Expectant mothers have been advised for years that sleeping on the left side of their body during pregnancy is best for the baby. Sleeping on the back, called the supine position, was particularly discouraged. Failure to follow this recommendation came with warnings of increased risk of stillbirth, underweight newborns, and gestational hypertension in the mother.
However, recent research has cast doubt on the validity of these warnings. A large prospective study of over 8,000 pregnant women indicates that there is actually no correlation between sleep position and stillbirth or the other adverse events mentioned above. Let’s take a look at this new study and what it means, beginning with its importance.
Why Does Sleep Position During Pregnancy Matter?
The previous thought was sleep position affected the risk for adverse events because certain positions put pressure on different areas of the body. For example, sleeping on your back when pregnant, especially late in pregnancy, puts pressure on several vital organs. Conversely, sleeping on your left side, or left lateral position, may improve circulation and keep the uterus from compressing the liver, which is located on the right side of the abdomen.
So, if sleep position has no influence on the risk of adverse events, why not advise pregnant women to sleep on their left sides anyway – just to be safe? The answer is that, if all sleep positions are equal, women should feel free to choose the position most comfortable for them. Good quality sleep can be elusive during pregnancy due to changes in body size, stress and hormonal fluctuations. In fact, women often ask their OB-GYNs for sleep advice during their pregnancy care.
Additionally, in the event of a tragic occurrence such as a stillbirth, a woman may have unjustified feelings of guilt. She may incorrectly believe that her sleep position led to the stillbirth despite the evidence for this conclusion being outdated.
What’s New about This Study?
Sleep position recommendations were previously based largely on retrospective studies. These studies surveyed women who had experienced a stillbirth or other adverse event and asked them questions about their sleep position during pregnancy. This retrospective approach is not ideal due to a phenomenon called recall bias.
When people are questioned after a tragic or devastating event like a stillbirth, they tend to report anything they believe may be connected to the event, whether correct or not. Recall bias is often unconscious, but it can have a profound effect on survey studies that depend on respondents’ answers. Since there was no objective determination of the sleep positions of the women surveyed, the previous studies relied on the accuracy of the survey answers.
In this new study, the researchers used a prospective approach. In other words, they surveyed a large group of women about their sleeping positions early in their pregnancies. They then followed up with the women after their pregnancies to see if there was any correlation between non-left lateral sleep and adverse events. The researchers found no such correlation.
What’s the New Advice?
In science, it is not possible to absolutely prove a negative. We can say that this new study showed no correlation between non-left side sleep and adverse pregnancy events, but it cannot be stated with complete certainty that no such correlation exists. What medical authorities can now assert is that a strong link appears very unlikely, and pregnant women should typically not restrict themselves to left-sided sleep if that position is uncomfortable for them. The risks presented by not sleeping on the left side of your body during pregnancy are likely less severe than the risks of not getting adequate sleep.
Of course, if you have questions or concerns about these recommendations – or any pregnancy care topic – you should turn to your OB-GYN. They know your individual situation and are in the best position to offer advice tailored to you and your pregnancy.
About the Connecticut OBGYN Practice
Dr. John Garofalo, M.D., is a CT OBGYN based in Fairfield County, providing care for Norwalk, Darien, New Canaan, Weston, Rowayton and the surrounding areas. He has more than 20 years of practice and surgical experience covering many facets of obstetrics and gynecology.
Laury Berkwitt, APRN, is a nurse practitioner specializing in women’s health in Fairfield County, Connecticut. Women undergoing signs and symptoms of menopause can make an appointment with Laury for Hormone Replacement Therapy. Laury has a passion for providing quality women’s health care in a safe and comfortable manner by creating a trusting patient-practitioner relationship. She has been in practice for more than 10 years, caring for women of all ages.