The gender pay gap for women in their 20s has halved to 5%, new research shows.
But it's a different story for women in their 30s and 40s as they start to have families.
Despite the pay gap closing when women begin their careers, the enduring "pay penalty" for when they have children remains, the report said.
And women will still earn "significantly" less than their male counterparts over their careers, the study by the Resolution Foundation found.
Baby boomers, those born between 1946 and 1965, experienced a pay gap of 16% during their 20s, falling to 9% for women born between 1966 and 1980 and then 5% for those born between 1981 and 2000 - described as 'millennial' women.
Despite this progress in the early career phase, the gender pay gap continues to rise rapidly for women in their 30s and 40s, said the foundation.
Senior policy analyst Laura Gardiner said: "Young women today face relatively little disadvantage in terms of their pay packets compared to what their parents' and grandparents' generation faced.
"But while many millennial women haven't experienced much of a pay gap yet, most probably will once they reach their 30s, when they start having children.
"What's more this pay penalty is big and long-lasting, and remains for younger generations despite the progress in early careers."
A Government spokeswoman said: "The gender pay gap is at a record low but we have to push further to eliminate it completely.
"Shining a light on organisations' pay gaps means employers can take action to tackle the causes and drive change.
"That's why we are introducing requirements for all large employers to publish their gender pay and bonus gaps data from April this year."