MONEY mummies, kitchen table tycoons, mum magnates - whatever you want to call them - they're certainly a force to be reckoned with.

Mums who decide to start a business while they are pregnant or shortly after giving birth are now generating £4.4bn annually for the UK economy, according to a new study.

A famous example is Friends Reunited, the cult website dreamed up by Julie Pankhurst in 1999 when she was expecting her first child. During her pregnancy she became curious about what her old school friends were up to. The business eventually sold seven years later for £175 million.

"The main reason is they want more flexibility and motherhood changes their priorities. Thirteen per cent said they felt ready for a new challenge," said Emma Jeffs from Yell.com who commissioned the research.

By 2010, Barclays expects female entrepreneurs to outnumber their male counterparts in the start-ups in some major industries.

Traditionally, women were far less likely to show entrepreneurial spirit than men and branch out on their own.

Achieving that elusive work/life balance, escaping the cost of childcare or plugging a gap in the market are among the reasons so many mothers are now going it alone.

Psychologist Dr Geoffrey Beattie also believes that it's the changes a woman goes through while pregnant that are a key catalyst.

"It can elevate your mood for significant periods of time. When people are in an elevated mood state, they are prepared to consider riskier types of initiatives such as launching a business. This can lead to the translation of an initial break-through idea into action."

But Jo Spragg, who has three children and runs Kite Kids, an organic children's clothing company based in Poole, feels it was the flexible working hours, rather than her hormones, that motivated her.

"To be able to fit my working day around my family life was the most important thing. I would say the lows are far worse than when you are working for someone else but the highs are so much higher."

Jackie Whitley, who has two daughters and runs Yummy Mummy, a party plan company, said she and business partner Laura Maunder started talking about going into business together while they were still on maternity leave.

Although they are currently working part-time in the civil service, they hope their business will become a full-time venture.

Jackie writes: "As I type this email, my youngest is napping and will be waking soon - and then I will be off to collect my other daughter from school. I will then be back at work on the lap-top at the kitchen table tonight after the girls have been fed, bathed and put to bed."

According to the research, 40 per cent of mums surveyed wanted to start a business while pregnant or within a year of the baby being born but 22 per cent of them initially had trouble securing funding because of their mum status.

One study found that mums perform around 18 different job roles - from cook right through to accountant - during any average week which is estimated to be worth a combined salary of around £50,000.