Pregnancy Life: What to Do and What to Avoid

Author: Li Hui
Publisher:
Publish Date: 2006-11-01
Features: What Sleep Position is Best for Pregnant Women
Everyone has different sleeping positions, known as "sleeping posture" or "sleeping style." A good sleeping posture can ensure sound sleep and adequate rest. As the ancient saying goes, "Stand like a pine, sit like a bell, sleep like an arch," showing that people have long recognized the importance of sleep posture since ancient times.
The best sleeping position for most people is on their right side. This is because the heart is located on the left side in a normal person, and lying on the right side reduces pressure on the heart.
After pregnancy, a woman's body (burden) increases, making her more prone to fatigue. She needs sufficient sleep and rest. In addition to at least 8 hours of sleep at night, it is advisable to lie down for about 1 hour during the day. Moreover, both sleep and rest require proper posture. In the early stages of pregnancy, lying down and sleeping in any position is acceptable as long as it feels comfortable. However, after the 12th week of pregnancy, lying on her back is not recommended, and she must sleep on her side, preferably on her left side.
This is because as the pregnancy progresses, the uterus expands continuously. By full-term pregnancy, the uterine cavity's volume increases nearly 10 times compared to a non-pregnant state, occupying almost the entire abdomen and compressing nearby organs. In the later stages of pregnancy, about 80% of the uterus rotates to the right, putting tension on the ligaments and mesenteries that support its normal position. If the blood vessels in the mesentery, which supply nutrients to the uterus, are stretched, it can affect fetal blood supply, leading to chronic fetal hypoxia. In severe cases, it may cause fetal distress or even death.
Some pregnant women may avoid sleeping on their side out of fear of compressing the fetus and choose to lie on their back. Research shows that prolonged lying on the back can lead to many adverse effects. When a pregnant woman lies on her back, the enlarged uterus not only compresses the superior vena cava in front of the spine but also presses against the abdominal aorta, which runs parallel to the inferior vena cava. Compression of the abdominal aorta reduces blood pressure in the uterine arteries, subsequently affecting uterine-placental blood flow. Insufficient blood supply to the uterus impairs the placenta's normal function, hindering fetal growth and development inside the womb.
At the same time, compression of the inferior vena cava obstructs blood (), reducing cardiac output and, consequently, fetal blood supply. The reduced cardiac output in the pregnant woman may cause symptoms such as chest tightness, shortness of breath, and varicose veins in the lower limbs. Due to the compression of blood vessels, renal blood flow decreases, leading to increased renin, angiotensin, and aldosterone, which may result in edema, reduced urine output, and pregnancy-induced hypertension syndrome.
Therefore, pregnant women are advised to sleep on their left side during pregnancy.