It follows warnings from fertility watchdogs that too many IVF clinics are exploiting older women, by "trading on hope" when just two a year will achieve success, after the age of 44.
Dr Stewart said employers should do more to assist family-friendly working - including provision of creches - instead of encouraging women to freeze their eggs.
She said corporate policies offering subsidised egg storage were a "disingenous" way of persuading workers to delay starting a family, creating the illusion that fertility could be safely put on ice.
The chairman of the British Fertility Society urged major companies to do more to allow workers to combine careers with parenthood, rather than feeling that they should scale the corporate ladder first.
Speaking ahead of the world's leading fertility conference, which meets next week in Vienna, she urged employers to do more to allow women to combine work with motherhood.
"I think we need to make it easier for parents to bring children to work. Why don't big companies have childcare built in? Some of these have huge amounts of money," she said.
Dr Stewart suggested that eye-catching policies - such as subsidised egg-freezing, which is offered by companies such as Facebook and Apple - could backfire. Such policies could put pressure on women to defer having a family, even though later fertility treatment using the frozen eggs might not work.
She said: "It strikes me as a false economy and in some ways rather disingenuous," questioning who would fund ongoing storage if women wanted to leave their jobs.
"It suggests that it is a good thing to delay family with these eggs in the bank for security - which of course is not the case since delaying is not always positive and certainly no guarantee," she said.
Employers would do better to offer fair pay and easy provision of childcare, said the UK's NHS fertility specialist, who said that most of her salary during was spent on her nanny while her own children were growing up.
Dr Stewart said that for many women who sought motherhood, the struggle to find the right relationship, and the desire of some men to delay becoming a parent also played a part.
"It's not just to do with careers, its to do with finding the right guy to have a family with," she said.
In her own role as an reproduction specialist, working for Newcastle Upon Tyne Hospitals NHS Foundation trust, she spends a lot of time urging those with compromised fertility not to waste any time.
She said: "When I have women whom I know are going to have potentially shortened reproductive potential - because of a medical problem or something like that - I would say if you are in a position to have a family don't [put it off to] travel around the world, take the baby with you. Fertility can change quicker than you think."
The average age of mothers is now 30, four years older than in the 1970s.
On current trends, the number of pregnancies to women in their 30s will soon outnumber those among women in their 20s.
Dr Stewart also urged the UK's NHS to do far more to assist those with fertility problems, describing IVF rationing in England as a "a shambles".
In England, the National Institute for Health and Care Excellence recommends that the NHS funds three cycles of IVF for women under the age of 40. But just 12 per cent of Clinical Commissioning Groups comply with this, a fall from 24 per cent in 2013.
Dr Stewart said attempts to save NHS funds by refusing IVF treatment were "shortsighted" - especially given the impact of involuntary childlessness on mental health.
"It should be an NHS thing the same as anything else. I really struggle to understand people who say it's a lifestyle choice."
She also warned that the growth in rationing has fuelled an increasingly aggressive commercial sector.
"People come to us and it's sometimes quite heartbreaking the stories they tell us," she said.
"They haven't had good advice."
In particular she is concerned by growing numbers of overseas clinics coming to Britain to target infertile couples, often at commercial fertility shows.
In many cases, such operators were able to persuade infertile couples that combining treatment with a beach holiday would boost their chances - neglecting to be transparent about their actual risks and success rates.
"They will describe it as a fertility holiday and that always seems quite attractive to people because they are worried about the stress associated with fertility treatments so if you can go and do it on the beach, well why not?"
Such clinics sometimes focused on high conception rates rather than the number of successful births - because they used riskier approaches, such as multiple embryo transfer, than are normally used in Britain, she said.
Dr Stewart also raised concern about false claims being made by purveyors of alternative medicine.
"There are things that are just nonsense," she said, raising concern about the merits of uterine massage, crystals, diets and drinks that are offered.
"It's fine to have complementary medicine but you shouldn't make claims that it will improve fertility," she said. "We see this pushed at some of these shows.
