Being born underweight leads to a shy and cautious wallflower-type personality, a McMaster University researcher has found.

People who feel inhibited in social situations, aren’t as talkative and are more anxious about taking risks, may not get these traits from their upbringing, said Louis Schmidt, lead author of the recent study and a professor of psychology, neuroscience and behaviour.

Such timidness potentially affects a person’s future and could lead to “delays in occupational obtainment, delays marrying and having children,” he added.

The study, which was published in the July issue of Pediatrics, harks back to the nature versus nurture debate about how someone’s personality gets developed.

“What plays a bigger role?” he asked. “We’re looking at how early life events and early experiences impact brain development.”

Schmidt hypothesized these personality traits could be because the underweight babies spent so much time in a neonatal unit - some for months at a time - and didn’t get the same chance to bond with their parents as normal-weight babies.

Underweight babies also are at risk for other medical problems, like compromised immune systems, and tend to face a higher rate of diabetes and heart disease as adults.

This study looked at 71 young adults, born in southern Ontario in the late 1970s and early 1980s who were underweight at birth, and compared them to 83 people who were born around the same time and region at a normal weight.

The young adults were asked a series of questions about how social they are and how likely they are to take risks.

Underweight babies typically weigh less than 2,500 grams (5.5 pounds). In Canada, one of every 16 babies are born underweight.

Schmidt’s study found the lower the birth weight, the more shy and inhibited the person is as an adult.

They have also been studying brain activity and hormones in these young adults, both those who were born underweight and at a normal weight.

The findings, which are currently under review, show being born underweight could also lead to an inability to handle stress, Schmidt said.

Source: Hamilton Spectator, Canada
http://www.thespec.com/News/Local/article/410333