"Maternity leave does not break continuity of service with an employer. An employee on statutory maternity leave is still in the service of the employer, " said Ciara McLoughlin, a solicitor specialising in employment law with A&L Goodbody. "By way of example, where a male and female employee both commence work in year one and by year three the female worker has had three children and taken 18 months maternity leave (six months for each child), they will both have three year's service. Where an employer's pay scheme is based on length of service, both the male and female in this example must be given equal scoring."

Last week, the European Court of Justice ruled in favour of a female employee of the UK Health and Safety Executive, Bernadette Cadman, who claimed she was paid up to 13,000 less per year than four of her male colleagues who had longer service. Her employer defended the pay difference on the basis that the other employees had worked there for a longer period. The European Court upheld a lower court ruling that rejected the complaint.

However, some subsequent media coverage was misleading and may leave the impression that employers were free to take into account time off to have children when conducting pay reviews. There was a distinction between maternity leave and employees taking career breaks to care for children, McLoughlin warned.

The decision was met with dismay among some unions and women's groups, but Ms Cadman's own union, Prospect, said that the decision enshrined in law the right of employees to challenge pay inequality where length of service was unreasonably taken into account.