Despite the hilarious Knocked Up scoring well at the local multiplex, we're not feeling all that pregnant with jubilation when it comes to Mothers Work (NASDAQ:MWRK). The maternity apparel retailer saw its stock close 5% lower yesterday, after posting a 3.6% slide in comps for the month of May.

This may seem to be sequentially better than the cruel 14.8% comps debacle that the company posted for April, but after talking down its full year guidance back in April, it's just one more step down during the company's tough gestation period.

Are folks just not as preggers as they were last year, or is Mothers Work simply shedding market share? The company appears to be conceding the last point. It points to non-maternity fashion trends like trapeze and baby-doll dresses and tops that can double admirably as maternity wear early in pregnancies.

It's a shame because the retailer seemed to be making all of the right moves. Between opening "store in a store" concepts inside Macy's (NYSE:M) department stores and establishing itself as the exclusive maternity wear provider at chains like Sears (NASDAQ:SHLD) and Kohl's (NYSE:KSS), Mothers Work was establishing itself as the master purveyor of clothing for expectant women.

Even its clever futuretrust program with MasterCard (NYSE:MA) got high marks from me earlier this year. How can one dispute the logic of Mothers Work trying to get pregnant customers to link up their credit cards with tax-advantaged 529 college savings plans?

However, the water breaks if the urgency to snap up new maternity dresses isn't there. Short of trying to win back the crowd by writing What You're Expected to Wear While You're Expecting, it's going to be tough to woo investors even if your shares are attractively priced at 11 to 13 times this year's bottom-line guidance.

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Longtime Fool contributor Rick Munarriz hasn't had a pregnant wife for nearly nine years now, but he does remember spending time at maternity stores. He does not own shares in any of the companies in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.