Established as a one-woman concern in 1997, the company now has a workforce of six and a turnover of pounds 210,000.
But Miss Parker now fears this precarious success could be under threat from the Government's proposal to allow parents of young children up to 13 weeks of unpaid leave.
She is concerned that should Martin Sadler, her firm's training consultant, decide to have a fourth baby and opt for the childcare break it would leave a gaping hole in her business.
Mr Sadler is the only person in the company other than herself qualified in its core business of professional training and she said it would be impossible to recruit a qualified replacement at short notice.
T2, the firm she runs in Ascot, Berkshire, specialises in visiting companies and training their employees in intense two-hour sessions. Few people would have the experience for such a role and taking on a replacement would mean extensive retraining lasting between a week and a month - which would mean lost business. On top of that were the costs of hiring a competent temporary replacement - pounds 400 a day, against Mr Sadler's annual salary of pounds 25,000 to pounds 35,000.
Miss Parker, whose company registered a profit for the first time last year, said: "If Martin was to take three months off, the business wouldn't necessarily fail. But it would be extremely difficult to operate.
"Small businesses already have to be very flexible towards our employees, because we can't offer the perks such as pensions and health care. Now the Government wants us to be even more flexible, and there is just no more slack."Reuse content