Mr Walker, the National MP for Clutha-Southland, this week submitted written evidence in support of his 5000-signature petition protesting the downgrade proposal.
"There is huge community support for the centre, which is a vital health asset to rural Southland," Mr Walker said.
In March the Southern District Health Board unveiled its maternity plan, which included a range of changes to reorganise services across Otago and Southland.
The proposal to reduce LMC from a birthing centre to a "maternal and child hub"— offering ante and postnatal care, but used by birthing mothers only in case of emergency — has proven highly controversial, prompting locals to stage protest marches against the change.
Northern Southland Health Company, the charity which runs LMC, is still considering seeking a judicial review of the decision.
Mr Walker told the select committee that midwives or lead maternity carers’ ability to handle emergency situations would be jeopardised by the downgrade.
"Not all the adequate equipment will be on site, including medication to address emergency post-pregnancy situations," he said.
"On-call midwives will struggle to attend births or emergency situations in the Northern Southland area from their bases in Invercargill, Gore and Winton — it is some 130km from Winton to Te Anau, as the closest base if Lumsden is downgraded."
There had been multiple examples of mothers making it "in the nick of time" to Lumsden to give birth unexpectedly, and the change put the health and safety of babies and women at risk, he said.
"24/7 cover is not available in rural Northern Southland and with the struggles of first responders in all of Southland the risk is even higher now for expectant mothers than ever before."
The health select committee is still considering Mr Walker’s petition, and he may be asked to make further submissions.
