One leg swelling in pregnancy: when to get help

Pregnancy can cause fluid to collect around the ankles, often on both sides and more noticeably after standing. Swelling confined to one leg is different and can signal reduced blood flow, including a deep-vein clot. A clot may cause calf or thigh pain, warmth, redness, tightness, or a difference in leg size, but symptoms can vary. One leg swelling is not a diagnosis, so a clinician may need to examine you and arrange testing.

Contact your maternity service or doctor promptly and describe the side affected, the onset, pain, colour change, warmth, and any recent immobility or travel. Keep activity gentle and avoid tight clothing around the leg. Do not rub or massage the area, and do not take blood-thinning or anti-inflammatory medicine unless prescribed for you. Follow the assessment plan even if the swelling improves.

Call emergency services immediately for sudden breathlessness, chest pain, coughing blood, fainting, or a fast worsening illness with one-leg swelling. Seek urgent maternity advice for a severe headache, visual changes, upper abdominal pain, or sudden swelling of the face and hands, which can be warning signs of pre-eclampsia.

Ask whether you need same-day examination, blood-pressure measurement, or leg imaging; which symptoms should send you to emergency care; and which movements are safe until the cause is clear.