A fifth of fathers had no entitlement to parental leave, according to research by charity Working Families.
Its Working families index, which surveyed more than 3,000 working parents, also found that two-fifths of mothers could not take the time they needed after the birth of their child, while 14% were not entitled to parental leave.
Where enhanced parental leave was available, fathers took three and a half weeks more than those without, while mothers took an average of six additional weeks.
Mothers concerned about finances returned to work eight weeks earlier than those without money worries, with 47% of parents saying they could not afford to take more time off. Approximately 70% of fathers who did not take their full two weeks of statutory paternity leave cited money worries as the reason.
Almost two-fifths of families have gone into debt and over a third have used their savings to cover childcare costs. Two-fifths said cost prevents them from using as much formal childcare they would like, and two-thirds said accessing the childcare they need puts a strain on their finances.
Less than half (45%) said they can easily access the formal childcare they need, and 87% would carefully consider childcare options before applying for a promotion or a new job.
Two-fifths of parents and more than half of solo- and co-parents said finding childcare has negatively influenced their mental health, and a third have reduced their working hours to manage childcare.
Jane van Zyl, chief executive officer of Working Families, said: “The UK’s approach to parental leave is putting new parents under immense financial pressures. Families are being forced to make impossible choices at the most critical time, often returning to work before they’re ready, simply because they can’t afford not to.
“The findings add to growing calls for stronger parental leave rights and better financial support for families in the early months of a child’s life. Working Families is urging employers to offer enhanced parental leave and for policymakers to review statutory provision so all families have a fair chance to care for their children without financial penalty.”