Somewhere in the second trimester, sleep changes. You are told to sleep on your side, and you try, but your hips ache, your belly pulls, and you keep waking up flat on your back wondering how you got there.
This is normal. Below is why side sleeping gets harder as pregnancy goes on, five setup changes many people find helpful, and what to bring up with your OB or midwife. One note before we start: anything medical, including which side to sleep on and how concerned to be about waking up on your back, is a question for your provider, not a blog post.
Why does side sleeping get harder as pregnancy goes on?
Side sleeping is recommended by many providers in later pregnancy. For a lot of people it is also the least comfortable option by the time they are asked to do it. Here is why, trimester by trimester.
First trimester: fatigue, not position
Most people can still sleep however they like in the first twelve weeks. The problem is usually exhaustion, nausea, and getting up to use the bathroom. It is a good time to start practicing side sleeping, but there is no need to force it yet.
Second trimester: hip pressure and the first belly pull
As your weight increases and hormones loosen the ligaments around your pelvis, the hip you are lying on takes more load and the top hip drops forward. Your top knee slides toward the mattress, twisting your lower back. At the same time the belly has enough weight that, lying on your side, it pulls toward the bed and tugs on the ligaments that hold it.
Third trimester: the gap, the heat, and the roll
By now three things are happening at once. There is a gap between your lower back and the mattress that nothing fills, so the back muscles work all night. Your body runs warmer, and the extra padding of blankets and pillows traps heat. And when you finally fall asleep, you may roll onto your back, then wake up short of breath or lightheaded.
Five setup changes that many people find helpful
You do not need to change everything at once. Try one or two and see what helps.
1. Put a pillow between your knees
This is the single change that helps most people the most. A pillow between the knees keeps the top hip level with the bottom one, which stops the pelvis from twisting and takes strain off the lower back. It should be thick enough that your knees are roughly hip-width apart. A dedicated knee cushion stays in place better, but a folded bed pillow is fine to start.
2. Support the belly with a wedge
A small wedge tucked under the side of your belly takes the weight off the ligaments so it is not hanging toward the mattress. It does not need to be big. If a wedge feels like too much, a thin, firm pillow does the same job.
3. Fill the gap behind your back
A firm pillow or wedge behind your lower back does two things. It fills the space so your back muscles can rest, and it makes it harder to roll fully onto your back during the night. If you do roll, you tend to end up tilted rather than flat, which many people find more comfortable and less alarming to wake up in.
A full-length body pillow can handle steps one through three in one piece. The C-Shaped Support Pillow curves around the front of the body so you hold one end between your knees while the other supports your head, and you flip the whole thing over when you switch sides. You can compare shapes in our pregnancy and full body comfort collection.
4. Cool down the cover
Overheating is a real reason people give up on body pillows. Look for a cover made from a breathable fabric, and keep the room a few degrees cooler than you normally would. The Cooling Full Body Pregnancy Pillow was built with this in mind, with a cover that pulls heat away from the skin rather than holding it in. A lighter blanket and a fan also help.
5. Check your head pillow height
With a body pillow under you, your shoulders may sit higher than before. If your head pillow is now too low, your neck bends down and you wake up with a stiff neck on top of everything else. Adjust the head pillow so your nose stays in line with your chest. If heartburn or congestion is also a problem, raising your upper body slightly with a wedge such as the Elevation Wedge Pillow may help while keeping you on your side.
What to ask your provider
Bring your sleep questions to your OB or midwife rather than working them out alone. Useful things to ask: which side they recommend for you and from what week, what to do if you keep waking up on your back, whether the hip or back pain you are feeling is expected or worth a referral to a physical therapist, and whether anything about your pregnancy changes the general advice. If you have sudden or severe pain, dizziness that does not pass, or anything that worries you, call them. Do not wait for your next appointment.
Frequently asked questions
Which side should I sleep on?
Many providers suggest the left side in later pregnancy, but recommendations vary and depend on your situation. Ask your OB or midwife what they want you to do. Either side is generally considered better than flat on your back late in pregnancy.
What if I wake up on my back?
It happens to almost everyone. Roll back onto your side and go back to sleep. A pillow or wedge behind your back makes it less likely. If you are waking up on your back often and it worries you, mention it to your provider.
When should I start using a pregnancy pillow?
Whenever side sleeping starts to feel uncomfortable, which for many people is around 18 to 24 weeks. Starting earlier is fine.
Can I keep using the pillow after the baby arrives?
Yes. Many people use a body pillow for support while feeding, and the knee and back sections stay useful for side sleeping in general. A pillow with removable sections is easier to adapt once you no longer need the belly support.
Where to start
Start with a pillow between your knees tonight, even a spare bed pillow, and see how your hips feel in the morning. If it helps and you want something that covers knees, belly, and back at once, the Adjustable Pregnancy Body Pillow has sections you can move or remove, so it changes with you from the second trimester through the newborn months. It ships free within the US, is dispatched in 1 to 2 business days, and comes with 30-day returns and no restocking fee.