Jools Oliver shows off her bump as she and Jamie share their joy at baby No.3

Pregnant Jools Oliver stepped out yesterday for the first time since it was revealed that she and TV chef husband Jamie are expecting their third child.

The 34-year-old former model's bump was clearly visible as she headed for the couple's North London home with their two children.

Earlier a spokesman said: 'Jools is expecting the couple's third child in April. The Olivers are delighted and excited about the news.'

Thrilled: Jools Oliver, who has announced she is pregnant, shows her baby bump off as she picks up her daughters from school in London

A friend said Jamie, 33, and Jools have asked not to be told whether it is a boy or a girl. 'They want a surprise,' the pal added.

Earlier this year, Jools revealed that she was prepared to undergo further gruelling fertility treatment to conceive, because the TV chef was desperate for a son.

The former model underwent months of hormone treatment to have the couple's daughters Poppy Honey, six, and Daisy Boo, five.

Happy family: Jamie Oliver, wife Jools and children Daisy Boo & Poppy Honey attend The Queen's 80th birthday at Buckingham Palace last year

A source close to the star insisted that the latest addition had been conceived naturally.

The source added: 'They don't mind what sex it is. Jamie would prefer a boy if pushed but whatever appears in April, they will be delighted.'

Mrs Oliver – born Juliette Norton - has been the model wife while her husband has pursued a high-profile career on television.

Last month she said: 'I would love more kids but number three is taking much longer than I thought. If I have to go through the fertility drugs again, I will. Jamie would do anything to have a boy.'

High hopes: Jamie and Jools seen shopping near their North London home a few days ago. The couple are hoping for a boy this time

Jools has published a non-fiction book about her problems conceiving. Minus Nine to One: The Diary of an Honest Mum, famously revealed intimate details of the couple's fertility process, including one about Jamie racing across London on his scooter to deliver a jam jar of his sperm to Hammersmith Hospital.

The couple have been married for eight years, during which Jamie has seen his profile soar.

He made his name on BBC2 as the Naked Chef but was poached by Channel 4 in a six-figure deal.

The star also founded the restaurant chain, 15, to train disadvantaged young people.

In recent years he has campaigned on public health issues, notably Jamie's School Dinners which campaigned for the provision of better quality meals for school children.

This year he also criticised the plight of battery farm chickens, even slamming paymasters Sainsbury's for not taking part in a debate about the issue.

The 32-year-old is paid £1.2million to front the supermarket's advertising campaign.

His latest scheme for Channel 4, called Ministry of Food, sees him try to teach the nation how to cook well from scratch.

Despite repeated rumours that their relationship has suffered because of his work commitments, the couple insist they are happier than ever.

Mrs Oliver has said: 'It sound old-fashioned but I think, when you're with someone like Jamie, you need a wife like me.

'I'm in the background, making sure the kids are in bed and everyone's happy. There is nothing I would rather do.'

'Even if I imagine going out with other men, Jamie has got more of what I want. If they were better looking, taller, hunkier, I would still think that Jamie's better.

'He is calm, he is not a worrier, nothing is a problem. All my friends like him, and he is a man's man. He never gives me any worries.'