Maternity Sizing Conventions by Country
Maternity wear typically uses your pre-pregnancy size. Stretch panels and adjustable waistbands accommodate growth. Some brands explicitly label maternity (US M, EU 38M, UK 12M).
The Chart
| Region | Maternity Sizing | Notes |
|---|---|---|
| US | Pre-pregnancy size | Old Navy Maternity, Pea in the Pod, Motherhood — true to pre-preg size |
| UK | Pre-pregnancy size | ASOS Maternity, JoJo Maman Bébé, Boohoo Maternity — true to pre-preg size |
| EU | Pre-pregnancy or +1 | H&M Mama, Mango Mama, Zara Maternity — sometimes +1 size for late trimester |
| JP | Stretch sizing M-LL | More fluid sizing without strict trimester maps |
| Universal | Trimester-specific | Some brands use 'Bump 1/2/3' for first/second/third trimester |
Notes
Most modern maternity brands use pre-pregnancy size with stretch built in. Old-school approach (size up by trimester) is becoming rare. Nursing tops and dresses also fall under maternity sizing — typically labeled the same as the pre-pregnancy size + nursing access feature.
FAQs
Should I size up for late pregnancy?
Most modern stretch maternity wear handles all 3 trimesters in pre-preg size. Only size up if specific items (jeans, structured dresses) feel restrictive in third trimester.
Maternity vs nursing wear?
Maternity has belly-room growth. Nursing has chest access (drop cups, side panels, button fronts). Many tops are dual-labeled 'Maternity & Nursing'.
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