There are concerns it'll take a death during child-birth for the Government to act on reinstating Lumsden's Birthing Unit.

Health Minister David Clark has rebuffed Clutha-Southland MP Hamish Walker's renewed push for services after a woman gave birth in an ambulance near town this weekend.

The expectant mother travelled from a farm about 30 minutes from Te Anau to Lumsden about 5am Sunday morning to meet her midwife, Sarah Stokes.

Once she arrived in Lumsden, it was quickly decided to send her to Invercargill because there was no oxygen supply in the town or any back-up for Stokes.

But about 20 minutes out of Lumsden, the baby boy was born on the side of the road.

It has been more than a month since the Lumsden Maternity Centre was downgraded as part of a region-wide overhaul of maternity services by the Southern District Health Board. Critics say the promised maternity services meant to replace the clinic have not been delivered.

Clark says the system of care worked appropriately because she had her midwife and the St John crew member.

He says more services are being delivered to more people in Clutha-Southland and Waitaki, and is asking whether Walker wants that rolled back.

"Indeed, should we return to the situation under the National Government where there were fewer services for those constituencies, I wish him well at the next election." 

Lumsden Maternity Centre director Carrie Adams says the decision to downgrade the maternity hub was based on inaccurate information in the first place.

She told Heather du Plessis-Allan they needed to rely on pregnancy numbers, rather than births for the area.

"Primary units are for your everything's going well pregnancy, and the reason why they are encouraged is because they are cheaper in the long run and the health outcomes are better for women who
birth there."