We can be mums and MPs: O'Dwyer

Breastfeeding mum Kelly O'Dwyer wants women to know they can be mothers and parliamentarians at the same time.

It's also a none-too-subtle message to some of her male Liberal colleagues, especially those in the government whip's office.

The up-and-coming MP, tipped for promotion in Malcolm Turnbull's ministry, has been told to express more breastmilk so she doesn't miss votes in parliament.

The advice reportedly came from the office of Chief Whip Scott Buchholz.

Ms O'Dwyer won't publicly confirm the instruction, other than to say parliamentary rules allow breastfeeding mothers a proxy vote.

"The message I send to women is you can do both jobs - you can be a nursing mum and you can be a very good member of parliament," she told reporters on Thursday.

The parliamentary secretary returned to work after the winter break after giving birth to daughter Olivia in May.

Opposition Leader Bill Shorten couldn't believe what happened to Ms O'Dwyer, especially as the government has plenty of votes up its sleeve in the lower house.

"This seems to me some bloke trying to tell a woman colleague what to do and when to do it and how to do it," he told Network Ten.

"I just think it's ridiculous."

Opposition health spokeswoman Catherine King, who campaigned for the proxy vote after the birth of her son seven years ago, was equally perplexed.

"Proxy rule means you just inform whips office you are breastfeeding and vote still counted," she tweeted.

ACT Liberal Giulia Jones made history in August by breastfeeding her son Maximus in parliament during question time.

The ACT Legislative Assembly changed its rules after a Victorian politician was thrown out of state parliament for breastfeeding in 2003.