What Size Pregnancy Pillow Do You Need?

The short answer

Step 1: your bed decides the shape

This is the step almost everyone skips, and it is the one that determines whether the pillow is still in use at 38 weeks. Measure before you compare shapes.

A 55 to 57 inch U is roughly 30 inches across at its widest, which is most of half a queen. That is the number people are surprised by, and it is the most common reason these pillows end up in a cupboard. We argue the shapes out in U-shaped versus C-shaped.

Step 2: your height decides the length

The thing that matters is whether your knees land on the pillow when your head is at the top of it. If they do not, the knee gap — the single most useful thing a pregnancy pillow does — is not happening.

A wedge has no length requirement, which is part of why it is the safe first purchase.

Step 3: firmness, which is not a size but behaves like one

A pillow that is the right size and too soft fails at the job anyway. The knee gap has to hold, and polyester fiber fill compresses under the weight of a leg within a couple of hours.

• Bead fill — firmest, adjustable, most expensive.
• Memory foam — holds height, runs warm, heavy.
• Polyester fiber — light, cheap, flattens. Fine for belly support, poor for the knee gap.

If you are choosing between two pillows of the same size, the firmer one is usually the better buy — see the hip-pain comparison, where fill drives the ranking.

The washing question, which affects your size choice

Worth thinking about before you buy, because it is a genuine annoyance with large pillows.

The cover must be removable. Treat a non-removable cover as a reason not to buy, because you will be sweating on this for months.

The pillow itself is usually spot-clean only. A 57-inch fiber-filled pillow takes days to dry properly, can clump if machine-washed, and may not fit in a domestic machine at all. Check the care label.

This is a quiet argument for smaller or modular designs: a wedge and a knee cushion both fit in a washing machine, and a U does not.

What to do if you are between sizes

Go smaller and add a second piece. A C plus a wedge costs about the same as a U, takes less bed, washes more easily, and lets you take the wedge away with you. A single large pillow is tidier; two smaller ones are more adaptable.

And if you are buying before about 24 weeks, buy small deliberately. A wedge now tells you whether belly support was what you needed, and if you later want something shaped you will buy it knowing which problem you actually have. See pregnancy pillow versus wedge.