Becoming a dad before the age of 25 is linked to a heightened risk of dying early in middle age, indicates a sibling study published online in the Journal of Epidemiology & Community Health.
The published evidence suggests that men who father a child in early life have poorer health and die earlier than men who delay fatherhood, but family environment, early socioeconomic circumstances and genes are thought to explain this association.
In a bid to tease out the underlying factors, the researchers used a 10 per cent nationally representative sample of households drawn from the 1950 Finnish Census.
This involved more than 30,500 men born between 1940 and 1950, who became fathers by the age of 45. The dads were tracked from the age of 45 until death or age 54, using mortality data for 1985-2005.
Some 15% of this sample had fathered their first child by the age of 22; 29% at ages 22-24; 18% when they were 25-26;19% between the ages of 27and 29; and 19% between the ages of 30 and 44.
The average age at which a man became a dad was 25-26, and men in this age bracket were used as a reference.
The researchers took account of influential factors, such as educational attainment and region of residence, which are linked to the timing of first parenthood; and marital status and number of children, both of which are linked to long term health.
During the 10 year monitoring period around 1 in 20 of the dads died. The primary causes of death were ischaemic heart disease (21%) and diseases related to excess alcohol (16%).
Men who were dads by the time they were 22 had a 26% higher risk of death in mid-life than those who had fathered their first child when they were 25 or 26. Similarly, men who had their first child between the ages of 22 and 24 had a 14% higher risk of dying in middle age.
These findings were independent of factors in adulthood or year of birth.
At the other end of the scale, those who became dads between the ages of 30 and 44 had a 25% lower risk of death in middle age than those who fathered their first child at 25 or 26.
The risk of death for men fathering their first child between the ages of 27 and 29 was the same as that of men in the reference group.
In a subsidiary sample of 1124 siblings, brothers who had become dads by the age of 22 were 73% more likely to die early than their siblings who had fathered their first child at the age of 25 or 26. Similarly, those who entered parenthood at 22-24 were 63% more likely to die in mid life.
These findings were held true, irrespective of year of birth, shared early life circumstances, educational attainment, marital status, region of residence, and number of children.
Once again, men who became dads between the ages of 30 and 44 had a 22% lower risk of a mid-life death, although this was statistically the same as those who fathered their first child at 25/26.
"The findings of our study suggest that the association between young fatherhood and mid life mortality is likely to be causal," write the researchers.
"The association was not explained by unobserved early life characteristics shared by brothers or by certain adult characteristics known to be associated both with fertility timing and mortality," they explain.
They go on to say that although having a child as a young adult is thought to be less disruptive for a man than it is for a woman, taking on the combined role of father, partner and breadwinner may cause considerable psychological and economic stress for a young man and deprive him of the ability to invest in his own wellbeing.
The researchers point out that while these factors may not be so important for today's generation of dads, they may nevertheless experience other types of stressors.
"The findings of our study provide evidence of a need to support young fathers struggling with the demands of family life in order to promote good health behaviours and future health. The promotion of good health behaviours in young fathers could also support healthy behaviour in their children," they suggest.