Image copyright Thinkstock Image caption Never touch a woman's bump, unless you have their permission, advise researchers

When Tanya, then pregnant, and her mother Diane, had lunch together in a cafe near their home in south Wales, they did not expect the waiter to tell them what they could eat.

But according to Tanya, he acted "like the kind of food police".

"He said 'The only things you can have are, um, cheese and pickle'."

Tanya's experience is typical of a generation of mothers who "feel watched and judged", suggests a Cardiff University study.

Diane told the researchers that the waiter was "adamant" that he would not serve them other types of food.

"It was just like, 'We can't serve you this.' It was like he was the pregnancy expert wasn't it?"

The Cardiff University team interviewed a small group of mothers and grandmothers in great detail for the study.

They were from a disadvantaged area of south Wales and found that the young mothers felt significantly more scrutinised by family, friends and strangers than the previous generation.

Tanya told the researchers that in another cafe, a man cleaning the floor had reacted to her getting out a bottle of expressed milk by asking her if she was breastfeeding.

She simply replied: "Yes", but later told researchers: "It's quite intrusive... I wouldn't walk up to him and say 'What did you have for your lunch today?'"

Another time a relative who found out that Tanya was planning to leave her baby with her mother when she went out, exclaimed: "Oh, she can't go out; she's breastfeeding. She can't drink alcohol."

Tanya was particularly offended as she had previously spoken to her health visitor about how to breastfeed her baby safely and drink alcohol on a night out.

She says that if she did attempt to breastfeed outside the home, people's stares often made her feel as if she was pole-dancing.

She resorted to expressing milk or hiding under a shawl.

By contrast, Tanya's mother Diane told the researchers that she had not experienced anything like the same pressure to breastfeed or eat certain foods when she was a young mother.

"When I was pregnant no-one cared.

"You could say, 'Oh I'll have a double vodka and Coke with my fag,' and it was like, 'Yeah no problem.'"

However, despite not having breastfed herself, Diane admitted having put her daughter under pressure to do so.

Lead researcher Dr Aimee Grant said the mothers in the study reported that "intrusive policing of lifestyle choices began in pregnancy and then continued to impact on their everyday lives, particularly through infant feeding".

"This observation and interference by others can result in pregnant women and new mothers performing public motherhood in ways that are highly self-aware and self-conscious, which makes it difficult to follow advice from health professionals."

Mothers often felt that they or at least their bumps were "everyone's property", the study found.

To avoid making pregnant women and young mothers feel uncomfortable, Dr Grant advises family, friends and strangers:

not to touch a woman's bump unless she has given them permission

and "if you wouldn't ask someone what they had for lunch, it probably isn't appropriate for you to ask them about feeding their baby".

The study is published in the journal Families, Relationships and Society.

The children were aged between six weeks and two years, the mothers between the ages of 22 and 43, and the grandmothers between 43 and 74.

Some names have been changed.