Watch: The touching moment Trevor Mallard holds Labour MP's baby while sitting in Speaker's chair

Parliament's Speaker Trevor Mallard has propped the three-month-old daughter of a Labour MP colleague on his lap while supervising today's night session of Parliament.

The gesture had a symbolic element, as Labour MP Jenny Salesa spoke about Labour's recently announced Paid Parental Leave Bill.

Sitting next to each other, the two MPs held their babies during the first sitting day of Parliament. Source: 1 NEWS

With a slight grin on his face, Mr Mallard looked relaxed and to be enjoying having the three-month-old baby of Labour MP Willow-Jean Prime on his lap.

Young Heeni, likewise, seemed totally at peace while being slowly rocked in Mr Mallard's arms.

Mallard has "bagged" the first cuddle from the seven-week-old baby. Source: 1 NEWS

Despite being wide awake, Heeni remained completely calm and silent.

The bill being discussed in Parliament will extend paid parental leave from 18 weeks up to 22 weeks next July, and to 26 weeks by July 2020.

"The Paid Parental Leave and Employment bill is about recognising the importance of bonding between infants and their parents, between Speakers of the House and infants," Ms Salesa said.

"It is about recognising our children have the best possible start in life, it is about doing what is right."

Following Ms Salesa's speech, National MP Judith Collins also commented on baby Heeni's appearance.

"I thought the baby was very good and didn't cry either," Ms Collins said.

Prime Minister Jacinda Ardern said the bill is part of the Labour-led Government's promise to better support working families with new-born and young children.

Yesterday, Opposition Leader Bill English said he will support the bill, despite vetoing a bill by Sue Moroney with the same leave extension in June last year.

"We'd always said we would extend as there was the capability to do so," Mr English said.