I was reading this article again:
https://www.tvnz.co.nz/one-news/new-zealand/hillary-clinton-s-classic-kiwi-baby-gift-jacinda-ardern-revealed-prime-minister-v1
and in it she is referred to as Ms Clinton.
"Prime Minister Jacinda Ardern kept her discussions with former US Secretary of State Hillary Clinton close to her chest, but revealed today during a press conference the Kiwi-themed gifts they exchanged.
The pair had an hour-long breakfast meeting this morning, prior to Ms Clinton speaking at 'An Evening with Hillary Rodham Clinton' at Spark Arena this evening.
Ms Ardern said she was "unlikely to go into the detail of the conversation", however, they "had a good discussion which included some domestic policy here in New Zealand, the future of work for instance, geo-political environment, and also being a mum in the political frame".
They exchanged gifts, with Ms Clinton giving Ms Ardern "a gift she was told every New Zealand child needed to have" - a buzzy-bee.
Ms Ardern gave Ms Clinton children's books for her to read to her grandchildren, including Hairy Maclary From Donaldson's Dairy and A Summery Saturday Morning, by New Zealand authors Lynley Dodd and Margaret Mahy respectively. "
Jacinda Ardern is referred to as Ms Ardern even though Clarke Gayford is her baby dady.
https://www.stuff.co.nz/national/politics/100720699/jacinda-and-clarke-the-familyfocused-first-couple-of-nz
Wondering why she is referred to as Ms I found this:
Is Hillary Clinton a Mrs. or a Ms.?
by Pete Kasperowicz | October 28, 2016 12:01 AM
Hillary Clinton's historic run as the first female major party presidential candidate has highlighted a small but nagging problem for news outlets: Is she Mrs. Clinton, or Ms. Clinton?
The Wall Street Journal, for example, seems to use both, as some stories call her " Mrs.," and others call her " Ms."
Other news outlets have a style preference, but can still look inconsistent if they quote people who don't stick to the rules when they speak. The Washington Post editorial board calls her "Ms. Clinton," but has also run several stories that quote others calling her "Mrs. Clinton."
But there are some rules. The Associated Press, which many news outlets use as a style judge, says "courtesy titles" like "Mrs." and "Ms." shouldn't be used at all unless a woman requests that they prefer one or the other.
That guidance somewhat blurs the traditional distinction between the two titles, as "Mrs." is generally seen as a title for married women, while "Ms." was usually associated with unmarried women. Some newer guidance that can be found online says "Mrs." always means a married woman, but that "Ms." can be used for both married and unmarried women.
The AP guidance tries to simplify it by letting women have what they want.
"Refer to both men and women by last name, without courtesy titles, in subsequent references," according to the guidance. "Use the courtesy titles Mr., Miss, Ms. or Mrs. only in direct quotations or after first reference when a woman specifically requests it: for example, where a woman prefers to be known as Mrs. Smith or Ms. Smith."
And when it comes to differentiating between, say, Hillary Clinton and Bill Clinton, the AP advises reporters to use their full names, without a courtesy title.
The New York Times has adopted a slightly different version of the AP's system, and explained that it automatically refers to women as "Ms.," until they express a preference. The Times believes "Ms." is more "progressive," and will stick to that title until told otherwise.
"It's the women who get to choose their courtesy titles at this modern institution," the Times wrote. "According to The Times's internal rules, women will be referred to as 'Ms.' unless they've elected to be a 'Mrs.'"
The Times noted that its rules can lead to different final results for different people. But both Hillary Clinton and Michelle Obama chose "Mrs.," and the Times indicated Clinton's choice surprised some on the Left.
"Hillary Clinton, one might think, would chose the more progressive title 'Ms.' the Times said. "But she prefers 'Mrs.'"
https://www.washingtonexaminer.com/is-hillary-clinton-a-mrs-or-a-ms