Short male babies run more than double the risk of a violent suicide attempt as an adult, suggests a study in the Journal of Epidemiology and Community Health.
Catch up growth during childhood does not lessen the impact of short stature at birth, the research shows.
The findings are based on almost 320,000 Swedish men out of a total of more than 713,000 people all born between 1973 and 1980.
Using national registers, they were tracked from birth to the date of attempted suicide, death, emigration, or the end of 1999, whichever came first.
Short babies of less than 47 cm in length, were more likely to attempt suicide as adults, no matter what height they reached in adulthood, compared with normal length babies.
Short birth length also more than doubled the risk of a violent suicide attempt as opposed to a non-violent one.
A violent suicide attempt was defined as hanging, the use of a firearm or knives, jumping from a height or in front of vehicles, and drowning.
Short stature in adulthood also boosted the risk.
Men who were normal length babies, but who were short in adult life were 56% more likely than tall men to attempt to take their own lives.
The taller a man was, the less likely he was to attempt suicide, the findings showed.
Men who were born underweight (under 2500 g), but who reached normal height were more than 2.5 times as likely to make a violent suicide attempt.
And those who were born prematurely, and therefore short and underweight, were more than four times as likely to attempt violent suicide as those born after 38 to 40 weeks of pregnancy.
The authors suggest that the brain chemical serotonin may be key. It is crucial to brain development and low levels are important in impulsivity, aggression, and suicidal behaviour.
Serotonin levels may be affected by premature birth and other factors restricting growth in the womb, they add.
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