Melania Trump is hosting a lunch on International Women's Day on what is her first solo White House event as first lady.
The UN-designated day commemorates the push for women's rights.
Women across the US are observing the occasion by taking a day off work, as well as attending rallies.
At the White House, the first lady welcomed about 50 women seated at tables adorned with floral centrepieces.
Attendees included her daughter-in-law, Ivanka Trump, and vice president Mike Pence's wife, Karen.
In Japan, some 200 women gathered for a march to mark International Women's Day in Tokyo, protesting against low wages, long hours and other obstacles that make their lives difficult.
Participants, many of them members of women's groups and labour unions, chanted "It's hard to be a woman, and our patience is running out", and held up banners saying "Let's change our future".
Japan lags behind most other industrial countries in women's participation and advancement in business, academics and politics.
Prime Minister Shinzo Abe's "womenomics" policy aims to put more women to work to counter a chronically low birth rate and shrinking work force, but a business culture in which long hours are routine makes it more difficult for women to get ahead.
Meanwhile, the president of the European Parliament has used the occasion to promise that a Polish politician will be punished for the crude, sexist comments he made last week.
EU parliament President Antonio Tajani said that he intends to bring a "swift conclusion" to the probe into the remarks of Janusz Korwin-Mikke at the legislature and promised "a penalty commensurate with the gravity of the offence".
Mr Korwin-Mikke, a radical right-winger who leads a marginal party, said during a debate on the pay gap between men and women: "Of course women must earn less than men because they are weaker, they are smaller, they are less intelligent. They must earn less, that's all."
He could face sanctions such as a reprimand, a fine or a temporary suspension.
And scores of women working in the childcare industry in Australia walked off the job early to protest against what they deem to be inadequate pay rates.
The United Voice union, which represents the workers, said more than 1,000 at childcare centres in every state and territory in Australia stopped working at 3:20pm on Wednesday to call attention to wage disparities felt throughout an industry where the vast majority of workers are women.
"3:20 represents the time that Australian women ostensibly start working for free in comparison to men if you take into account the gender pay gap," said Helen Gibbons, the union's assistant national secretary.
"We know that this has traditionally been seen as women's work," Ms Gibbons said.
"It's 2017 and this is not OK to continue. The people who work in this sector demand equal pay."
In Italy, hundreds of women, with some men too, set off in a march from Rome's Colosseum to demand more respect.
Wearing pink wigs, scarves or headbands, they gathered on Wednesday evening by the ancient Rome arena. Among their demands: equal pay for the same work men do, and more executive positions in the corporate world.
Statistics show less than half of Italian women work. Many say they are forced to stay at home with small children because of a shortage of affordable day care, including public nurseries.
Meanwhile, the Swedish women's football team marked International Women's Day by replacing the names on the backs of their jerseys with tweets from Swedish women "who have struggled to gain ground in their respective fields".
The team that grabbed silver at the 2016 Olympics wore the blue and yellow jerseys with tweets by leading Swedes - including singer Zara Larsson - instead of the players' names at an Algarve Cup 2017 tournament in Portugal.
Swedish Football Association spokesman Niklas Bodell said the initiative "is first and foremost about showing the power in togetherness".