He and partner Julia Woods were delighted their baby daughter Eva Maree decided to arrive three days early – a gorgeous Father's Day gift.

Cradling all seven pounds and three ounces of his baby girl and watching her grasp his hand Mr Zwalf said he was ecstatic to become a father.

"It seemed entirely academic until we had five minutes to go in the birth," he said.

"I knew we were going to have a baby, there were people in here helping us have it and Julia's parents were eagerly waiting outside for Eva to come. It was just a beautiful moment – I nearly cried."

But the Queanbeyan couple said getting used to life as a trio would be a big adjustment. "We have to be grown-ups all of a sudden," Mr Zwalf joked.

Director of Family and Community Statistics at the ABS, Lisa Conolly, said while mothers still did most of the childcare new figures showed the number of dads using flexible working arrangements to care for their children has doubled since the mid-1990s.

"The number of dads working from home to care for their children doubled from 7 per cent to 14 per cent, while dads who worked part-time to care for their children rose from 1 per cent to 5 per cent," she said.

Mr Zwalf is among the 30 per cent of Australia's 5.4 million dads taking advantage of flexible work hours. He plans to pepper his work schedule with days off caring for his young bub.

"I will take four weeks of paternity leave and then come to some leave arrangement so I can be at home to help out one day a fortnight," he said.

Before Eva's arrival the couple had put together a home office so Mr Zwalf could balance nappy changes and feeds with his work as assistant national secretary of the Labor Party.

Ms Woods, who hopes to return to work as a fertility nurse, said Eva was already so content in her dad's arms.

She felt good knowing as their daughter grew she would have plenty of one-on-one time with her dad.

"I think he is going to be a fantastic father," she said. "I can tell already that she is going to be a daddy's girl completely."