Currently, rules allow pregnant women 14 weeks on full pay. In the UK, pregnant women are entitled to a year off work, with the first six weeks on 90% of their salary, followed by 33 weeks on Statutory Maternity Pay. The rest of the period is unpaid.
The new legislation has led to concerns that, if the legislation is passed, companies will discriminate against women of childbearing age. A number of prominent business groups have also criticised the proposed legislation, claiming that the increased outlay for employers will impact negatively on the UK's businesses and the wider economy.
Adam Marshall, director of policy at the British Chambers of Commerce (BCC), said: "The Pregnant Workers Directive should be about setting minimum EU standards for the health and safety of pregnant workers - not adding new payroll costs for overburdened companies and national social security systems.
"This vote introduces complexity and uncertainty, which are totally unnecessary, as the UK and other EU countries already have well-developed national maternity pay systems.
"Companies need to be given the space to deliver growth and jobs - without being hamstrung by new and costly maternity rules.
"As the Directive moves forward, we urge the European Parliament as a whole and the council to overturn these costly amendments."
And Sarah Jackson, chief executive of Working Families, added: "Yesterday's vote in favour of 20 weeks of maternity pay on full pay from Brussels is an ambition that we would endorse. Evidence shows that finances dictate when low paid women return to work. Apart from the first six weeks, the UK pays women less than the national minimum wage in SMP. This sends a poor message about the best start in life for low income families.
"The idea that this would have an impact on employability should be knocked on the head: in the UK the state - not the employer - pays SMP. We're also pleased to hear EU talking about paternity pay - over 40% of fathers don't take any paternity leave at all, the majority because they can't afford it and this needs addressing urgently."