When TV and radio star Kate Langbroek began to formulate plans for a much-wanted addition to her packed-to-the-rafters family, she had a home extension in mind - not another baby!

But her dreams of renovating her heritage-listed farmhouse in Melbourne's bayside suburbs to create space for her growing brood had barely left the architect's desk when Kate discovered her renovation budget would have to stretch to include a nursery. Baby number four was on its way!

Breaking the news
'I was like Cleopatra - stuck in denial,' Kate, 44, chuckles. She was already juggling the demands of three children under six with a 4.30am start for radio station Nova 100's breakfast show Hughesy & Kate when a home pregnancy test revealed the news.

'With Lewis, then five, just in school and our two youngest - Sunday, three, and Artie, almost two - still in nappies I was dreading telling my husband Peter,' Kate says. 'I was still in shock when I chased him around the house trying to show him the pregnancy test stick and yelling: "You've got to look at this!"

'But Peter was so thrilled and positive that it made me think some things are just meant to be. And once I'd got my head around it, I was excited too.'

Today, nursing slumbering son Jan Allan Langbroek Lewis in her arms, Kate and Peter couldn't be happier as they pile their older kids into one bedroom to make room for the new arrival.

'The first week home from hospital was a bit hectic,' Kate admits about the bub, who was born on July 17. 'But Jan - who is named after my Dutch dad Jan and Peter's grandpa Allan - is such a placid, easy baby. Even though it's going to be a bit squeezy for a while we manage pretty well.'

Kate and Peter are sharing the
workload at home after Jan's arrival

It's all worth it
Despite the sleepless nights and nappy changes, the popular former Dancing With The Stars contender adores being a mum.

Kate reveals the mayhem of being a mother of four caused a dramatic lifestyle change. Just seven years ago she lived the fast-paced life of a single girl and couldn't imagine anything else.

'I was never very maternal but that changed when Peter and I married and four months later had our son Lewis,' she says.

Eighteen months later they welcomed daughter Sunday. And 18 months after that, Kate gave birth to second son Artie.

'This is the biggest gap I've had so far, although I was pretty horrified when I realised I was pregnant... again!' she laughs.

'With Lewis in prep at the local primary school, and Sunday and Artie at the same playgroup, life had returned to normal and everything was sweet.'

Kate had even rejoined her local gym and resumed work at Nova when the pregnancy test threatened to plunge her back into a world of sleep deprivation.

'It was a bit embarrassing, telling my manager and worrying people would say I should know better,' she says.

Kate, husband Peter and the kids are
rapt to share their lives with baby Jan

An old hand
As with her previous pregnancies, which were dogged by morning sickness, Kate knew the nausea would subside by the 14th week.

'It was smooth sailing after that,' she says, playing down a rare pregnancy-related liver condition which can cause the placenta to break down. 'I worked up until three days before Jan was born.

'Considering I was getting up for work at 4.30am and caring for three children, including two in nappies, it went pretty well.'

Kate was convinced she was having a girl and performed every test under the sun to determine the sex of her fourth child. 'Everything but ask a medical professional, who could have told her the sex in two minutes!' laughs Peter, 34, an engineer.

Booked in two weeks before her due date for an epidural caesarean, Kate was 'terrified I'd see myself disembowelled'.

'And I got such a shock when doctors dangled Jan over the screen. I asked if it was a girl... and then I saw his meat and two veg and thought: "That's no girl!"'

Keeping a routine
Proud parents Kate and Peter say the other kids adore their brother. 'Jan looks just like Lewis, with his huge eyes, but he's got my dad's regal nose,' Kate adds.

The secret to her happy house, she reveals, is having a highly organised stay-at-home dad who takes care of breakfasts, dressing and feeding the three eldest, and the school run.

'After taking paternity leave with Artie, Peter wanted to leave his job and support my career,' Kate says. 'A week later he bought a bar and works there two days a week, which means one of us is always around for the kids.'

His morning shift allows Kate, who returns to radio duties this week, to catch up on some sleep after Jan's early morning feed.

'Jan's definitely our last baby - definitely,' Kate says, smiling as children gallop in and out of rooms she claims they've outgrown. 'The renovation can't happen quickly enough. We're like sardines!'