Having found herself in the midst of tough coalition negotiations after a closely fought election, Jacinda Ardern was facing far more than her political colleagues could have guessed.



Six days before becoming New Zealand’s prime minister-elect, the Labour leader discovered she was pregnant, but was desperate to keep it, and the accompanying morning sickness, a secret during the post-election maelstrom.



Asked how she managed, Ardern replied: “It’s just what ladies do”, evoking the sympathy of women the world over who just get on with it while struggling with first-trimester nausea.



The 37-year-old worried her staff might notice she was eating constantly, and only the same foods. “But no,” she revealed, “apparently people thought I was just a woman of odd habits,” she told stuff.co.nz.



No one, it seems, rumbled her. “None of them noticed I had pretty bad morning sickness while negotiating our government,” she told Sky News.



News that Ardern will give birth in June – shortly after which her television producer partner, Clarke Gayford, will become the primary caregiver – has been hailed as a thrilling landmark.



“Exciting news!” tweeted Labour’s Harriet Harman, the UK’s longest-serving female MP and the first pregnant candidate to win an election in 1982. “Pregnant prime minister & stay at home dad! New Zealand leads the way! Congrats all round.”



Scotland’s first minister, Nicola Sturgeon, said the announcement, though foremost a personal moment for Ardern, “also helps demonstrate to young women that holding leadership positions needn’t be a barrier to having children (if you want to)”. And the former UK Green party leader Natalie Bennett saw it as “another landmark passed for women in politics”.



Ardern said she did not think her position was that different to others’.

“I’m not a trailblazer,” she said. “I am not the first woman to multitask. I am not the first woman to work and have a baby. I know these are special circumstances but there will be many women who will have done this well before I have.



“And, New Zealand is going to help us raise our first child … I think it’s fair to say that this will be a wee one that a village will raise, but we couldn’t be more excited.”



Ardern, once a policy adviser to the former British prime minister Tony Blair, broke the news on Instagram and Facebook, posting a photograph of three fish hooks, two large and one small, in reference to Gayford’s passion for fishing. He is host of the popular TV show Fish of the Day.



In the post she said: “I’ll be prime minister and a mum, and Clarke will be ‘first man of fishing’ and stay at home dad. I think it’s fair to say that this will be a wee one that a village will raise, but we couldn’t be more excited.”



She will take six weeks’ maternity leave – rather that the 22 weeks of paid paternal leave to which New Zealanders are entitled – during which the deputy prime minister, Winston Peters, will take over. She will, however, remain “fully contactable” throughout, and intends to resume full prime ministerial duties on her return.

Ardern is one of only a handful of world leaders to give birth in office. Pakistan’s Benazir Bhutto delivered her second child while in office in 1990.

Quick guide Benazir Bhutto on giving birth as leader Show Hide In July 1988, Pakistan's president, Muhammad Zia-ul-Haq, announced the country's first elections in more than a decade. His chief opponent, Benazir Bhutto, having said weeks earlier she was expecting her first child, did not see a coincidence. "General Zia called the [elections] thinking that a pregnant woman couldn't campaign,” she told the BBC. “I could, I did and I won, so that disproved that notion." Her exhausting campaign schedule was only momentarily interrupted when her son was born four weeks early. The decisive win proved that voters could accommodate the idea of a new mother running the country – though it helped that Bhutto was a formidable character from a powerful political dynasty. Bhutto became the first democratically elected leader to give birth while in office when her second child arrived in 1990. She had the baby secretly, fearing opponents would use her absence to move against her. "The next day I was back on the job, reading government papers and signing government files." She had been pregnant with her third child during political upheaval in which she was teargassed. “It was a pretty harrowing experience,” she said. “[But] I found that the old-fashioned notion that a woman who's expecting a child has to be bedridden was absolutely wrong, a woman can do anything if she's lucky enough not to have morning sickness." Photograph: Robert Nickelsberg/Hulton Archive

Ardern and Gayford had been told they needed help conceiving, and put plans on hold when she was promoted to Labour leader in August. They discovered she was pregnant on 13 October and she was sworn in as prime minister two weeks later.

Asked if the news had weighed on her during coalition negotiations with the New Zealand First party, she replied: “I am human. Whose mind wouldn’t it play on?”



The couple, however, were delighted with the news. “We wanted a family, but weren’t sure it would happen for us, which has made this news unexpected but exciting,” she said.



Within days of becoming Labour leader, Ardern was twice asked by television hosts about her plans for children. One questioned whether it was acceptable for the country’s leader to take maternity leave while in office, claiming most employers would want to know about their workers’ maternity plans.



Ardern, who had previously talked about the difficulties of juggling political life with wanting to start a family, made clear such questions were “unacceptable” in the workplace in 2017.



Before becoming New Zealand’s youngest prime minister since 1856, and its third female leader, she acknowledged it would be “difficult” to be a parent as well, but said: “I don’t think they are mutually exclusive” and “if we want parliament to reflect New Zealand as a society, then we should be able to accommodate both”.



The former prime minister Helen Clark, tweeted her congratulations, adding: “Every woman should have the choice of combining family and career.”

In New Zealand, which in 1893 became the first country in the world to give women the right to vote, the people seem proud of once more putting equality on the world map.



Ardern, meanwhile, is insistent her maternal responsibilities will not conflict with those to her country, and she will deliver on both. “I know, because of who I am, that I will do the job that I’ve been asked to do, that I have a mandate to do. Nothing’s going to change that.”



• This article was amended on 29 January 2018 to correct a misspelling of Helen Clark’s surname from Clarke.

