New Zealand endured day four of a four-week lockdown on Sunday, a nationwide clamp on business and movement of people designed to eliminate the spread of COVID-19 among Kiwis.

As part of the lockdown, hospitals are maintaining strict access rules on their wards, with mothers denied some support during childbirth, and afterwards.

Ms Ardern, who gave birth to her first daughter in June 2018, said hearing of the experiences of mothers was pulling at her heartstrings.

"I have such empathy. I have read the stories," she said.

"It wasn't so long ago that I was in that same position.

"But I've also read the stories of people who have loved ones who are very ill in hospital and are unable to visit as well.

"I recognise the need to keep mum and baby safe. It's what hospitals are needing to juggle at this incredibly difficult time.

"This is a devastating time I hope no New Zealander will ever have to experience again in the future and these are some of the devastating consequences."

Ms Ardern said she was also concerned mothers who had recently taken newborns home were missing out.

"I worry about that group," she said.

"They usually get visits and they usually get extra contact and they usually have extra support.

"And so for that group I just ask people within their wider circle stay in contact, reach out and check in on those families."

Australian Associated Press