show that oxytocin is important in the bonding that occurs between mothers and their infants.
The researchers measured oxytocin levels in 62 pregnant women during the first and third trimester and the first month after delivery. They also watched how the mothers interacted with their infants and asked the mothers how they felt and behaved towards their son or daughter.
Hormone tied to behaviour
"We found that initial levels of oxytocin (first trimester) predicted bonding-related thoughts...as well as maternal 'affiliative' behaviour to her newborn," Feldman noted in an email to Reuters Health.
Mothers with higher levels of oxytocin at the beginning of pregnancy engaged in more bonding behaviours after birth, Feldman's group reports in the current issue of Psychological Science.
In addition, mothers who had high levels of oxytocin throughout pregnancy and soon after delivery also engaged in more personalised bonding-related behaviours that facilitated a more exclusive bond with their infants - behaviours and actions not easily duplicated by another person, like singing a special song to the infant or bathing and feeding them in a special way.
Mothers with high oxytocin levels were also more preoccupied by thoughts of checking on the infant, the infant's safety when they were separated and the infant's future.
This study shows that the love hormone oxytocin "functions in humans just like in mammals," Feldman said. "It has a 'sensitising' or 'priming' effect, just like in mammals, so that its elevation across pregnancy possibly prepares women to bond with their infants."
SOURCE: Psychological Science, November 2007. – (Reuters Health)
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