A new members' bill would allow employees to take up to three days bereavement leave after losing a pregnancy in a miscarriage.

The bill, in the name of Labour MP Ginny Andersen, would make miscarriage an explicit grounds for three days of bereavement leave.

Currently the law is somewhat ambiguous on the issue, with employers being able to decide whether or not a miscarriage constitutes bereavement.

Maarten Holl/Stuff Labour's Ginny Andersen.

"It's unclear whether an unborn child is classified as a child," Andersen said.

It would apply to both the mother and the father.

"One pregnancy out of four can end in a miscarriage so it affects a lot of women and their partners," Andersen said.

"It's important that women and their families have time to grieve and deal with not only the physical but the emotional strain of going through miscarriage."

The law was drafted after a group of women who felt they had had "quite poor treatment" from their workplaces after having miscarriages visited Labour's Clare Curran.

"I worked with the group of women to understand what their experiences were and drafted the bill."

Andersen planned to speak to MPs from all parties in an attempt to get bipartisan support for the bill.

Another leave-related members' bill was passed without support from National or ACT in recent weeks - Jan Logie's domestic violence leave law.

National supported the bill in early stages but decided it would place too much of a burden on small employers prior to it passing.