'I hope she gets space' - Bill English on Jacinda Ardern's pregnancy

National leader Bill English says he hopes Prime Minister Jacinda Ardern will be treated graciously as she juggles leading the country with motherhood.

Mr English, who had six children aged under 14 while he was opposition leader in the early 2000s, offered encouragement to her colleagues to treat her with care as she manages the struggles of parenting.

Asked what advice he'd give to his successor as leader of the country, Mr English told The AM Show on Tuesday morning that she deserved space to take her job as a mum as seriously as her actual job.

"Having a child brings joy to your life, but challenges as you're fronting the public every day," he explained.

"I just hope the Prime Minister gets the space to be able to conduct relatively normal family life."

Mr English says Ms Ardern shouldn't be held to higher standards just because of her role, and ought to be treated graciously as she acclimatises to motherhood.

"I hope she gets the space to be able to do some of the things other people do, like turn up to work tired and not get a hard time for it," he said.

Mr English offered his congratulations to Ms Ardern and partner Clarke Gayford when she announced her pregnancy last Friday.

"Mary and I would like to extend our sincere congratulations to Prime Minister Jacinda Ardern and her partner Clarke Gayford on the news of the Prime Minister's pregnancy," he wrote.

"It is an incredible privilege to be a parent. A new child will bring real joy to their lives. We wish them all the best."

Ms Ardern's baby is due in June.

Newshub.