The “just size up” myth, and what to do instead

It’s the most common piece of maternity advice, and it’s quietly wrong. Why sizing up leaves you in a tent, what actually changes when you’re pregnant, and how to dress the bump and the rest of you at once.

When you announce a pregnancy, the advice arrives before the congratulations have quite finished. Most of it is kind. Some of it is useless. And one particular piece of it is so common, so confidently handed over, that almost everyone believes it — right up until they try it and quietly wonder what they did wrong. Just size up, they say. Buy your normal clothes a size or two bigger and you'll be fine.

You will not be fine. You'll be swamped. And it's worth understanding exactly why, because the reason reveals what actually works instead.

Why the myth is so tempting

It's easy to see the appeal. Sizing up sounds logical — you're getting bigger, so buy bigger clothes, simple. It's cheap and low-effort: no special maternity shopping, no new brands, just a bigger number in the same shops you already trust. And it lets you keep wearing versions of your own wardrobe, which is comforting when so much else about your body suddenly isn't yours to control.

The logic feels airtight. It's just built on a false assumption about what pregnancy does to a body.

What actually changes (and what doesn't)

Here's the thing the myth gets wrong: you don't get uniformly bigger. You get bigger in one place. Your bump grows, dramatically and specifically. Meanwhile your shoulders, your back, your arms, your neckline, your calves — they stay more or less the size they always were.

So you don't need a larger copy of yourself. You need room in exactly one region and a normal fit absolutely everywhere else. And that is precisely the thing sizing up cannot give you, because a bigger size makes a garment bigger in every direction at once.

What sizing up really does to a dress

Picture a dress you love, bought two sizes up. The shoulders now droop off your frame. The armholes sag halfway to your waist. The neckline gapes open when you lean forward. The sleeves swallow your hands, the hem pools around your ankles, and the whole thing hangs from you like it's on the wrong hanger. You have added fabric to every part of your body that didn't need any.

And the cruel joke is that it still often doesn't solve the actual problem. A bump doesn't just need more cloth — it needs more cloth in a particular shape, curving out and up. Flat fabric cut for a flat stomach, even a lot of it, gets pulled tight and rides up at the front while drowning you everywhere else. The result isn't “pregnant and elegant.” It's “bigger all over,” which is the opposite of flattering — and it hides the one part of you actually worth showing off.

The real answer is engineering, not extra cloth

Proper maternity design solves the problem the myth can't, and it does it with clever cutting rather than more material. This is the entire reason the category exists.

An over-bump panel gives room precisely where the bump is — a soft, stretchy band that rises over the belly — while the rest of the garment fits you normally. Ruched side seams gather extra fabric along a channel that lets out slowly as the weeks pass, so one dress fits three different bump sizes. An empire line sits snug just under the bust and then falls away, skimming over the bump instead of clinging or tenting. A wrap ties at your narrowest point, above the bump, and adjusts endlessly. Every one of these is a small piece of engineering aimed at the same target: room where you're changing, ordinary fit where you're not.

The honest middle ground: forgiving cuts

Now, you don't need every single thing you own to be labelled maternity — and this is where the myth has a grain of truth buried in it. Some ordinary clothes genuinely do accommodate a bump gracefully, not because they're bigger, but because of how they're cut. A true A-line, an empire dress, a wrap, a relaxed shirt dress, a wide-leg trouser with a soft stretchy waist — these skim rather than cling, and they grow with you without turning into sacks.

The skill is telling the difference between a forgiving cut and a plain bag. A forgiving piece has a deliberate shape that happens to leave room for a bump; a bag is just big. One flatters, one drowns. Learning to spot which is which is most of the battle, and it's most of what we do for you.

How to actually choose

So here's the replacement for “just size up.” First, look at where a garment gets its room. Does the ease come from a waist seam that sits above the bump, from stretch, from a wrap, from a panel — a deliberate feature? Or does it come from simply being cut large everywhere? Only the first kind will work.

Second, trust maternity sizing when you buy it. A maternity size is usually your ordinary, pre-pregnancy size — the bump room is built in, so you don't size up on top of it. Sizing up a maternity garment is how you end up swamped all over again.

And third, when you do buy from the normal rails, chase the cut, not the number. Reach for empire, wrap, stretch and drape, and treat “I'll just get it a size bigger” as the warning sign it is.

The exception that (almost) proves the rule

There is one narrow case where sizing up sort of works, and it's worth naming so you can use it on purpose rather than by accident. A genuinely loose, unstructured piece — a floaty A-line dress, an oversized shirt, a swing top — was never relying on fitting you closely in the first place. Buy one of those a size up and you get a little more length and a little more sweep, and because it was cut to drape rather than trace, the extra doesn't read as “swamped.”

But notice what's really happening there: it works because the cut, not the size, is doing the accommodating. You're not sizing up a fitted dress to fake bump room; you're choosing a shape that had room to begin with and nudging it along. That's a completely different move, and it only works on pieces designed to hang. Try it on anything fitted, tailored or structured and you're right back in the tent.

A quick field guide to telling the difference

When you're stood in front of something online, wondering whether it'll grow with you or drown you, a few questions cut straight to the answer. First: where does the room come from? Is there a visible feature doing the work — a wrap, a tie, a stretchy panel, obvious give in the fabric, a waist seam sitting high under the bust — or is the garment simply cut large all over? Only the first kind will actually fit a bump.

Second: does it have a defined waist, and if so, where does that waist sit? A seam that lands at your natural waist will be strangled by a bump within weeks; a seam that sits up under the bust, empire-style, will skim happily over one for months. Third: what's it made of? Fabric with give forgives a growing curve; stiff cloth pulls tight across the front and rides up the moment there's something to climb.

And one last tell, once the thing is actually in your hands: put it on and move. Lift your arms, sit down, lean forward. A piece that will last a pregnancy stays put through all three — the hem doesn't hike up at the front, the neckline doesn't fall open, the waist doesn't bite. A piece that's going to fail does one of those things straight away, and it only gets worse as the bump grows. Clothes show you their future in the fitting room, if you ask them to move.

The point

Sizing up feels like the safe, sensible move, and it's neither. The goal was never to vanish into a larger amount of fabric. It's to dress the body you actually have — with real room where it's changing, and your normal, familiar shape everywhere it isn't. Don't size up. Size smart. That's the whole difference between looking like you're hiding, and looking like yourself, pregnant — and it's exactly the difference 9edits was built to help you find.