Like all mother-daughter relationships, the bond between Annie and Emily Cohen has its points of contention. Some recent ones have been over matters of fashion -- maternity tube tops, for instance.

In the Cohens' case, though, disagreement over encasing one's bulging torso in a strapless, stretchy chemise is strictly a business issue.

Emily, 29 years old, and Annie, 56, run a maternity-clothing boutique in suburban Detroit called Bella Belli. Annie says she was "shocked" when an order of brightly colored tube tops, placed by Emily, arrived one day. "I said 'Who in their right mind is going to wear these things?' " It is these little differences of opinion that cause Emily to say that "never in a million years" did she expect to go into business with her mother. But here she is.

Father-son partnerships are classic, but mother-daughter businesses are still somewhat novel. Certainly mothers and daughters have teamed up in commercial efforts going back generations, but not in any big numbers. Now, though, as it becomes the norm for multiple generations of women in a family to have professional expertise, the mother-daughter business is a more natural occurrence. No one seems to keep statistics on such enterprises, but people in the entrepreneurial world say their numbers are growing and that many are ventures far from the traditionally female realm, such as manufacturing and electrician companies.

While Emily's professional background is in social work and fund raising, she says she always wanted to own a store. A couple of years ago, many of her friends were getting pregnant and she noticed a lot of them were flying to Chicago to buy maternity clothes because they considered the local selection dowdy. Emily was childless and unattached, but she spied a business opportunity.

She called her mother, who had once co-owned a gift store. Annie says she had doubts -- among them some concern that a maternity boutique wasn't going to be a satisfying line of business for a single woman who might someday yearn for a family. Emily insisted it wasn't an issue. (She was, however, pleased when her sister became pregnant before the store opened last year, which focused her mother's interest in babies elsewhere.)

Emily convinced her mother to accompany her to a meeting with a fashion representative and to other shows. A venture was born.

Emily owns the store but considers her mother her partner. The two divide up the duties. Annie handles advertising, graphics and errands, while Emily handles the finances and most everything else. Ordering is still an issue, but the two say they complement each other. "She'll say, 'We have the tube tops, now we need the sweater sets,' " Emily says. And old mother-daughter roles often emerge, especially in the area of housekeeping. Annie is constantly sweeping the floor and cleaning the mirrors.

"She still wants to be my mother, even if we're in business," Emily says. "Sometimes she'll be like 'Put on lipstick," and I'll say, 'Mom, who cares if I have on lipstick?' "

But for her part, Annie says the partnership has helped her learn to back off and let her adult child figure it out. "I think you have to know when to not ask too many questions or not be too bossy," she says.

After a long day at the store, Emily often fields several more calls from her mother at home on everything from store inventory to the groomsmen's attire. (Annie wanted white dinner jackets; Emily settled on navy suits.) The other night they talked four times between 10 and 11 p.m. Emily's fiancé, incidentally, is in business with his father.