Trade and Industry Secretary Patricia Hewitt has ordered a national inquiry after a new mother was sent her P45 together with a congratulations card from her employer.
Carol Bonehill, from Birmingham, won nearly £9,000 compensation for sexual discrimination and unfair dismissal after taking her case to an industrial tribunal.
Ms Hewitt asked the Equal Opportunities Commission to investigate the extent of discrimination against working women who have children.
She called Ms Bonehill's employers, P H Adams Electrical Contractors Ltd, a "disgrace" and said such actions were "Victorian management practice".
Ms Bonehill said she had received the envelope containing notice of her
dismissal the day after she rang her Erdington-based employer with news of the birth of her daughter Abbie.
It is depressing that something as natural as childbirth is still seen as an
alien and unwelcome concept by some employers
Trade and Industry Secretary Patricia Hewitt
The 29-year-old, who has a partner and seven-year-old daughter, said: "I was sacked for having a baby.
"I was so shocked and upset to receive the letter - it was totally out of the blue."
Bosses at the firm, who were ordered to pay £8,835 compensation, maintain Ms
Bonehill, who was a receptionist, was not sacked because she was pregnant but
because of a poor attendance record.
Director Russell Norton said: "There was no way we sacked Carol because she was pregnant.
"Carol was dismissed due to extremely poor attendance during her
four months with us."
'Simplify maternity leave'
He added: "Our big mistake was the letter, which went in the same envelope as the congratulations card.
"It was a total mistake and we have apologised."
But Ms Hewitt said the case was a "woeful example of Victorian management practice".
"We have recently changed the law to simplify maternity and paternity leave
for parents and to make it easier for firms to help employees balance work and
family life," she said.
"It is depressing that something as natural as childbirth is still seen as an
alien and unwelcome concept by some employers.
"A small minority are continuing to give the majority a bad name and seem
determined to break the rules.
"That is why I have asked the Equal Opportunity Commission to look into this
issue and see what more can be done to introduce employers like this to the
facts of life in the 21st Century."