Baby sizing is measured in months, but babies are not. A label is a rough guide to length and weight, and length is the one that matters.

Read weight first, months second

0–3M usually covers 3.5 to 6 kg. Most newborns arrive inside that range, and grow out of it around eight weeks. If you only buy one size before birth, buy this one — and buy fewer pieces than you think you need.

Zips beat buttons at 3am

A two-way zip sleepsuit opens from the bottom for a nappy change without undressing the whole baby. Ten poppers, in the dark, with one hand, is a different experience. Buy at least two zip pieces before you buy a tenth popper piece.

Everything you buy in newborn size gets about six weeks of use. Spend on the four pieces you will wash twice a week, not the ten you will photograph once.

If in doubt, size up

• Sleeves and legs can be rolled — a tight neckline cannot be fixed.
• Cotton shrinks slightly on the first wash. Assume half a size.
• For mom wear, order one size above pre-pregnancy for the first eight weeks.

Easy first buys

• Organic Cotton Bodysuit
• Sleepsuit with Zip
• Newborn Cap & Mittens Set

Newborn skin is thinner than adult skin, so what stays in the fabric matters more than what the detergent bottle promises. The good news: the simplest routine is also the gentlest.

Wash once before the first wear

New cotton carries finishing residue from the mill. One wash before the first wear removes it and takes care of the small shrink at the same time — which is why we suggest not sizing down.

Four rules

• Mild, fragrance-free detergent. Half the dose you would use for your own clothes.
• Skip fabric softener. It coats the fibres and reduces how much a muslin absorbs.
• Wash at 30–40°C. Hot water sets stains and hardens cotton.
• Dry in shade, not direct sun, and pull the piece back into shape while damp.

Softness is not something you add with a softener. It is what cotton does naturally if you stop coating it.

Stains, quickly

Rinse in cold water straight away — never hot. For milk and the usual newborn stains, a soak in cold water with a little detergent for thirty minutes does more than any scrubbing. Sunlight fades the last shadow of a stain on white cotton, once the stain itself is gone.

Cotton that washes well

• Organic Cotton Bodysuit
• Muslin Swaddle (2 Pack)
• Knitted Blanket