This will be Lucy's first TV project since having her second baby Holly last April. She also has a son Jack (3) who was born in November 2009.
The hour-long pilot -- which is being made by production company Adare -- follows two sets of parents in one house over the course of a week and will be presented by Lucy.
Adare previously worked with Lucy on her celebrity-led show Livin' With Lucy which saw her moving in with a host of personalities including the late Jade Goody and Calum Best.
The brave families taking part in the show will have their every move captured by no less than 13 robotic cameras erected in their homes to film their parenting techniques.
Speaking about the use of the robotic cameras, producer Brian Graham described it as a "new and brave departure" for the station.
"It's the first real 'rig show' of its type in this country.
"It was a very complicated production, in effect turning a real house into a set where all areas were covered for sound and vision, the gallery was constructed in the adjacent house.
"It's a strong format, right up RTE Two's street -- young, edgy and relevant," he said.
Keeping Mum is part of a new format project commissioned by RTE as it looks to develop new programmes. Entitled the Format Farm, it was behind last summer's pilot of The Hit and The Love Clinic.
The show will mark a welcome return of bubbly TV presenter Lucy, who has spent the past few months trying to shift her baby weight.
She got help from the Hospital Group after signing up to their 'made to measure' HCG diet, which helped her drop nearly a stone in a month.
Lucy admitted that there's definitely extra pressure on well-known Irish women to get their shape back shortly after becoming mums.
"While having a baby is the most amazing thing in the world, when you're out at events and on the telly, you do feel a little bit uncomfortable.
"I was on the red carpet at Colin Farrell's movie premiere, very casually trying to adjust my Spanx -- whereas now I don't have to wear them," she laughed.
"It's so nice just to be able to wear nice clothes and feel like me again."
Lucy, who has been married to Richie Governey for the past four years, previously fronted a 2fm breakfast show with Baz Ashmawy.