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Statement From the Division of Maternal-Fetal Medicine Regarding Maternal Sleep Practices and Late Stillbirth

Supine sleep

Pregnant women can rest easy about sleep position during pregnancy.

In October, a research paper, titled “Association between maternal sleep practices and late stillbirth – findings from a stillbirth case-control study,” was published in the British Journal of Obstetrics & Gynecology. Since that time, a flurry of news articles, Facebook posts and tweets have warned women that sleeping on their back during pregnancy (e.g., supine sleep) may kill their baby, while sleeping on the side can reduce their risk of stillbirth by 50 percent. In an effort to provide the most accurate and timely information to expectant mothers, the Division of Maternal-Fetal Medicine at University of Utah Health has reviewed this study in great detail and believes that the conclusions may not be justified.

The Division of Maternal-Fetal Medicine has issued the following commentary on the study:

  • Although the authors of the research paper state that they have confirmed the association between expectant mothers sleeping on their backs and stillbirth, we believe their research methods have three significant flaws: The study design is significantly limited by the potential for recall bias, where women who experienced stillbirth report remembering something more frequently than women with healthy, ongoing pregnancies. Recall bias is strongly influenced by human nature to link a bad outcome (like stillbirth) to something we may have done “wrong” to cause it. The authors of the British study asked women with ongoing healthy pregnancies how they went to sleep the night before the interview, but they asked women who had stillbirths how they went to sleep an average of 25 days after the stillbirth. The women with stillbirths were therefore less likely to accurately report their sleep position. In addition, women who have something bad happen to them in pregnancy often search for answers. They may turn to the internet and see speculation that supine sleep might be associated with stillbirth. Therefore, women with a stillbirth may have also been more likely to report supine sleep.
  • The authors present statistics that were calculated in such a way that overestimates the risk of stillbirth associated with supine sleep.
  • This study and previous studies may mistakenly conclude supine sleep is the problem, when in fact, supine sleep may simply be a marker for the real problemObstructive sleep apnea, which occurs when throat muscles relax and block your airway during sleep, worsens when people sleep on their backs. Obstructive sleep apnea is known to cause episodes of low oxygen and can be harmful to a woman’s heart, lungs and circulation. Obstructive sleep apnea might therefore increase the risk of pregnancy complications including stillbirth. If supine sleep is only a marker for the real problem of sleep apnea, then changing sleep position would not solve the problem, but rather screening for and treating sleep apnea would be the solution.

Stillbirth is a tragedy that is devastating for families. As such, we wholeheartedly support efforts to find causes of stillbirth and efforts to reduce or eliminate stillbirths. It is quite tempting to adopt the results of the sleep studies in well-intended hopes of reducing stillbirths. This is especially true given the seemingly “low risk” of sleeping on the side during pregnancy. However, these recommendations have the potential to cause harm by increasing anxiety, stress and guilt over something that may not be possible to control.  

Based on the available data, we cannot conclude that sleeping on your back during pregnancy causes stillbirth. Until more compelling data are available, we should focus on modifying other known risk factors for stillbirth, such as smoking and obesity. Perhaps more importantly, we do not want women to feel guilt or anxiety regarding sleep position, which can be very difficult to change and maintain.

Good sleep in pregnancy is important for a healthy mom and a healthy baby. In our opinion, worrying about sleep position is more harmful than helpful.

Rest easy and sleep well pregnant women.