Ms Warren said she was disappointed at the sort of questioning new Labour leader Jacinda Ardern had faced, but was proud of the way Ms Ardern had responded.
On a TV show just hours after her leadership appointment, Ms Ardern was asked if she would be making the choice to have children.
And Mark Richardson pushed her further about her parenting plans on his radio show, prompting Ms Ardern to say it was an inappropriate question for women.
"It is unacceptable in 2017 to say that women should have to answer that question in the workplace. It is the woman's decision about when they choose to have children."
Ms Warren said her pregnancy has been "rough" with bouts of morning sickness and then she contracted whooping cough.
"I am tired and I am spending quite a bit of time either sleeping or expressing milk," she said.
Her baby is being cared for in the neo-natal unit at Whanganui Hospital and Ms Warren said she and her husband take turns to be there to tube-feed the infant.
"He will be there for the feeding while I'm door knocking in Feilding on Sunday.
"It has never occurred to me that I might withdraw my candidacy - I have a good husband and a great support network of family and friends."
Her parents live in Kai Iwi and are helping out.
"Dad cooks huge meals for me and mum has been doing all the washing."
Her baby was doing well, she said.
Ms Warren has experienced a boost with the appointment of Ms Ardern as party leader, with 39 new volunteers offering support.
Rangitikei has been a safe National seat since the 1930s and Ms Warren is up against incumbent Ian McKelvie.
