These days, that's just how stylish mothers-to-be are treating their bellies when it comes to dressing: as an exciting accouterment rather than an insurmountable style obstacle. These resourceful women are mixing non-maternity pieces from surprisingly pregnancy-friendly labels such as Alexander Wang and Rick Owens with a chicer-than-ever crop of maternity brands.

In the age of the Best-Dressed Baby Bump, it's hard to fathom that Lucille Ball caused a scandal when she appeared pregnant on 'I Love Lucy,' in 1952, or that Grace Kelly used her Hermès bag to shield her growing body from the press. 'Things have changed so much over the last few decades,' said Violet Gaynor, a senior fashion editor at Instyle.com and co-founder of the Glow, a website that features at-home interviews with chic mothers like actress Jemima Kirke and Manhattan boutique owner Maryam Nassir Zadeh. Ms. Gaynor and her co-founder, Kelly Stuart, will be releasing the Glow's first book in April. 'There's so much more of a celebration about being pregnant,' she added, 'and more of a focus on stylish motherhood.' Websites like the Glow offer mothers plenty of fashion inspiration-often with shoppable links.

As the average age of first-time mothers continues to climb and the number of women having children in their 30s and 40s rises, ladies with a well-developed sense of fashion see no reason to sacrifice personal style when they're expecting. And the fashion industry is responding.

'There is this group of women who have more disposable income to spend. They have their own identity and style and are really looking to preserve that,' said Courtney Klein, a former partner at a Manhattan digital agency who recently launched Storq, a collection of layerable, curve-hugging basics designed to fit into women's existing wardrobes-not replace them altogether. Storq's stretchy modal pieces-skirt, dress, leggings, tank top-can be purchased separately, or as a complete set for $195, on the brand's website. Ms. Klein, who is 28 weeks pregnant herself, has already shipped orders to 30 states.

Ms. Klein is just one of the entrepreneurs helping to rewrite the script for pregnancy dressing. Ariane Goldman, who founded the label Hatch in 2011, said the word 'maternity' is taboo in her office. 'I think all of us just associate 'maternity' with disposable pieces that will get you through this icky stage and that you'll never want to wear again,' said Ms. Goldman. Instead, Hatch aims to provide pieces-at prices similar to what one may pay at, say, A Pea in the Pod, where many dresses hover around the $200 mark-that will live on in a woman's wardrobe after pregnancy. The appeal of Hatch's silky jumpsuits, gaberdine trenches and flowing dresses is apparent, whether a customer is pregnant or not.

Ms. Gaynor said the fashionable mothers she has featured on the Glow taught her the value of an 'anything goes' approach. 'They like to find what works for them and just go with it,' she said, 'even if it's not a traditional approach to maternity.' For Ms. Gaynor, whose daughter was born last summer, that meant not only investing in the ubiquitous J. Brand maternity jeans, but resurrecting favorite pieces from her closet, like a generously cut Emilio Pucci dress that once belonged to her grandmother. Another of her favorite looks was a long white Alexander Wang slip dress, which she bought a few sizes too big, that wraps under the bust.

'There's something reassuring about still being able to shop in a regular store when you're pregnant,' said Meredith Melling, who recently left her longtime post as a Vogue editor to co-found the fashion consultancy firm La Marque. Ms. Melling, whose second child is due this weekend, said she has relied on American Apparel unitards and oversize cardigans, as well as items from Zara, which she buys big and has tailored to fit her growing body. For special events, Ms. Melling swears by vintage clothing. Unlike with current-season wares, she said, there are no preconceptions about styling or fit and little risk of another (un-pregnant) woman appearing in the same dress. However, for the very special occasion of the La Marque launch in January, Ms. Melling wore a current Marc Jacobs dress with a drop-waist-a universally flattering silhouette for party-going pregnant gals. 'It was a way to feel a bit more elevated, like my former fashion self,' she said.

Kate Davidson Hudson, co-founder of the luxury accessories website Editorialist, recently traveled to Milan and Paris Fashion Weeks while she was more than five months into her pregnancy. She found herself packing pieces from designers who favor boxier shapes, including a snakeskin-printed shift dress from Stella McCartney. 'There are ways to play around with sizing with contemporary and designer brands so you still feel like yourself, but don't look like a sausage squeezed into a runway look,' said Ms. Davidson Hudson, adding that it's better to wear more fitted items as your bump grows, counterintuitive as it may seem. 'You almost need something body-con when you get to seven or eight months, to define the belly,' she said. A body-skimming knit dress from the designer Rick Owens that had languished in her closet for seasons proved pivotal during her first pregnancy, in 2011. In addition to his edgy aesthetic and penchant for leather, Mr. Owens is known for his neutral color palette and use of forgiving fabrics.

Laure Heriard Dubreuil, founding partner of the Miami boutique the Webster, is also a fan of Mr. Owens, as well as Azzedine Alaïa bodysuits, for expecting moms. 'I learned that it's better to wear tighter clothes,' said Ms. Heriard Dubreuil, citing a particularly ill-advised oversize gown that made her feel frumpy at a formal event. 'Most of [Owens's] pants or skirts have elastic bands, so you can wear them low-waist,' added Ms. Heriard Dubreuil, whose son was born in January. 'The drop crotch of his pants also works well, so you have a cool look.'

Slip dresses are another of Ms. Heriard Dubreuil's go-tos. After falling in love with a long bias-cut version she found at C. Madeleine's, a vintage store in Miami, she had her tailor reproduce it in several other colors. She wore the original (and her copies) under a Balenciaga leather jacket or long cardigan from Acne. 'They are perfect when you're pregnant, because your cleavage looks beautiful and you show your belly,' she said.

Looking good may be directly correlated to feeling great, but so is being physically comfortable-especially in your third trimester. Nadiyah Bradshaw-Spencer-a production director for the Manhattan clothing label Suno-is due this month with her first baby. She's long since abandoned her suede Nicholas Kirkwood stilettos in favor of ankle boots from the same designer with a small, foot-friendly block heel. Actress Ms. Washington appreciates comfort as well. 'It's been fun to explore how to fuse comfort and fashion in a different way,' she said. 'That's why tailoring is so important.'

Ms. Heriard Dubreuil, of the Webster, made concessions to comfort during pregnancy too, swapping her heels for sneakers from Pierre Hardy, and ditching her heavy bags for Olympia Le Tan clutches. As she prepared recently to travel to Paris for Fashion Week with her son, the new mother said she was packing those sneakers, but that the Olympia Le Tan clutches were staying at home. 'Unfortunately,' said Ms. Heriard Dubreuil, 'they can't fit the diapers.'