Men who have children earn almost a fifth more than their childless counterparts by the age of 40, according to a think-tank study.
The IPPR said the “fatherhood pay bonus” had increased over recent decades but that women who gave birth at an early age were tending to end up worse off than before.
Researchers compared the fortunes of men and women born in 1958 and 1970 as part of a project to assess the impact of feminism on working life in the UK.
They found the younger cohort of mothers suffered less of an earnings differential than their own mothers’ generation by the time they reached 40 – 11 pc down instead of 14 pc.
There was also less of a gap between their pay and that of fathers the same age – the so-called “motherhood pay penalty”.
But the think-tank said it had been surprised to discover the extra earnings fatherhood appeared to help generate – 16pc more for those born in 1958 and 19pc for the 1970 generation.
Potential explanations were that the incentive of being breadwinner for a family pushed them to work harder, that employers rewarded their perceived increased loyalty or that men tend to wait until they have a decent wage to have children.
The women born in 1970 who had children by the time they were 24 were likely to earn 20pc less than those without children – a rise on the previous 17pc. For those who gave birth later the gap shrank from 12pc to 10pc.