Finding a comfortable sleeping position in the third trimester can be difficult. Your bump is larger, your bladder fills quickly, and heartburn or pelvic pain may wake you. The goal is not to hold one rigid position all night. It is to start each sleep on your side and use support that helps your body relax.
What is the best sleeping position in the third trimester?
After 28 weeks, public health guidance recommends going to sleep on your side. Either the left or right side is acceptable. This advice applies when you first go to bed, return to sleep after waking, and take a daytime nap.
The NHS advises side sleeping after week 28 because going to sleep on your back has been associated with a higher risk of late stillbirth. A large individual-participant meta-analysis also found an independent association between a supine, or back, going-to-sleep position and late stillbirth. These studies show an association. They do not mean that briefly waking on your back has harmed your baby.
Is the left side better than the right side?
You can use either side. Good research has not shown that the left side is safer than the right for most pregnancies. The left side may feel more comfortable if you have heartburn, but comfort can vary from night to night.
Switching sides is normal. If one hip becomes sore, roll carefully to the other side. A pillow between your knees may reduce strain on your hips, lower back, and pelvis.
What if I wake up sleeping on my back?
Do not blame yourself or lose sleep over it. You cannot completely control your body while asleep. Turn onto either side and settle again. The position you choose when falling asleep is the main behavior addressed by the research.
If lying flat makes you dizzy, breathless, nauseated, or faint, move onto your side and contact your maternity team if the symptoms do not settle. Your clinician may also give different instructions because of surgery, an injury, severe pain, or another medical condition.
Can you sleep propped up?
A supported, side-leaning position can help with heartburn or shortness of breath. Use pillows or a wedge to raise your upper body while keeping your weight tilted to one side. Avoid creating an unstable pile of pillows that strains your neck or lets you slide flat onto your back.
Some people find a recliner more comfortable. Ask your maternity clinician for personal advice if pain, breathing problems, sleep apnea, or reflux keeps disrupting your sleep.
How to arrange pillows for side sleeping
- Between the knees: Keep the hips more level and reduce twisting through the lower back.
- Under the bump: Use a small pillow or wedge to support the weight of your abdomen.
- Behind the back: A pillow can provide reassurance and make rolling fully onto your back less likely.
- Under the upper body: Gentle elevation may help nighttime reflux.
You do not need a branded pregnancy pillow. Standard pillows can provide the same basic support. Choose an arrangement that keeps your neck neutral and does not make it harder to get out of bed safely.
Why back sleeping becomes a concern after 28 weeks
In late pregnancy, the uterus is heavier. When you lie flat on your back, its weight can press on major blood vessels in the abdomen. This may reduce the amount of blood returning to your heart and can affect blood flow to the placenta. Some people also feel dizzy, sweaty, nauseated, or short of breath when lying flat.
Research has linked going to sleep on the back after 28 weeks with a higher risk of late stillbirth compared with going to sleep on the side. The research asks about the position used to fall asleep because that is often the position held for the longest part of a sleep episode. It does not show that a short period on your back while you are awake or turning over causes harm.
This distinction matters. The practical action is to begin each sleep on your side. It is not to stay awake monitoring every movement.
Biomechanical & Hemodynamic Sleep Matrix (28+ Weeks)
The following clinical reference illustrates how maternal position directly affects venous return, cardiac output, and uteroplacental perfusion during the third trimester:
| Sleep Position | Vascular & Hemodynamic Impact | Placental Perfusion & Oxygenation | Clinical Recommendation | Ergonomic Strategy |
|---|---|---|---|---|
| Left Lateral (Left Side) | Completely decompresses the inferior vena cava (IVC) and descending abdominal aorta; maximizes cardiac preload. | Optimal; highest rates of uterine blood flow and fetal oxygen delivery. | Gold Standard: Highly recommended as primary falling-asleep posture. | Place a medium pillow between knees and a wedge beneath the abdomen to relieve pelvic torsion. |
| Right Lateral (Right Side) | Minor IVC displacement; large international cohort studies show no statistically significant difference in stillbirth rates compared to left side. | Excellent; highly protective and completely relieves supine compression. | Safe & Recommended: Ideal alternate position to prevent hip pressure ulcers and lateral soreness. | Alternate between left and right side throughout the night as comfort dictates. |
| Supine (Flat on Back) | Gravid uterus compresses IVC and aorta against spine; can cause Supine Hypotensive Syndrome (maternal dizziness, pallor, hypotension). | Can reduce uterine blood flow and placental perfusion by up to 25% during prolonged periods. | Avoid After 28 Weeks: Do not intentionally fall asleep flat on your back. | If you wake on your back, gently roll to either side. Place a support pillow behind your back to prevent accidental rolling. |
| Semi-Recumbent / 30° Wedge Tilt | Upper torso elevation decreases intra-abdominal pressure against the diaphragm and lower esophageal sphincter. | Maintains patent venous return when hips remain tilted at least 15–30 degrees off horizontal. | Safe Alternative: Excellent for severe GERD, heartburn, or third-trimester orthopnea. | Use a firm foam bed wedge under head and torso, with a lateral pillow roll under one hip. |
Can you sleep on your stomach in the third trimester?
