Study participants with an extremely low birth weight were 4.5 times more likely to develop psychiatric disorders.
But it is not all bad news for very low-birth-weight babies; the research team - led by Dr. Ryan Van Lieshout, professor of psychiatry and neurosciences in the Michael G. DeGroote School of Medicine at McMaster University in Canada - also found they are at lower risk of alcohol or substance abuse.
According to the Centers for Disease Control and Prevention (CDC), around 8% of babies in the US were born a low birth weight (less than 2,500 g) in 2013, while around 1.4% of babies were born a very low birth weight (less than 1,500 g).
The most common driver behind low birth weight is premature birth; approximately 7 in 10 low-birth-weight babies in the US are born preterm. Other causes include fetal growth restriction and infection during pregnancy.
Past studies have established that babies with a low birth weight are at increased risk of numerous health problems later in life, including obesity, hypertension, diabetes and heart disease. But how does low birth weight affect mental health in adulthood?
Very low-birth-weight babies up to 4.5 times higher risk of psychiatric problems
To find out, Dr. Van Lieshout and his team analyzed the presence of psychiatric disorders among 84 adults who were born an extremely low birth weight (less than 1,000 g) and 90 adults who were born a normal birth weight.
All participants were born between 1977 and 1982 in Ontario, Canada, and were in their early 30s at the time of assessment.
The researchers found that the participants with an extremely low birth weight were three times less likely to develop a substance or alcohol use disorder than those with a normal birth weight.
However, low-birth-weight participants were 2.5 times more likely to develop a psychiatric disorder in adulthood - such as depression, ADHD (attention deficit hyperactivity disorder) and anxiety than those born a normal weight, according to the team.
In addition, low-birth-weight participants whose mothers received full antenatal steroid treatment just before birth were found to be almost 4.5 times more likely than normal-birth-weight participants to develop psychiatric problems, and they also had no reduced risk for substance or alcohol use disorders.
Commenting on their findings, Dr. Van Lieshout says:
"Importantly, we have identified psychiatric risks that may develop for extremely low-birth-weight survivors as they become adults, and this understanding will help us better predict, detect and treat mental disorders in this population."
In December 2014, Medical News Today reported on a study by researchers from Northwestern University, IL, that found low-birth-weight children may have poorer academic outcomes than children born a normal weight.