Despite being more free to reveal their pregnancy, as many as 42% said they felt uncomfortable about admitting they were unwell.

And the survey of 3,000 first-time pregnant women found that 37% thought having a baby meant they would be passed over for promotion and pay rises.

Of these 23% had put off having children for fear of the impact it would have on their career.

But more than 60% found their colleagues were more supportive during their pregnancy.

Financial problems

The main worries of mothers-to-be were money and fears that their relationship with their partner would change after the baby was born.

More than a third said they had delayed having a baby because of financial problems and over a half were worried that having children would harm their relationship.

Increased equality between the sexes was reflected by the fact that 55% thought financial responsibility for the baby was equally shared.

Psychologist Dr Maureen Marks said the results showed men's role as breadwinner was changing and they were taking a closer interest in their children.

Pregnant women feel under pressure at work

"Children will surely gain from having fathers who want to be involved with them," she said.

But she foresaw some problems, for example, with mothers and fathers competing with each other over who was the best child carer.

The survey found that many men took a keen interest in the pregnancy, with 44% of women saying their partner knew the same or more than them about having a baby.

And 71% felt their partner would happily forego football and the pub for an evening at the ante-natal clinic.

But the down side was that one in 20 women said their partners were jealous of the attention they got from others during pregnancy.

Mistaken sex fear

The survey also found that 40% of the pregnant women said they still had sex at least once a week.

But many admitted they had less sex than they would like, mainly because of a mistaken fear that it would harm the baby.

And 44% said they thought they missed sex as much as their partner and 13% reckoned they suffered more.

"Despite knowing about safety of sex during pregnancy, they still have unconscious fears and feelings around the mystery of pregnancy and about sex when there is a baby inside the woman," said Dr Marks.

The survey, carried out by Johson & Johnson, also found that 44% of women felt confused about dietary advice offered during pregnancy.

Many blamed the media for making them feel guilty they were not doing the right thing.

"This report highlights the danger that women's wish to do their best for their baby can so easily turn into them thinking they have to be 'perfect' to be good enough mothers, so much so that they no longer look after their own needs," said Dr Marks.

The survey also shows:

• Many women worried about conceiving, although 28% fell pregnant almost immediately
• A third of women became closer to mothers or mothers-in-law in pregnancy
• 40% said they had never been offered a seat on public transport