Large red patches appear on the thigh of a pregnant woman

Generally, large red marks on a pregnant woman's thighs may be related to poor blood circulation, stretch marks, skin allergies, eczema, purpura, or other causes, and targeted treatments can be applied accordingly. It is recommended to seek medical evaluation and follow the doctor’s advice for appropriate management. Specific causes are as follows:

1. Poor Blood Circulation

Due to uterine expansion and fetal growth, pregnant women may experience impaired blood circulation. This change can slow blood flow in the thigh area, leading to localized circulatory problems. Poor circulation may cause uniform redness on the skin of the thighs, possibly accompanied by mild numbness. Pregnant women should avoid prolonged sitting and may improve circulation through massage and warm compresses.

2. Stretch Marks

During pregnancy, rapid skin stretching combined with hormonal changes may reduce skin elasticity, resulting in dryness and cracks—commonly known as stretch marks. These typically appear as red or purplish-red streaks and gradually fade over time. This is usually a normal physiological change and does not require excessive concern.

3. Skin Allergy

A pregnant woman’s immune system may become more sensitive during pregnancy, causing allergic reactions to substances that previously did not trigger allergies. Skin allergies may result in red patches on the thighs, often accompanied by itching. Common allergens include food, medications, and environmental factors. Symptoms may be relieved under medical guidance using medications such as cetirizine hydrochloride oral solution, loratadine tablets, or promethazine hydrochloride tablets.

4. Eczema

Hormonal fluctuations and immune system adjustments during pregnancy may make women more prone to eczema. Eczema is a skin condition commonly presenting as localized redness, rashes, and itching, which may spread to the thighs. As directed by a physician, topical treatments such as prednisone acetate cream, Binghuang Fule ointment, or Chushi Zhiyang ointment may help alleviate symptoms.

5. Purpura

Purpura may occur during pregnancy due to inflammation of vascular endothelial cells, leading to bleeding and bruising. It typically presents as purplish-red spots or patches on the skin. When appearing on the thighs, purpura may be accompanied by pain, and the lesions may change color over time—from red to purple—before gradually fading. Treatment may include vitamin C tablets, calcium gluconate tablets, or methylprednisolone tablets, as recommended by a doctor.

In daily life, pregnant women should ensure adequate rest and maintain a balanced diet, which supports both maternal health and fetal development.