Maternity sizing is genuinely confusing. Your body is changing faster than any other period of your adult life, often week by week. Standard size charts don't account for what's happening to your belly, bust, hips, and waist simultaneously. And buying something that fits at week 20 is no guarantee it'll fit at week 32.
Here's how to approach it without guessing.
Why standard sizing doesn't work during pregnancy Most clothing is sized for a body that's relatively static. A size medium assumes certain measurements across the bust, waist, and hips that more or less hold week to week. During pregnancy, none of those assumptions hold. Your belly is growing fastest, but your bust may also be increasing significantly — for many women, one to two cup sizes by the second trimester, sometimes more by the time milk comes in. Your hips and waist follow their own timeline. You are not the same size across three trimesters, and you're often not the same size as the maternity chart expects you to be.
In research conducted with Indian women across three life stages, fit was cited as the second-highest purchase barrier overall — and by the third trimester, nearly 78% of pregnant women listed fit as a reason they hadn't bought maternity wear. This isn't a personal body problem. It's a category-wide design failure.
The overbelly vs underbelly question This matters more than most people realise. Underbelly waistbands sit below the bump — they're common in regular maternity leggings and can feel fine in the first trimester. By the second and third trimester, they dig in, roll down, and need constant readjusting. Overbelly panels fold over the bump and sit at the natural waist. They're more comfortable across all three trimesters and into postpartum. If you're buying maternity bottoms, overbelly is almost always the better choice. Look for it specifically — it's not always the default.
How to size across trimesters The general principle: buy for where you're going, not where you are. If you're at week 14, buy for week 24. Pieces with real stretch — cotton with 5–8% elastane, not just regular jersey — will accommodate that range without looking baggy early on. Avoid buying too tight in the hope of wearing it longer. Fabrics under tension look worse and feel worse.
For tops and dresses, look for extra length in the body — the bump lifts fabric at the front, turning a regular-length top into a crop by the third trimester. Pieces cut with additional length front or designed specifically for a growing belly will hold their shape better across trimesters.
The bust problem This is the area that most maternity sizing ignores. If your bust is increasing alongside your belly, you need tops with enough ease in the chest to accommodate both. Nursing bras and feeding-access tops are worth buying in the second trimester rather than waiting — your size won't be exactly what it'll be postpartum, but having the right support early makes a difference.
The honest advice When in doubt, go up a size. Maternity clothing with stretch is designed to accommodate a range. A piece that's slightly large at week 20 will fit better at week 30 than something that fit perfectly at week 20 and cuts in by week 28.
be imli's pieces are sized with a growing body in mind — stretch fabrics that move with you, overbelly fits as the default, and cuts designed with enough ease to work across trimesters. If you're unsure, the size guide is on each product page, and the team is reachable if you need help choosing.
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