Sleeping on your stomach is not usually harmful in early pregnancy, but it becomes uncomfortable or physically difficult as the bump grows. By the third trimester, most people cannot settle fully on the abdomen.
A partly forward side position may still feel comfortable when pillows support the upper leg and bump. Make sure you can breathe freely and are not twisting your lower back. If you wake in an unusual position, move to your side without panic.
Every bump develops differently. If you are earlier in pregnancy and wondering when visible changes usually begin, see our guide to when pregnancy starts showing.
How to turn over with less strain
Rolling can become one of the hardest parts of sleep, especially with pelvic pain. Bend the knees slightly, keep them together, and move the shoulders and hips as one unit. Use your arms against the mattress for support rather than pulling through the abdomen.
To get out of bed, roll onto your side, move both legs over the edge, and push up with your arms. Pause while sitting before standing if you feel lightheaded. A stable bed rail may help some people, but it should be designed for the bed and installed safely so there is no entrapment gap.
Ask a physiotherapist or maternity clinician for a personal technique if you have severe pelvic girdle pain, a recent injury, restricted movement, or a planned recovery from surgery.
Sleeping with pelvic girdle or hip pain
Side sleeping may feel difficult when you have pelvic girdle pain. Keep your knees together when rolling, place a pillow between your legs, and avoid letting the top leg fall far forward. Sit on the edge of the bed before standing instead of twisting quickly.
Tell your midwife or obstetric clinician if pain affects walking, stairs, sleep, or daily movement. Physiotherapy and individualized support may help. Severe or sudden pain should not be assumed to be a normal sleep problem.
Side sleeping with heartburn
Heartburn often becomes more noticeable late in pregnancy. The NHS suggests raising the head and shoulders in bed and notes that the left side may help. A wedge under the upper body can be more stable than several loose pillows.
Try not to eat a large meal close to bedtime. Smaller meals, avoiding a personal trigger food, and staying upright after eating may help. Ask a pharmacist, midwife, or doctor which antacid or other treatment is suitable in pregnancy, particularly if you take other medicines.
Seek medical advice for severe chest pain, trouble swallowing, vomiting blood, black stools, or symptoms that feel different from usual heartburn.
Leg cramps and restless legs at night
Leg cramps can wake you suddenly. Gently flexing the foot upward, stretching the calf, and standing carefully may help. Keep the floor clear and use a light so you do not fall when getting out of bed.
Restless legs feels more like an uncomfortable urge to move the legs when resting. It can interfere with falling asleep and may be associated with low iron in some people. Do not start a high-dose iron supplement without advice, because too much iron can cause problems and the correct treatment depends on assessment.
Call for urgent help if one leg becomes newly swollen, red, warm, or painful, especially with chest pain or sudden shortness of breath. A blood clot requires prompt medical evaluation.
Frequent urination and safer nighttime movement
Needing the bathroom more often is common in the third trimester. Keep a clear path from the bed, remove loose rugs, and use a dim night light. Sit on the side of the bed for a moment before standing if you tend to feel dizzy.
Continue to drink enough during the day. Cutting fluids too aggressively can contribute to dehydration. It may help to reduce large drinks immediately before bed while still meeting your normal needs.
Tell a clinician about burning urine, fever, lower abdominal pain, blood in the urine, or a sudden change in frequency. These symptoms may need testing for a urinary infection.
Naps follow the same side-sleep guidance
The advice after 28 weeks applies to daytime naps as well as nighttime sleep. Settle on either side even if you expect to sleep for only a short time. If you nap in a recliner, make sure you are securely supported to one side rather than lying flat on your back.
