MPs should be given "baby leave", which would allow them to nominate colleagues to cast House of Commons votes on their behalf while they are caring for their child, Harriet Harman has said.
The former Labour deputy leader said MPs should also get six months' paid leave, in line with the Civil Service, and be able to nominate a full-time paid "maternity cover" representative for their work outside the Commons.
Ms Harman pointed out that 17 babies had been born to women MPs since 2010 and they had not benefited from a system of leave.
She has submitted her proposals to the Speaker's Commons Reference Group on Representation and Inclusion, which meets next week.
Before a speech to women from across the north of England at a Labour event in Newcastle, Ms Harman said: "Women have babies - that is a fact of life.
"Women are in Parliament - that's a democratic imperative.
"The baby needs time with the mother, the mother needs time with the baby and the constituency needs to be properly represented at all times.
"We need a proper system of baby leave to square that circle. It's long overdue."
She added: "The reality is you cannot be on call for your constituency or voting when you are in labour.
"And you should not have to be on duty when your baby is only a few weeks/months old.
"But the constituency must have a representative at all times. There needs to be a proper system of leave and cover.
"At the same time as the number of women in Parliament has increased, the expectations of fatherhood have changed.
"We have long argued that fathers need the opportunity to spend time with their newborn baby.
"Yet the parliamentary system itself makes no acknowledgement that men MPs are also fathering babies and indeed some male MPs carry on 'business as usual' when they have a baby.
"That is not acceptable and Parliament needs to set a proper example on leave.
"During my 35 years as MP I've had three children. Eighteen months' leave for three babies during 35 years' work doesn't seem too much to ask."