Compression in pregnancy: lighter legs for nine months
Updated 2 September 2026 · 6 min read
Pregnancy raises blood volume by roughly half, hormones relax vein walls, and the growing uterus presses on the veins returning blood from the legs — swelling and heaviness are the normal result. Class I compression (15–21 mmHg), worn daily from the first symptoms, is the standard preventive answer; class II only when a doctor diagnoses varicose veins. Sudden, painful or one-sided swelling is a medical matter, not a hosiery matter.
Why pregnancy legs feel heavy
Three changes stack up: blood volume grows by around 40–50 %, progesterone softens and widens vein walls, and from the second trimester the uterus increasingly presses on the pelvic veins that drain the legs. Valves that comfortably managed the old traffic now let blood pool — evening heaviness, visible veins and ankle swelling follow, most often from the second trimester on.
What compression does — and which class
Graduated compression narrows the widened veins from outside, helps the valves close properly again and pushes tissue fluid back into circulation. For the common, undiagnosed heaviness and swelling of pregnancy, class I (15–21 mmHg) worn through the day is the usual choice — comfortable enough for daily wear, which is the whole point.
If varicose veins are diagnosed during pregnancy, class II (23–32 mmHg) may be recommended by your doctor or phlebologist — follow their guidance on class and length.
Choosing a silhouette with a bump
Thigh-highs are the pregnancy favourite: full leg coverage with no waistband to negotiate with a growing belly. Knee-highs cover the most common swelling zone and are easiest of all. Classic pantyhose work well in early pregnancy; later, most women find a stay-up band kinder than anything at the waist. Sizing stays honest throughout — ankle and calf measurements change far less in pregnancy than the silhouette does.
When it is a doctor's matter
Swelling that arrives suddenly, is painful, clearly one-sided, or comes with headache and visual disturbance is not ordinary pregnancy swelling — it can signal thrombosis or pre-eclampsia and belongs to a doctor immediately. Compression hosiery is prevention and comfort, never a way to wait out a warning sign.
Frequently asked
Is compression safe throughout pregnancy?
Yes — it is an external, certified medical device with no systemic effect, and it is routinely recommended in pregnancy. The standard contraindications (arterial disease, neuropathy, acute thrombosis, broken skin) apply as always; when in doubt, ask your midwife or doctor.
When should I start wearing it?
With the first heaviness or visible swelling — for many women early in the second trimester. Waiting for veins to become visible first gives up the easiest prevention window.
And after the birth?
Vein walls stay hormone-softened for weeks after delivery, so many women continue class I for about six weeks postpartum, especially after a caesarean or with varicose veins that appeared in pregnancy. Your doctor may advise otherwise for your case.
