FRIDAY, Jan. 25 (HealthDay News) -- Men who were short at birth are more likely to attempt suicide and more than twice as likely to attempt violent suicide than men who were normal-length newborns, a new study says.

Violent suicide includes hanging, the use of a gun or a knife, jumping from a height or in front of a vehicle, or drowning.

The increased risk of suicide among men who were short at birth (less than 47 centimeters) persisted no matter what height they reached in adulthood, said the study authors, who looked at almost 320,000 Swedish men born between 1973 and 1980.

Short height in adulthood also boosted suicide risk. Men who were normal-length babies, but were short adults, were 56 percent more likely than taller men to attempt suicide. The taller a man was, the less likely he was to attempt suicide.

The researchers also found that men who were born underweight (less than 2,500 grams), but who reached normal height as adults, were more than 2.5 times as likely to attempt violent suicide. Men born prematurely (therefore short and underweight) were more than four times as likely to attempt violent suicide as men born between 38 and 40 weeks' gestation.

The brain chemical serotonin may be a factor in these findings, the study authors said. Serotonin is crucial to brain development and low levels are factors in impulsivity, aggression and suicidal behavior. Premature birth and other factors that restrict growth in the womb may affect serotonin levels.

The study was published recently in the Journal of Epidemiology and Community Health.

More information

Mental Health America has more about suicide.