One of the women, Heather Crees, who worked for a large insurance company, yesterday told how she suffered from post-natal depression and had delayed her return in order to care for her premature baby who was suffering from severe medical problems.
Government figures show that thousands of mothers - around one in 20 - are unable to start back at work on time either because they are sick themselves or their babies need extra care.
The Royal London Mutual Insurance Society and Kwiksave Stores, the two employers concerned, were, however, given leave to appeal to the House of Lords so that the law could be "clarified".
The Court of Appeal yesterday decided that Janet Greaves, 36, who was employed as an assistant supermarket manager at Kwiksave and Mrs Crees, 42, formerly a clerk at Royal London had been unfairly dismissed.
Mrs Crees lost her home partly as a consequence of her dismissal and now lives in a caravan. She said her husband was forced to leave work to look after her and their son.
Mrs Crees, of Clacton, Essex, was sacked after sending a note explaining her illness to her employers. Mrs Greaves of Giles Gate, Durham, was dismissed after returning to work and handing in her explanation personally. Both companies claim that under employment law, the women had sacked themselves because they had not been "ready for work" on the first day after their maternity leave.
A spokeswoman for the Maternity Alliance said post-natal depression was a major problem for women and the Court of Appeal decision would have a significant impact. "We have to tell hundreds of women who call us every month to drag themselves into or risk losing their job."
Giving the ruling, Lord Justice Mummery, concluded that Parliament never intended that a scheme to protect female workers would allow companies to "take advantage of the temporary illness of a female employee to deny her the statutory right to return to work". Such an interpretation by employers would be "absurd and unjust".
He said the laws were "complex" and tried to strike a balance between protection of women at a time when they were "physically and emotionally vulnerable" and the business of an employer.
Urging the court to give leave for appeal to the Law Lords, Elizabeth Slade QC, representing the insurance company, said it was of "extreme importance" that the law should be clarified.
The MSF white-collar union and Usdaw, the shopworkers' union, which backed the two women's case, last night expressed confidence that the Law Lords would endorse the decision of the Court of Appeal.
John Monks, TUC general secretary, said the victory had great significance for all women workers who were treated unfairly when they became pregnant.Reuse content