Louise Upston claimed during a meeting with midwives in Invercargill yesterday district health boards might be using the money provided for the 48 hours of care for mothers after giving birth, elsewhere.
She believed her Bill could put pressure on them to not use the money in other areas.
The Southern District Health Board was unable to respond to her claims by deadline.
MPs Ms Upston and Sarah Dowie hosted the talk about the 3 Day Postnatal Stay member's Bill.
During the conversation, Ms Upston said under the current regime, mothers were entitled to 48 hours of care, but in many circumstances, they were moved on well before 48 hours, leaving some mothers ''petrified'' to go home.
She said the most dangerous moment of a person's life was when they gave birth or when they were born.
''DHBs are funded to deliver this service. These first days are the most precious and mother and baby must have everything they need.''
The midwives at the meeting said the idea was good, but the main issue in the southern region was the lack of funding for midwives and the recent closure of the Lumsden maternity centre.
''I don't think it will make any difference your Bill, Louise. I'm sorry to tell you, because the DHB will say 'we can't do it','' retired midwife Anne Clarke said.
Winton Maternity Centre manager Debbie McDougall said the first question from mothers who arrived at her centre was ''when do I need to leave?''
She said the Bill would give a ''reassurance that no-one would be bumped out''.
