The member for Euroa, who is expecting her second child, will step away at the November state election after eight years.

"With a little one at home and another on the way, it is time for me to seek a job that offers greater flexibility," she said in a statement.

"Serving my community as the first member for Euroa has been the honour of a lifetime.

"The greatest pleasure of this job has been the opportunity it has afforded me to meet everyday people doing extraordinary things."

Victorian Nationals leader Peter Walsh said Ms Ryan, 36, had been a "driving force for positive change for regional Victorians".

"Steph leaves this role, and her roles in the shadow cabinet, with a proud record of championing a better future for country people where it's needed most," he said.

In 2014, Ms Ryan became the first woman to hold a leadership position in the Victorian National Party and won her seat with almost 65 per cent of the vote.

She is married to former Labor City of Yarra Councillor Simon Huggins, with whom she has a daughter.

Opposition Leader Matthew Guy said he and Mr Walsh will redistribute Ms Ryan's shadow cabinet portfolios before parliament returns in early October.

He did not expect to lose her from his shadow cabinet less than five months out from the state election, cutting the number of women on the coalition frontbench from seven to six.

"We'll have to find candidates, particularly, who are younger, female. She represents a demographic that's so important," Mr Guy said.

The Liberals plan to run a candidate in Euroa to compete with whomever their junior coalition partner preselects to replace Ms Ryan.

"The admin has been talking about that today and they'll meet a little later in the week," he said.

Deputy Premier Jacinta Allan said more support is needed to ensure a work-life balance for working families.

"It doesn't matter what job you do, balancing your family and your work commitments is the number one challenge for every single employee and each family works through those issues in their own way," Ms Allan said.

"At the moment the system as we know it for some families isn't well-suited for them."

Australian Associated Press