Our pregnant patient Robin asked us the following question,
“One question that I know has circulated through the office is the risk of sleeping on your back during pregnancy and whether it truly causes the fetus to lose blood flow.”
The position that you sleep in during pregnancy matters in a few circumstances. These include the trimester you are currently in, your position of preference when sleeping and the quality of your sleep.
The general recommendation of many obstetricians is that sleep position in your first trimester has no impact on your health or your baby’s. The cause for concern is that later in pregnancy (during your second and third trimester) the weight of your uterus grows with the increase in size of the baby. This growth in the weight and size of the uterus can put pressure on a large blood vessel known as the inferior vena cava (a large vein that returns blood flow to the heart) or abdominal aorta (a large artery that moves blood from your heart to your lower body) when you sleep on your back. This pressure can interfere with the blood flow and nutrients moving to the placenta (and the baby) if you lay on your back for an extended period of time.
The Canadian Society for Exercise Physiology and the Society of Obstetricians and Gynaecologists of Canada recommends that past 16 weeks exercise normally completed in the supine position (on your back) should be altered or avoided.
Sleeping on your back during pregnancy is a serious concern if you have high blood pressure and often your Family Doctor, Midwife or OB/GYN will advise you to sleep on your side. If when lying down on your back you experience syncope or light headedness you should make an appointment with your healthcare provider to have your blood pressure checked and review recommended sleeping positions.
Women should try to start out on their left side but if you wake up during the night on your back do not be alarmed. There should be no serious adverse effects to you or the baby. You can switch positions and go back to sleep on your side once you are comfortable.
Women can choose to start training themselves early in pregnancy to sleep on their side by using a pillow between their legs, under their hip or placing body pillows behind them in bed to encourage a specific position for comfortable sleep.
Visit the My Pregnancy Tool page for more resources on your pregnancy.