The UK is in the "relegation zone" when it comes to decently-paid maternity leave in Europe, an analysis by the Trades Union Congress (TUC) has found.
New mothers in Britain receive just six weeks of decently-paid entitlements on average, while most European countries offer three months or more.
The UK came 22nd out of 24 European countries that offer statutory maternity leave, with only the Republic of Ireland and Slovakia coming lower in the rankings.
Croatia offers the highest amounts of paid maternity leave at six months, with Poland, Hungary and the Czech Republic offering four months or more on average.
"The UK is in the relegation zone when it comes to decently-paid maternity leave," TUC general secretary Frances O'Grady said.
"Many Europeans countries offer decent support to new mums. But lots of parents here are forced back to work early to pay the bills.
"My advice to all new mums is to join a union. It is the best way to improve your pay and conditions."
The TUC called on the government to increase statutory maternity pay to the same level as the minimum wage so that mothers are not forced back to work before they are ready.
Decently-paid maternity leave is defined as two-thirds of women's pre-maternity leave earnings or more, or a rate of pay greater than £840 ($1,048) per month.
Most employed mothers are entitled to 52 weeks' maternity leave and 39 weeks' statutory maternity leave.
However, women who earn under £112 a week are not eligible for statutory maternity leave but may be entitled for maternity allowance. There are currently 1.4 million women in the UK earning less than this amount.
Ros Bragg, director of the charity Maternity Action, said: "Without adequate maternity pay, women's choices are limited and many cannot afford to take their leave entitlements.
"We should be investing in support for pregnant women and new families."