The first and most pressing reason behind sleep problems during pregnancy is the increasing size of the fetus, which can make it hard to find a comfortable sleeping position. If you've always been a back or stomach sleeper, you might have trouble getting used to sleeping on your side (as doctors recommend). Also, shifting around in bed becomes more difficult as the pregnancy progresses and your size increases.

Other common physical symptoms may interfere with sleep as well:

• The frequent urge to urinate: Your kidneys are working harder to filter the increased volume of blood (30% to 50% more than you had before pregnancy) moving through your body, and this filtering process results in more urine. Also, as your baby grows and the uterus gets bigger, the pressure on your bladder increases. This means more trips to the bathroom, day and night. The number of nighttime trips may be greater if your baby is particularly active at night.
• Increased heart rate: Your heart rate increases during pregnancy to pump more blood, and as more of your blood supply goes to the uterus, your heart will be working harder to send sufficient blood to the rest of your body.
• Shortness of breath: At first, your breathing may be affected by the increase in pregnancy hormones, which will cause you to breathe in more deeply. This might make you feel as if you're working harder to get air. Later on, breathing may feel more difficult as your enlarging uterus takes up more space, resulting in pressure against your diaphragm (the muscle just below your lungs).

• Leg cramps and backaches: Pains in your legs or back are caused in part by the extra weight you're carrying. During pregnancy, the body also produces a hormone called relaxin, which helps prepare the body for childbirth. One of the effects of relaxin is the loosening of ligaments throughout the body, making pregnant women less stable and more prone to injury, especially in their backs.
• Heartburn and constipation: Many women experience heartburn, which occurs when the stomach contents reflux back up into the esophagus. During pregnancy, the entire digestive system slows down and food tends to remain in the stomach and intestines longer, which may cause heartburn or constipation. Heartburn and constipation can both get worse later on in the pregnancy when the growing uterus presses on the stomach or the large intestine.

Your sleep problems may have other causes as well. Many pregnant women report that their dreams become more vivid than usual, and some even experience nightmares. Stress can interfere with sleep, too. Maybe you're worried about your baby's health, anxious about your abilities as a parent, or feeling nervous about the delivery itself. All of these feelings are normal, but they might keep you (and your partner) up at night.

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2. What positions should you avoid?
3. What to Do When You Can't Sleep?