Babies of teenage mothers and infants who have a low birth weight have a higher risk of committing suicide later in life than other children, Swedish scientists said Friday.

In a study of more than 700,000 young adults, researchers at the Karolinska Institute in Stockholm found that infants born to young mothers or those who weighed 4.4 pounds at birth were twice as likely to try to kill themselves.

“We need to monitor and support young mothers during pregnancy and to follow-up their newborn children to help them with emotional and practical support when needed,” Dr. Danuta Wasserman, who worked on the study, said in an interview. “Prevention needs to start before a child is born.”

Social and economic conditions, stress during pregnancy, poor parenting and poor maternal health are thought to be contributing factors to an increased suicide risk.

The researchers studied young adults in Sweden who were born between 1973 and 1980 and monitored them until 1999 to identify factors associated with suicide or attempted suicide.

Almost 2,000 men and more than 4,700 women in the study attempted suicide. Nearly 400 men and 166 women succeeded.

Children from big families or whose mothers had a low level of education also had a higher risk of taking their own life. But having a mother who was 29 years or older at the time of birth seemed to have a protective effect against suicide.

In a commentary on the research, Dr. Maria Oquendo and Dr. Enrique Baca-Garcia of Columbia University in New York said it was another step forward in understanding suicidal behavior.

They added that it opens a new line of inquiry focused on the interaction between conditions in the womb and at birth and additional factors, such as the parents’ psychiatric and suicide history and parenting styles.

SOURCE: The Lancet, September 25, 2004.