A study found that married men have lower levels of testosterone than those who remain single, and the stress of being a father may be to blame.

• The researchers say the data may reflect “the stressors of family life, including children”.

Men have long blamed their children for lowering their bank balances, but not yet their testosterone levels.

However, research has found that married men have lower levels of testosterone on average than those who remain single, and the stress of having a family could be responsible.

An analysis of 11 scientific studies involving more than 25,000 men found that those who are married or in a relationship have lower testosterone levels.

Interestingly, this was particularly the case in studies of middle-aged men, and less so in older men.

“This may reflect the stresses of family life, including the children in the family,” say the researchers who conducted the analysis.

There is evidence from previous research that exposure to stress can reduce the amount of testosterone that men produce.

But this is just one possible explanation, as the analysis was not designed to determine whether parents could blame their children for low testosterone.

It is not clear how much the modest decrease in testosterone in married men, who still have a normal amount of the hormone, affects them.

However, it was previously found that men with abnormally low testosterone have lower sex drive and experience more fatigue.

“An interesting finding is that married men, or men in an active relationship, have slightly lower testosterone levels than single men,” said Dr Bo Yip of the University of Western Australia, who led the analysis.

“A possible explanation could be that married men with families may be more stressed and therefore have lower testosterone levels, but our study was not designed to look further at this finding.”

There has been more focus in recent years on “male menopause” – where men’s testosterone levels decline as they age.

The new analysis, published in the journal Annals of Internal Medicine, found no significant difference in average testosterone concentrations in men ages 17 to 70.

But after the men reached the age of 70, their testosterone levels, on average, dropped.

The researchers set out to look at lifestyle factors, such as being married or single, that might affect testosterone in addition to age.

They also found that men who did no more than 75 minutes of vigorous physical activity per week had lower testosterone than more active men, on average.

Testosterone levels were also lower in the heavier men, based on body mass index (BMI).

Low testosterone concentrations have previously been linked to an increased risk of diabetes and dementia, and an increased risk of premature death.

It also found that testosterone concentrations were slightly lower in men who were former smokers, compared to men who had never smoked, and in those with high blood pressure and those with a history of certain health conditions including cardiovascular disease.

The authors say these factors must be considered before men can be told they have abnormally low testosterone.

Previous evidence has shown that men notice a drop in their testosterone level when they are expecting a baby, and men whose testosterone drops the most are more interested in their children and feel more satisfied with being fathers.