Teenage mothers don't respond in the same way physiologically as adult mothers do to the sound of babies crying. That's according to Jennifer Giardino and colleagues who say the difference is probably due to the neural immaturity of the teenage mothers' brains.
Fifty-six recently-pregnant teenage mothers (average age 18 years), 58 age-matched, non-parent teenage girls, and 49 recently-pregnant adult mothers (average age 31 years) were played audio tapes of babies crying either with hunger or pain. The participants were asked to indicate how the cries made them feel, and their heart rate and cortisol levels were also recorded, the latter via a saliva swab. Afterwards the mothers were also videoed playing with their own baby for 15 minutes.
From a physiological perspective there was no difference in the way the teenage mothers and the teenage non-mothers responded to the sounds of the babies' cries. However, the teenage mums reported feeling more sympathy and being more alert to the babies' cries.
When the teen mums were compared with the adult mothers, the opposite pattern emerged. The teenagers said the cries made them feel the same way as the adult mothers did, but physiologically there were differences. The adult mothers showed increased heart rate and cortisol in response to the cries, whereas the younger mothers did not.
These physiological differences appeared to be reflected in the way the two groups of mothers played with their children - the teenage mothers spent less time interacting with their child when videoed, and more time looking away.
The overall pattern of results held even after controlling for the time of day that testing took place and the socio-economic status of the fathers.
Taken together, the researchers said their results suggest teenage mothers are less attuned to infants behaviourally and physiologically, perhaps due to the fact their own brains are still developing. "In addition to the social and economic challenges confronting teenage mothers that may explain some of the present results," they wrote, "there is also a substantial literature indicating that the medial prefrontal cortex, the brain region important for planning and executive functioning, is still developing through the teenage years..."
Giardino, J., Gonzalez, A., Steiner, M. & Fleming, A.S. (2008). Effects of motherhood on physiological and subjective responses to infant cries in teenage mothers: A comparison with non-mothers and adult mothers. Hormones and Behaviour, 53, 149-158.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.