But then, in 1991, Demi Moore went and changed everything by posing naked for the cover of Vanity Fair when she was seven months pregnant.
From then on it became fashionable to show off your bump and shapeless maternity wear was quickly replaced by more flattering, form-fitting styles.
But although we've been saved from nine months of dungarees, we now have a new problem: there's so much more pressure for women to dress fashionably right up to the point that they go into labour.
Just ask actress Jennifer Garner, who is currently five months pregnant with her third child with Ben Affleck.
Unlike us civilians, Jennifer has the added problem of dressing her bump for the red carpet - and she recently admitted that her stylist, Rachel Zoe, has banned her from wearing maternity clothes.
She said: "Rachel Zoe is so determined to not put me in maternity clothes. I think because she was so little when she was pregnant, she didn't wear them.
"I have four months to go. Sooner or later, she is going to have to put me in a maternity dress. Eventually that is going to happen, but so far she has gotten her way."
In the last few weeks Jennifer has been seen at several events wearing fashion-fabulous dresses that aren't designed for pregnancy, including a one-shouldered Lanvin number and a short, black lace dress with sky-high bronze heels - and she looks great.
And considering that she's been dressed by the LA stylist who tweeted "Who says one can't rock 6 inch high leopard booties by Brian Atwood at 38 weeks pregnant!!", it's safe to assume that we're not going to see her in tracksuit bottoms and Uggs any time soon.
Same goes for Beyoncé, who has worn sequins, cut-out dresses and statement wedges since she announced that she's expecting. Hers is undoubtedly the most glam bump in the business, so we shouldn't be surprised that she's now planning to launch her own line of maternity wear.
And where celebrities go, the rest of us tend to follow.
The success of maternity ranges from fashion-forward high street stores like TopShop proves that British women really do want to wear the latest trends when they're expecting.
"Many women feel wonderful when they are pregnant, with great hair, glowing skin and bags of energy. It just doesn't feel right to hide away wearing a shapeless sack - they want to look like they're pregnant, not fat," says stylist Abigail Bowen.
"Just because you're pregnant, you don't have to lose your identity. So if you love a bit of leopard print, you can treat yourself to an amazing clingy dress or a fab pair of shoes. If you're a magpie, you can pile on the sequins and layer up jewellery to the max. Carrying a baby is something to be celebrated, so it's important to enjoy it."
But while it's true that you're more likely to feel better during your pregnancy if you make a bit of an effort, there usually comes a point where you no longer care what you wear as long as it fits.
That's when most women embrace the late pregnancy wardrobe of leggings, T-shirts, baggy jumpers and comfortable shoes.
And I'd like to think that's why some celebrities - Victoria Beckham is a good example - vanish from public view in the weeks before the birth.
Given a choice between tottering down the red carpet like an egg on legs or sitting at home with your feet up, I reckon that even Posh would decide that it's best to stay on the sofa.
After all, this is one of the only times in your life when you have a good excuse to spend days in your pyjamas - and it would be a shame to let the opportunity go to waste, wouldn't it?
Especially if you're going to be on a mission to get back into your pre-pregnancy gear soon after you've given birth...
What do you think? Are we under too much pressure to look super stylish when pregnant? Should it be one time we can just relax and enjoy rather than trying to jemmy ourselves into LBDs and heels?
More:Is It Just Me?
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