Labour is promising a "step-change" in women's working rights if it wins the general election, pledging an increase in the length of statutory maternity pay from nine months to a year.
The party also wants managers at large firms to be trained in supporting staff going through the menopause.
And it is promising the right to choose flexible working when starting a job.
The Conservatives say they would introduce "responsible reforms" to get more women into work.
Business Secretary Andrea Leadsom said Labour's "reckless plans would cripple businesses across the country".
Election campaigning is under way ahead of voters going to the polls on 12 December.
Shadow women and equalities secretary Dawn Butler said she was "sick" of the way women were treated at work, and that concerns had been ignored for "years".
She added: "Labour will deliver a workplace revolution to bring about a step-change in how women are treated at work. We'll boost pay, increase flexibility, and strengthen protections against harassment and discrimination."
Currently women on maternity leave are entitled to 90% of average weekly earnings for the first six weeks, then 90% of average weekly earnings or £148.68 (whichever is lower) for the next 33 weeks.
Labour says it will ensure women continue to get the latter rate for another three months.
The party also wants to create a Workers' Protection Agency, with powers to fine businesses that fail to report their gender pay or publish action plans to reduce pay gaps.
Figures from the Office for National Statistics indicate that, in the year to April 2019, the gender pay gap for full-time workers was 8.9% in the UK - up from 8.6% the previous year.
By law, companies, charities and public sector departments of 250 employees or more must publish their gender pay gap figures.
Labour says it wants to lower the threshold to workplaces with more than 50 employees by 2020.
Labour says it wants to transform the workplace for women. It's a powerful statement of intent from the party.
It's a policy pitched at a large chunk of the electorate. The proposals on maternity pay are obviously designed to appeal to younger women, who want to start or extend a family. But there are also plans for a "menopause policy", which will force companies to address the needs of women at a very different stage in their lives.
And then there are the measures to reduce the gender pay gap, and create a right to flexible working. That would affect pretty much every female employee.
Employers might complain about the bureaucracy and expense involved in much of this - "the wrong answers to the right questions" is how the CBI puts it - but there's no question there's a challenge here to the other parties.
Labour wants to be seen as the champion of working women. The rival parties will have to find ways to respond.
The party has reconfirmed a pledge made in February to give workers the right to choose their working hours from the first day in a new job. They can currently request this after 26 weeks in post.
Labour also wants companies with more than 250 employees to provide training for line managers on the menopause.
At its party conference in September, it said this should include understanding "what adjustments may be necessary to support" those going through it and making sure work absence procedures are "flexible to accommodate menopause as a long-term fluctuating health condition".
And it wants to make employers liable for sexual harassment experienced by staff by "third parties", such as clients, require employers to publish their policies and lengthen the timeframe within which employment tribunals can be taken from three months to six months.
But Business Secretary Mrs Leadsom said a vote for Labour "won't solve anything".
"Only the Conservatives will get Brexit done so we can all move on to focus on people's priorities like making the UK the best place to work and run a business with responsible reforms to increase flexible working, get more women back into work and ensure equality of opportunity regardless of gender, age, race or class," she said.
Matthew Percival, the CBI's director of people and skills policy, said: "The CBI has long supported the reintroduction of protection against third-party harassment and the extension of statutory maternity pay to 12 months - which will also support fathers taking shared parental leave."
But he added: "Needing government approval to set working patterns and company diversity action plans is bureaucratic to the point of being ineffective and unaffordable.
"They are the wrong answers to the right questions. The next government should work with business to develop policies that tackle gender inequality in ways that work for everyone."
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