A short nap can help after a broken night, but long or late naps may make it harder to sleep at bedtime. There is no single schedule that works for everyone. Focus on safety and the amount of rest your body needs.
Do sleep-position pillows prevent rolling?
A pillow can provide support, but no pillow guarantees that you will not move. The goal is comfort and a side-sleep starting position, not physical restraint. Avoid products that trap you in one position, compress your abdomen, affect breathing, or make it difficult to get out of bed.
You can try a small wedge behind your back, a pillow between your knees, and another under the bump. A full-length pillow may combine these functions. Check that the arrangement does not push your neck forward or create a fall hazard.
There is no need to buy a monitor that alerts you whenever you roll. If you naturally wake on your back, turn to the side and go back to sleep.
Sleep medicines, antihistamines, and herbal remedies
Do not assume that an over-the-counter sleep aid, antihistamine, melatonin product, tea, or herbal supplement is suitable during pregnancy. Products can contain several ingredients, doses vary, and "natural" does not mean proven safe.
Ask a doctor, midwife, or pharmacist before using a sleep product. Tell them about all medicines and supplements you take. If anxiety, low mood, pain, reflux, itching, or breathing symptoms are keeping you awake, treating the cause may be more useful than adding a sedating product.
Never combine sleep medicines with alcohol, and do not drive if a medicine makes you drowsy.
Baby movements and sleep
Your baby has periods of activity and sleep. The exact pattern is individual, and movement may feel different as space becomes tighter. However, you should continue to feel movement right up to labor.
Contact your maternity unit immediately if your baby is moving less than usual, you cannot feel movement, or the normal pattern changes. Do not wait until morning, go to sleep to see whether it improves, or use a home Doppler or phone app for reassurance. These devices cannot replace assessment.
Your maternity team can tell you the right local number to call. Keep it saved before you need it.
When poor sleep needs medical attention
Occasional broken sleep is common late in pregnancy. Contact your maternity team if you have loud snoring with choking or gasping, repeated breathing pauses, severe daytime sleepiness, chest pain, persistent shortness of breath, severe headache, vision changes, sudden swelling, bleeding, leaking fluid, regular painful contractions, or reduced fetal movement.
Changes in your baby's usual movement pattern need prompt assessment. Do not wait for the next day or rely on cold drinks, food, or a home device to reassure yourself.
A simple bedtime routine
- Use the bathroom and place water within easy reach.
- Settle on either side with a pillow between your knees.
- Support your bump or upper body if needed.
- Keep the path to the bathroom clear and use a night light.
- If you wake on your back, roll onto your side without worrying.
Frequently asked questions
Is it safe to sleep on my right side in the third trimester?
Yes. NHS guidance says either the left or right side is suitable for going to sleep after 28 weeks. Use the side that is more comfortable and switch when a hip becomes sore.
What should I do if I spent the night on my back?
Do not panic. The advice focuses on the position used to go to sleep. When you notice you are on your back, turn onto either side. Contact your maternity team if you feel unwell or have concerns about your baby's movements.
Can I lie on my back for an examination or exercise?
A short, supervised position while awake is different from choosing a sleep position. Tell the clinician or instructor if you feel dizzy, nauseated, breathless, or uncomfortable. Follow individual advice for your pregnancy and activity.
Does sleeping on the left side improve blood flow?
The left side may feel better for heartburn and is often recommended for comfort, but current public guidance allows either side. You do not need to force yourself to stay on the left all night.
When should I seek help for insomnia?
Speak with a clinician when poor sleep is persistent, affects daytime safety, or comes with low mood, severe anxiety, loud snoring, gasping, breathing pauses, pain, intense itching, or other concerning symptoms.
Sources
Related reading: review the stage transition in when the third trimester starts.
- NHS: pregnancy sleep-position guidance after 28 weeks
- Cronin et al.: individual participant data meta-analysis of sleep position and late stillbirth
- NCBI Bookshelf: evidence review of maternal sleep position
- Tommy's: clinically reviewed sleep-position questions and answers
- NHS: tiredness, sleep problems, and side sleeping in pregnancy
- Royal College of Obstetricians and Gynaecologists: baby movements in pregnancy
- NHS: managing heartburn during pregnancy
