Female entrepreneurs are less numerous and raise less money than their male counterparts. Women make up 10 percent of the founders at high-growth tech companies, “and they raise 70 percent less money than men do because of their lack of access to capital,” says Lesa Mitchell of the Ewing Marion Kauffman Foundation, where she is vice president for initiatives on advancing innovation.

Ms. Roney says venture capitalists will assert that a female entrepreneur’s pregnancy and motherhood aren’t factors in deciding whether to invest in a firm — that it’s all about good ideas and the management team. “But I can pretty much guarantee you, behind closed doors it is a factor,” she says.

That is why, Ms. Roney says, “in those first moments of having a business and having a baby, the baby was a complete and total secret.”

At a start-up, which lacks much corporate infrastructure, founders typically do the jobs of at least five people. “The expectation of the devotion of your time, particularly if you are a founder, is that you should be doing this and nothing else — if you aren’t, you are not giving everything you have to the company,” Ms. Roney explains.

Ms. Fleiss was able to secure $15 million in Series B venture funding last year, shortly before she gave birth. If she had been pregnant as she pitched the company in the first round of financing, when it was still an unproved entity, she says she would have talked to mentors and advisers about how to present that fact.

Investors do need a full picture of a founder’s other life commitments, Ms. Fleiss contends.

“I don’t agree that men should be considered in the same exact context as women around aspects of raising a family,” she says. Certain factors like breast-feeding and body recovery require a women to take more time off, she notes. Ms. Fleiss took 10 weeks of maternity leave, she says, while her husband, Andrew M. P. Fleiss, a principal at the private equity firm Liberty Partners in Manhattan, took a week off.

Aileen Lee, a partner at Kleiner Perkins Caufield & Byers, the venture capital firm in Menlo Park, Calif., put it this way: “If someone was having some surgery that was going to put them out for three months, it’s something you should consider, with a man or a woman. What is the impact of having the C.E.O. or visionary out for three months?”