The Federal Opposition says Coalition frontbencher Kelly O'Dwyer's decision to quit politics highlights the Liberal Party's failure to promote and support women in its ranks.

Key points: Bill Shorten argues Ms O'Dwyer's departure further emphasises the problem the Liberal Party has in attracting and retaining women

Bill Shorten argues Ms O'Dwyer's departure further emphasises the problem the Liberal Party has in attracting and retaining women Labor has put in place quotas to ensure half of its parliamentary members are women

Labor has put in place quotas to ensure half of its parliamentary members are women Women in the Liberal party are frustrated another of their colleagues is leaving politics

The Minister for Jobs and Women made the shock announcement at the weekend, saying she wanted to spend more time with her young family and give herself the best chance of being able to have a third child.

She revealed in News Corp papers she had suffered a miscarriage while in Parliament and away from her family.

Politicians from across the divide said on Sunday they respected Ms O'Dwyer's decision to prioritise her family over her political career.

Opposition Leader Bill Shorten argued her departure emphasised the problem the Liberal Party has in attracting and retaining women.

"The big point about her going is that she is the only Liberal woman, just about, in the Victorian Liberal Party in the House of Reps," Mr Shorten said.

"It's not her going which is the issue, that's her business. It's the fact that once she goes, what other women are they going to put on the frontbench?"

Labor MP Kate Ellis, who is also leaving Parliament to spend more time with her family, said she had been surprised by Ms O'Dwyer's announcement.

"I think lots of people were surprised, but also I understand," Ms Ellis said.

"You can be a great parent and a great member of Parliament.

"It just wasn't what's best for me and obviously Kelly's decided it's not what's best in her circumstances either."

Labor has put in place quotas to ensure half of its parliamentary members are women.

It is an approach criticised by members of the Liberal Party in the past as putting gender before merit in picking candidates.

Prime Minister Scott Morrison denied his party had a poor reputation when it came to female representation, but suggested the way his party picked candidates would always be under review.

"The selection process for this year's election still has a little way to go, but that processes were set in place by my predecessors in the party, and they're run by the party," Mr Morrison said.

"But those matters are ones that I would intend to return to as leader of the party after the next election, and to deal with that and put in place long-term plans to make sure we meet the commitments that we have set out as a party, working closely with the party organisation."

Woman wanted to replace O'Dwyer

Sorry, this video has expired Kelly O'Dwyer retires from Parliament citing personal reasons

Women in the Liberal party are frustrated another of their colleagues is leaving politics. They are concerned not only about the strains of the job, but also the damage it does to the Government's brand.

Some are also worried it will not be the last departure announced before the election.

Ms O'Dwyer said she wanted a woman to replace her as the party's candidate for the inner-Melbourne electorate of Higgins.

Mr Morrison agreed and suggested he was "very confident about a very strong female field" of candidates emerging in coming days.

Liberal Senator Jane Hume had been considering seeking preselection in the seat but said she had decided against it.

"I understand it's my home seat and of course I thought about it over the weekend but I just love my role in the Senate and particularly those of deputy whip and chair of the Economics Legislation Committee," she said.

"I realise the party has given me an extraordinary privilege by endorsing me for the next six years and I am very reluctant to leave the good work that I am doing there."

Senator Hume said she hoped the Liberal Party would choose a female candidate to contest the seat.

"I do believe that it would be terrific to get a good, high-calibre woman into the seat of Higgins because that's what the people of Higgins deserve, that's what the Coalition needs to win the next election, we need far more women in all states and in all seats," she said.

"We actually now have a chance to bring in fresh talent to the team and really add weapons to the arsenal to fight the next election."

Katie Allan, who unsuccessfully ran for the Liberals in the state seat of Prahran, might now put her hand up.

Former Liberal senator Judith Troeth said it was incumbent on local preselectors to choose a woman.

"I have seen many, many preselections where men of lesser merit were chosen over women of much greater merit," she said.

"This is the ideal time to get a professional, talented woman into a safe seat at the moment, which would give her the opportunity to have a long career in Parliament and the opportunity to establish a ministerial career."

Coalition frontbenchers defend O'Dwyer

Coalition frontbenchers were quick to defend Ms O'Dwyer's decision to quit politics, suggesting any claim she was jumping ship before the Government faced a tough election were wrong.

"I think people would be very unfair to Kelly if they interpreted it that way," Nationals Minister Darren Chester said.

"She indicated that, obviously, as a young family — and they want to extend their family — she had had some difficulties in having children in the first place."

The Prime Minister said Ms O'Dwyer's motives should not be questioned.

"I think we should be careful about how we characterise these decisions, they're deeply personal decisions," Mr Morrison said.

Speculation is rife as to how many other Government members and senators will announce their departures before the election is officially called.

The unofficial election campaign is already underway, with both major parties making policy announcements on Sunday.

The Coalition rolled out $96 million dollars to subsidise lung cancer medication, while Labor pledged $46 million for kids swimming classes across the country.