Side sleeping is the safest and most comfortable position during your third trimester, and a few simple adjustments to your pillow setup, fluid timing, and bedtime routine can make a real difference in how well you rest. Most of the discomfort you’re feeling right now, from hip pain to heartburn to constant bathroom trips, has a practical workaround.
Why Side Sleeping Matters After 28 Weeks
As your uterus grows, it becomes heavy enough to compress major blood vessels when you lie flat on your back. Specifically, the weight of the uterus presses against the inferior vena cava, the large vein that returns blood from your lower body to your heart. This compression can reduce blood flow to the placenta and cause a drop in your blood pressure. A large analysis published in JAMA Network Open found that going to sleep on your back in late pregnancy was associated with a 2.6-fold increased risk of late stillbirth compared to side sleeping.
Rolling onto either side relieves this compression immediately. Left-side sleeping has traditionally been recommended because it keeps the uterus off the vena cava most effectively, but both sides are considered safe. An NIH-funded study that tracked sleep positions found no increased risk of stillbirth, low birth weight, or blood pressure disorders from right-side sleeping through 30 weeks. The key takeaway: avoid falling asleep on your back as your go-to position, but either side works.
What to Do If You Wake Up on Your Back
This happens to almost everyone, and it’s not a reason to panic. Your body gives you warning signals long before your baby is in any danger. You’d feel nauseated, dizzy, or breathless from the drop in blood pressure before oxygen delivery to your baby became a concern. If you wake up on your back, simply roll to your side and settle back in.
If it keeps happening, try tucking a pillow behind your back to prevent yourself from rolling over. You can also ask your partner to gently nudge you back to your side if they notice you’ve shifted during the night.
How to Set Up Your Pillows
The right pillow arrangement supports three areas that take the most strain in late pregnancy: your belly, your hips, and your lower back. The most effective setup for side sleeping is a pillow between your knees, another under your belly, and one behind your back. This keeps your pelvis aligned, prevents your top leg from pulling your spine into rotation, and stops you from rolling backward.
A full-length pregnancy pillow (C-shaped or U-shaped) can do all of this at once. With a C-shaped pillow, rest your head on one end, hug the curve against your chest and belly, and bend the other end between your knees. Your ankles should sit above and below the bottom of the pillow to keep them slightly elevated, which helps with swelling. Some people prefer the curve of the C against their back for support getting in and out of bed; others prefer it against their front for belly support. Experiment to see what feels best.
With a U-shaped pillow, you sleep inside the U with your head on the top curve and one arm of the pillow along your front, the other along your back. This gives you support on both sides so you can switch from left to right without rearranging everything.
Reducing Nighttime Bathroom Trips
Frequent urination at night is a normal part of pregnancy, and no medication is recommended for it during pregnancy. It resolves after delivery. But you can reduce how often it wakes you up by adjusting when and how much you drink.
Stop drinking fluids about two hours before bedtime. Between dinner and bed, take sips rather than full glasses of water. Make sure you’re getting plenty of fluids earlier in the day so you’re not making up for it at night. Cut out caffeine in the afternoon and evening entirely, since caffeine can increase both bladder activity and urine production on its own.
Keeping a short path to the bathroom also helps. Some people find that a dim nightlight in the hallway prevents them from fully waking up during trips, making it easier to fall back asleep. Pelvic floor exercises (Kegels) can also improve bladder control: aim for three sets of 8 to 12 slow contractions, holding each for 6 to 8 seconds, three or four times per week.
Managing Heartburn at Night
Acid reflux gets worse in the third trimester because your growing uterus pushes your stomach upward, and pregnancy hormones relax the valve between your esophagus and stomach. Lying flat makes it worse. Elevating your upper body at a 30- to 45-degree angle, raising your head about 6 to 12 inches, keeps stomach acid from traveling upward.
A wedge pillow placed under your regular pillow or upper back works well for this. Some wedge pillows are specifically designed for pregnancy, with cutouts or contours that accommodate a belly. If you don’t have a wedge, stacking two firm pillows can approximate the angle. Eating your last meal at least two to three hours before lying down also makes a significant difference.
Dealing With Restless Legs and Cramps
Restless legs syndrome, that uncomfortable crawling or tingling sensation that creates an overwhelming urge to move your legs, affects a significant number of pregnant people and tends to peak in the third trimester. The cause isn’t fully understood but likely involves low iron stores, folate levels, and hormonal changes.
If you’re experiencing restless legs, it’s worth having your iron levels checked. Oral iron supplementation is generally recommended during pregnancy if your ferritin (a measure of iron stores) is low. The typical approach is a ferrous sulfate tablet containing 65 mg of elemental iron, taken once or twice daily. Despite popular advice, there’s no solid evidence that magnesium supplements help with restless legs in pregnancy. Folate, which is already in most prenatal vitamins, may play a supportive role.
For leg cramps specifically, gentle stretching before bed can help. Flex your foot upward (toes toward your shin) when a cramp strikes rather than pointing your toes, which can make it worse. Staying well hydrated during the day and keeping your legs slightly elevated while you sleep also reduces cramping.
When Snoring Becomes a Concern
Some snoring in late pregnancy is normal as nasal tissues swell from increased blood volume. But loud, frequent snoring combined with extreme daytime sleepiness, morning headaches, or episodes where you seem to stop breathing could signal obstructive sleep apnea. This matters because sleep apnea in pregnancy is linked to roughly double the risk of preeclampsia and gestational diabetes, and a higher likelihood of preterm delivery.
If your partner notices that your snoring is unusually loud, that you gasp or choke during sleep, or if you feel exhausted despite spending enough hours in bed, bring it up with your provider. Sleep apnea in pregnancy is treatable and catching it can reduce the risk of serious complications.
Building a Sleep-Friendly Routine
Beyond position and pillows, a few habits make third-trimester sleep more manageable. Keep your bedroom cool; your body temperature runs higher during pregnancy, and a cooler room (around 65 to 68°F) supports deeper sleep. A consistent bedtime helps your body anticipate sleep, even when you know you’ll be up at least once or twice.
Light stretching or a warm (not hot) bath before bed can ease muscle tension and signal your body to wind down. If you can’t fall back asleep after 20 minutes, get up and do something quiet in dim light rather than lying in bed getting frustrated. The pressure to “sleep while you can” before the baby arrives is real, but stressing about sleep only makes it harder to get.