I'm not particularly into her normal everyday style, but she makes the most of her laidback California style when she's pregnant. I figure since I'll be at my biggest during the summer, she'll provide practical inspiration.
Wear what you normally wear
Of course, some styles just aren't going to work during this time (like the sweet vintage look of tops tucked into high-waisted shorts), but there's usually some facet of your normal style that could carry over. For me, the bohemian, granola look would work. I think with so many changes going on, it's important not to abandon everything familiar. I'd like to look into the mirror and still recognize myself.
She wears a lot of these loose Indian dresses that skim the body and accommodate a growing waistline, but aren't absurdly voluminous because of the light cotton fabric. I think these dresses are so much better than the maternity dresses I've looked at online, which seem to work only to showcase the belly. I'm not against an empire waist or two, but in general, a nipped-in empire waist silhouette tends to look slightly infantilizing and off-balance. They also remind me of my black Molly fish when she was pregnant, but that's just me.
To avoid frumpiness, I think it's best to drop the hemline while exposing the shoulders and clavicles.
I used to work at a bagel shop in the summers in Texas, and there was a girl there who just wore increasingly large tee shirts during her pregnancy. No one says that you have to be stylish when you might be feeling miserable and gravid, but she did look rather sloppy, whether or not she cared. And after some experimentation, I've decided that while looking visibly pregnant at this point might be useful in some situations, like when trying to navigate a crosswalk (my biggest pet peeve in this town is how no one slows down for pedestrians. Seattle was so much more pedestrian-friendly, even being 20 Xs larger, according to the latest census), I've never dressed much for attention and I'd rather not start now.
Of course, at some point, it can't be helped. But I find that with exposed arms, shoulders, or legs--body parts that tend to remain their normal size during pregnancy--a pregnant body can still look balanced. They provide a nice counterpoint to all that extra fabric around the middle.
I notice that if I wear designated maternity clothes, I look so much more pregnant than if I just wear my normal clothes. I also find those black elastic panels rather depressing to look at, so I avoid them if at all possible. I may have to resort to them when I'm late in the third trimester, but for now, I just size up several sizes.
Luckily, I've been able to dig around in my closet for my oversized clothing. Buying clothing targeted to a late twenties to middle-aged demographic also seems to work, since these tend to be cut generously with certain trouble spots that coincide with pregnancy (thighs, stomach) in mind. Anthropologie is a good source, as is Flax. I'm thinking Ann Taylor Loft and Chico's would be good for mall brands, but since I don't shop there normally, I haven't checked them out.
I'm against buying a whole new wardrobe for just a few months (as Thoreau says, "beware of all enterprises that require new clothes, and not rather a new wearer of clothes"), but for some pieces I've found it necessary, in which case I go to the cheapest source possible. I recently bought a pair of size 8 shorts from Old Navy, which I wear with a belt instead of resorting to the black panel. For when I do need a panel, I think I might just use my short jersey miniskirt from American Apparel, folded in half, as a DIY alternative to the belly bands. Unlike the linen pieces I bought recently, I'll probably not be wearing these shorts again post-pregnancy. But who knows?
In the above pic, Nicole is wearing normal clothes from Urban Outfitters (left) and Rick Owens (right). I'm not too sure about wearing designer clothes like that unless you're a Vogue editor or minor celebrity who is willing to retire them after a few months of wear, when they get stretched out. But the RO dress does illustrate the way that bias cut fabric can work just as well as an empire waist to accommodate your shape, and with a much more chic silhouette.
Okay, so I'm really just posting this pic because I adore the dress, which looks cool, easy, and colorful, and something I'd wear regardless of my pregnant state. I've asked my friend to see if she can find one of these type dresses when she goes to India to visit family this winter. It'll be too late to be useful, but it would be nice in upcoming summers. Vintage dresses like these go for around $100 on eBay nowadays, which goes against all my thrifting ethic.