Pregnancy Compression Socks: When and How Long

The short answer

Which mmHg?

Firmer is not automatically better. A harder-to-wear sock is a sock in a drawer, and the compression you actually wear beats the compression you bought.

When to put them on, and why it matters

Before you get out of bed. This is the single most useful piece of practical advice on this page.

Compression works by supporting the vein walls so blood moves upward instead of pooling. Overnight, lying flat, your legs are at their least swollen. Put the socks on then and you are holding the leg at a smaller size all day. Put them on at 4pm, when your ankles have already swollen, and you are compressing a leg that has already filled — less comfortable, and less effective.

It also makes them dramatically easier to get on, which matters more than it sounds by the third trimester.

How long to keep them on

• Through the day is fine, and is the normal pattern. These are not a garment you need to ration.
• Take them off at night unless your provider has specifically told you to sleep in them. Lying down, your legs are not fighting gravity, so compression is not doing anything useful and can be uncomfortable.
• Take them off if anything feels wrong: numbness, pins and needles, pain, color change in your toes, or a mark or indentation at the top band.
• Wash them daily and have more than one pair. Elasticity is what makes them work, and sweat and body oils degrade it.
• Replace them every few months of daily wear. A stretched-out compression sock is just a sock.

Getting them on, which is the real obstacle

Nobody warns you that the hard part of compression socks is putting them on while eight months pregnant and unable to easily reach your own feet.

1. Before you get out of bed, for the reasons above.
2. Turn the sock inside out down to the heel, get your foot into the heel, then roll the leg section up rather than pulling it.
3. Rubber washing-up gloves give you grip. This is a genuinely transformative tip and costs almost nothing.
4. A sock aid or donning aid exists for exactly this problem and is cheap. Late in pregnancy, bending to your own feet is the actual obstacle rather than the sock.
5. Ask someone. Entirely reasonable, and faster.
6. Make sure they are not bunched or rolled. A folded-over top band creates a tight ring, which is the opposite of graduated compression and can make things worse.

Sizing: measure, do not guess

Compression socks are sized by ankle and calf circumference, not shoe size. Pregnancy swells your calf as well as your foot, which is why a sock that fits your foot can easily be too narrow through the leg.

Measure your calf at its widest point, in the morning, and check the size chart on the actual listing. If you are near a boundary, buy a wide-calf cut — a sock you can get on is worth more than a theoretically better fit you cannot.

Flying, and long journeys

Compression socks are among the standard suggestions for long journeys in pregnancy, along with moving your ankles, getting up and walking where you can, and staying hydrated. Pregnancy increases clot risk, and long periods of immobility add to it.

If you are flying, discuss it with your midwife or OB beforehand — they may have specific advice for your pregnancy, and some airlines want documentation later on anyway.

Ask before you start if…

• You are considering 20-30 mmHg or firmer
• You have diabetes, or any reduced sensation in your feet
• You have a circulatory or arterial condition
• You have any skin condition, open wound or infection on your legs
• You have a history of clots
• You have one leg noticeably more swollen than the other — that needs assessment first

That last one again: swelling in one leg only, especially with calf pain, warmth or redness, needs urgent assessment rather than a compression sock.