One of the challenges of pregnancy can be finding up-to-date guidance on the safety of certain exercise practices, as this field is constantly evolving with the emergence of new research. One example of this evolving guidance is the perspective on lying on your back (or supine) during pregnancy. This article will present the latest thinking on the supine position so that you can feel confident when making choices about your movements and activities.
First, it’s important to understand why lying flat on your back may be a problematic position for the mother and fetus before getting into some recommended modifications for prenatal exercises.
Why Can Lying On Your Back Be Problematic?
Traditionally, medical guidance has been to avoid the supine position during later pregnancy (second and third trimesters) because of the concern that one could develop Supine Hypotensive Syndrome (SHS). This condition is characterized by reduced blood and oxygen flow to the fetus when the weight of the belly compresses the primary artery that transports those nutrients. The symptoms of SHS include dizziness, nausea, sweating, increased heart rate and a reduction in blood pressure. These symptoms usually appear within 3-10 minutes of lying supine (4). However, “these are transient symptoms which resolve with maternal position change, such as leftward tilt (3).” In other words, if you feel these symptoms, no need to panic. Simply change your position and the symptoms should resolve.
Therefore, it appears that short periods on the back are safe and can be utilized, as tolerated. However, what about longer-term periods in supine? Does this mean you shouldn’t sleep on your back?
Is Sleeping in Supine Safe?
The growing body of research into this question appears to demonstrate that long periods of being in supine during late pregnancy can contribute to undesirable outcomes for the fetus. Reduced uterine blood flow is associated with fetal growth restriction, potentially resulting in lower birth weight (1), and can increase the risk of late term stillbirth after 28 weeks gestation (2).
Interestingly, the healthy fetus can shift into a quiet state when oxygen is restricted, requiring it to use less (6). However, it isn’t yet known how long this reduced oxygen state can be tolerated before the fetus experiences any long-term negative consequences.
Experts generally say that sleeping on your side is safest. Many experts recommend the left side to alleviate pressure on your liver (which is on your right side) from your growing uterus. In addition, lying on your left side may improve circulation to the heart to allow for better blood flow to the fetus, uterus, and kidneys. However, the research on this is inconclusive. Other experts say that blood flow is the same on either side. So, also see what feels most comfortable for you.
Given the evidence, it is wise to try to fall, and remain, asleep in a side-lying position. If it’s comfortable for you, most experts recommend lying on your left side to avoid liver compression and improve circulation. Another option is to sleep on your back, but with your trunk bolstered to a more vertical position, to allow better uterine blood flow. You may want to place a pillow underneath your knees in this position, like below.
Is Exercising in Supine Safe?
Since it has been established that those in the second and third trimesters should avoid long periods in supine, you may be wondering about the safety of supine exercises. While prenatal guidance from many international governing bodies recommends avoiding supine exercises after 16 weeks, research from Mottola et. al. (2019) points out that, “the recommendation for caution was primarily based on expert opinion rather than explicit scientific evidence (5).”
Since the evidence is inconclusive, it is our recommendation that you use your best judgment and let comfort be your guide. If you want to do some gentle stretches on your back, and don’t feel any of the SHS symptoms listed above, then go for it. In addition, movements like bridges, which involve consistently moving while being on your back, are generally fine as well. As long as you are not remaining still for several minutes, you should feel okay. However, if you do begin to feel uncomfortable, simply move to your side or raise your trunk to a more upright position. The symptoms should resolve right away.
Generally, being on your back for short periods of time should be fine — especially if you are on your back and moving (like a bridge) or performing a gentle stretch — but always let comfort be your guide.
Modifications for Common Supine Exercises
The good news is that it’s pretty easy to find an alternative to most traditional supine movements. For every movement on your back, think of the goal of that movement ) and see if you can determine a different movement to accomplish a similar goal. Here are a few suggestions for common supine moves.
Bridges are an excellent exercise during pregnancy because stronger glutes help to alleviate low back and pelvic pain. As mentioned above, standard bridges do not require a modification because you are on your back and moving. However, if for any reason, you feel uncomfortable, you can also perform these with your shoulders elevated using a chair or couch.
Supine Chest Press
Instead of lying flat on your back to do a chest press, one option is to use a bench and raise the back of the bench to perform it on an incline. Don’t have access to a bench? No problem. You can also add a bridge to the movement. This keeps you moving on your back, and also adds in some nice glute work.
Crunches and Leg Lifts
We actually recommend avoiding these movements once you develop a belly — not because of concerns about being on your back, but because of the excessive intra-abdominal pressure (IAP) they create. Learn more about IAP, and the importance of managing this carefully during pregnancy in this piece on Core Exercises to Avoid. Instead, movements like Bird Dog or an incline plank would be safer and more effective.
Every yoga class ends with this wonderful relaxation lying flat on your back. Even if you do not feel SHS symptoms from this position, it may just become increasingly uncomfortable as your pregnancy progresses. As an alternative, lie on your side — ideally your left side — with a blanket or pillow underneath your neck and between your legs to keep your body in alignment.
More Help Moving Safely Throughout Pregnancy
Looking for a prenatal exercise program that is challenging, yet safe, throughout pregnancy? Check out our Prenatal Self-Guided Training Programs. Select the best program for you based on how far along you are when starting. For more personalized coaching, consider working with an expert PROnatal Personal Trainer.
If you’re a fitness professional interested in learning more about safe and effective exercise during pregnancy and postpartum, explore our Pre/Postnatal Professional Education, including our signature course to become a Pre/Postnatal Performance Training Specialist.
- Anderson, N.H., Gordon, A., Li, M., Cronin, R.S., Thompson, J.M.D., Raynes-Greenow, C.H., Heazell, A.E.P., Stacey, T., Culling, V.M., Wilson, J., Askie, L.M., Mitchell, E.A., McCowan, L.M.E. (2019). Association of Supine Going-to-Sleep Position in Late Pregnancy With Reduced Birth Weight: A Secondary Analysis of an Individual Participant Data Meta-analysis. JAMA Network Open, 2(10).
- Heazell, A., Li, M., Budd, J., Thompson, J., Stacey, T., Cronin, R.S., Martin, B., Roberts, D., Mitchell, E.A., McCowan, L. (2018). Association between maternal sleep practices and late stillbirth – findings from a stillbirth case-control study. BJOG, 125(2):254-262.
- Kim, D. R., & Wang, E. (2014). Prevention of supine hypotensive syndrome in pregnant women treated with transcranial magnetic stimulation. Psychiatry research, 218(1-2), 247–248.
- Kinsella, S.M. & Lohmann, G. (1994). Supine hypotensive syndrome. Obstetrics and Gynecology. 83:774–88.
- Mottola, M.F., Nagpal, T.S., Bgeginski, R., Davenport, M.H., Poitras, V.J., Gray, C.E., Davies, G.A., Adamo, K.B., Slater, L.G., Barrowman, N., Barakat, R., Ruchat, S. (2019). Is supine exercise associated with adverse maternal and fetal outcomes? A systematic review. British Journal of Sports Medicine 53:82-89.