“We do know that short periods of time ― even if you were on your back for an hour or two ― probably do no harm to your child,” she says.
Pregnancy-Safe Alternatives
Back sleeping is no longer safe after 28 weeks gestation, but there are a few other comfortable positions for you to safely doze in.
For the average healthy, fit pregnant female you CAN lay on your back for short periods of time here and there. Try keeping it to no longer then 5-10 minutes at a time. Your body will tell you if it's time to get up. You may feel nauseous, dizzy, etc.
If you normally sleep on your back, it's safe to continue doing so during the first months of pregnancy. But from 28 weeks, it's safer for your baby if you sleep on your side - whichever side you prefer. Don't worry if you wake up on your back, just roll on to your side.
In the second and third trimesters, lying on your back may compress a major blood vessel that takes blood to your uterus, making you feel dizzy and possibly reducing blood flow to your fetus. Sleeping on your side during your second and third trimesters may be best. Keep one or both knees bent.
Many physicians advise pregnant women to sleep on their left side. Previous studies have linked back and right-side sleeping with a higher risk of stillbirth, reduced fetal growth, low birth weight, and preeclampsia, a life-threatening high blood pressure disorder that affects the mother.
While it's touted as one of the best sleep positions for posture, sleeping on your back while pregnant is largely considered a no-no. Between 15 and 20 weeks gestation, the uterus starts becoming large enough to interfere with blood flow when you sleep on your back, as it can compress the IVC.
The best advice if you're expecting
After 20 weeks of pregnancy, try not to spend the entire night on your back, Dr. Zanotti advises. She suggests putting a pillow between your back and the mattress as insurance. That way, even if you do roll over, you're on a bit of a tilt.
From 28 weeks until your baby is born, be sure to sleep on your side. Whether you are taking a quick nap on the couch or going to bed at night, sleeping on your side is best. Lying on your back puts pressure on major blood vessels.
Even in your third trimester of pregnancy, bending is still considered safe for your baby. You'll probably find it becomes increasingly difficult for you, though, if not impossible. Apart from your extra body weight, the size of your belly is increasing.
In general, pregnant women should try not to lie flat on their back or directly on their stomach.
The research says that sleeping on your back is safe through your first trimester, which is just ending at 12 weeks. After 12 weeks, sleep on your side. Your left side or right side works just fine. But don't panic if you wake up in the middle of the night and you're on your back—just turn over to your side.
Stomach sleeping may be fine for the first part of the second trimester, until the growing baby bump makes this position uncomfortable. Starting around week 16, you should try to avoid sleeping on your back.
Pregnant women may find relief by snoozing with a pregnancy pillow or a pillow between their legs. A huggable pillow to wrap the arms and legs around can help release tension on the legs, knees, and lower back.
When lying on your back, that added weight can put pressure on your inferior vena cava, a major vein leading back to your heart. That has the potential to partially disrupt blood flow, and that's why it's advised to avoid lying on your back for extended periods of time.
Though it's unlikely to harm your baby, you'll likely find it too uncomfortable by the end of the first trimester — or potentially earlier. According to a report published by The Lancet, it's safest for you and your baby to sleep on your side by the 28-week mark, as it helps you both get the blood flow you need.
Some moms report that a short burst of exercise (like jogging in place) is enough to wake up their baby in the womb. Shine a flashlight on your tummy. Towards the middle of the second trimester, your baby may be able to tell the difference between light and dark; a moving light source may interest them.
Your 12 weeks pregnant belly
At 12 weeks, your baby bump may be more pronounced and may even show to the outside world. But it's just as likely that while your clothes may be getting a little tight, you won't yet have a noticeably pregnant belly at this point.
Pregnancy to-do list: Week 13. Although not all experts agree, some doctors recommend that you don't sleep on your back during the second and third trimesters because it puts the weight of your uterus on a large vein called the inferior vena cava, which runs behind your organs, close to your spine.
Early on in pregnancy, you can sleep on your stomach. Eventually, that position can become uncomfortable. But it's OK to sleep on your stomach if it is comfortable. Lying on your back is not recommended because of pressure on the inferior vena cava.
If you are pregnant and working, you may want to reduce or avoid: Stooping, bending, or squatting often. Lifting heavy objects from the floor or any location that requires you to bend or reach. Lifting overhead or reaching.
Depending on your stage of pregnancy, your body type, and even the time of day, sometimes your belly will feel soft and other times it will feel tight and hard. The reality is, there's no normal to compare yourself with. Pregnant bellies come in all shapes, sizes, and firmness.