What causes swollen feet during pregnancy?

Many pregnant women experience swollen feet during the second trimester. This is actually caused by the uterus compressing some nerves during pregnancy. Swollen feet during pregnancy is a normal phenomenon that many expectant mothers will experience. If you find your feet swollen during pregnancy, you should take measures to reduce the swelling in time. There should be some ways to reduce swelling in the feet. But what exactly causes swollen feet during pregnancy? Let’s take a look at it together.

Most pregnant women will experience swelling of their hands and feet sooner or later during pregnancy, which we will call pregnancy edema.

Edema during pregnancy is caused by the fluid components in the blood vessels leaking out of the blood vessels and accumulating in the tissue spaces. Generally speaking, edema during pregnancy is more likely to occur after the 28th week of pregnancy. Because the expectant mother's uterus has grown to a certain size at this time, it may compress the venous return. Therefore, pregnant women with poor venous return are more likely to experience lower limb edema at this stage.

In addition, during pregnancy, the hormones secreted by the placenta and the aldosterone secreted by the adrenal glands increase, causing sodium and water retention in the body; water accumulates in the body and urine volume decreases accordingly; some expectant mothers also have severe anemia, low plasma protein, and water seeps from the blood vessels into the surrounding tissue spaces, etc.

Cause

The main reason for swelling of the hands and feet is that the enlarged uterus during pregnancy compresses the veins, causing obstruction of venous return.

Causes of lower limb edema during pregnancy include:

1. After pregnancy, blood volume begins to increase gradually from 6 weeks, reaches a peak at 34 weeks, and remains at this level until two weeks after delivery, when it returns to pre-pregnancy levels. Blood volume can increase by about 40% compared to the non-pregnant period, so as blood volume increases, interstitial fluid will also increase.

2. Because when blood increases, the increase in plasma is greater than the increase in blood cells, etc., the blood components will be relatively diluted, and the relative concentration of plasma albumin will be lower than that in the non-pregnant period. Plasma albumin is the main component that maintains plasma osmotic pressure. Plasma osmolality is lower during pregnancy than during non-pregnancy. This makes it easy for water in the blood to penetrate into the interstitial fluid, causing lower limb edema.

3. After pregnancy, the uterus enlarges, which increases the pressure in the pelvis, thereby affecting the venous blood flow in the lower limbs. This is also one of the important reasons for lower limb edema. If the swelling during pregnancy is relieved after rest or sleep, it is physiological and there is no need to worry.