Infants born prematurely show less interest in other people compared to infants born full-term, when tested at six months and 12 months, according to a new study at Kyoto University in Japan.
The findings shed new light on the links between premature birth, development of social communication skills, and ultimately autism.
“Autism occurs from a mix of genetic and environmental factors. Preterm infants get a tremendous amount of stress in the early days of birth, because the environment is profoundly different from that of the womb,” said head researcher Dr. Masako Myowa-Yamakoshi.
“This make them much more prone to developmental difficulties, even if they seem perfectly fine when they leave the hospital.”
Lead author Masahiro Imafuku noted that a lack of interest in social stimuli, such as another person, could be an early indication of whether preterm infants are following a path toward atypical social development.
For the study, the research team simultaneously showed videos featuring people and geometric patterns to six and 12-month old infants, watching to see which videos the infants preferred. Gaze signifies interest, meaning that the longer time spent looking at the people video, the more interest there is in others.
Their findings revealed that full-term infants spent more time looking at the people video, but a significant number of preterm babies at term-equivalent ages showed more interest in the geometric motion.
In a second experiment, the researchers analyzed how well infants could follow the gaze of other people. “Being able to follow where other person is looking is related to understanding of others’ intention, and of language acquisition,” said Imafuku.
Similar to the findings of the first experiment, 6-month-old full-term infants followed the gazes of people in the video, whereas preterm infants had more difficulty.
Interest in other people and following eye directions develops in most preterm infants from 6 to 12 months. This, when coupled with another study, indicates that the nervous systems of several preterm babies may develop in significantly different ways from that of full-term babies in the first year of life.
In another study, the researchers found that preterm babies cry with a shrill, high pitch. This is because the activity of the vagus nerve is weaker in preterm infants.
“The low activity of the vagus nerve makes the vocal cords contract excessively,” said Yuta Shinya, who authored the second study.
“The distinct shrill of preterm babies reflects the activity of this nerve, which is related to the regulation of heart and throat function, health, and cognitive abilities. We’re looking into whether the shrill cries correlate with atypical cognitive development in infancy.”
“Preterm birth incidence is rising in developed countries like Japan, since people increasingly give birth at an older age, and given assumed risks with IVF,” says Myowa-Yamakoshi. “We hope that studies like ours contribute to earlier diagnoses, so that we can offer appropriate support at as early a stage as possible.”
Source: Kyoto University