Statutory paternity leave should be twice as long and paid at almost twice the present rate to encourage more fathers to spend time with newborns, a think-tank said..
Under a blueprint drawn up by the Institute for Public Policy Research (IPPR) , fathers would automatically qualify for four weeks' leave after the birth, paid at the minimum wage.
The IPPR said one of the main reasons only 55% presently took off the available fortnight was because they felt they could not afford the loss of pay.
Under existing rules they qualify for a statutory £138.18 a week, equivalent to £3.45 an hour for a 40-hour week, with employers encouraged to make up the gap in the employee's usual pay.
Bringing the taxpayer-funded contribution up to minimum wage level would increase take-up to around 70%, the think-tank estimates, at a cost to the Treasury of around £150 million in 2015/16. It also called for the number of antenatal appointments fathers will be allowed paid time off to attend from October be doubled to four.
Senior research fellow Kayte Lawton said: " New parents need time away from work to care for their young children, and to strengthen their relationship with each other at what can be a hugely enjoyable but also very stressful time.
"However, this is often difficult for fathers because they have limited entitlements to paid leave, and so they often assume the role of breadwinner while their partner is on maternity leave.
"Fathers who take more than a few days off around the birth of their child are more likely to be actively involved in raising their child than those who do not.
"Fathers' greater involvement in family life can make it easier for mothers to return to work after taking maternity leave, which helps to raise the family's income and lessen the impact of motherhood on women's careers."