First trimester (weeks 0 to 14)

Many physiological changes that occur in the first trimester can influence your sleep.

• Your body goes through hormonal changes at the onset of pregnancy. High progesterone levels make you tired during the day, but can also keep you up at night, while an increase in estrogen may destabilize your sleep cycle.
• Hypersensitive breasts and other pregnancy aches and pains can make it difficult to find a comfortable sleeping position. To alleviate discomfort, try to sleep on your side.
• During pregnancy, your baby puts increasing pressure on your bladder, which will make you have to urinate more often. The urge to urinate may even wake you up several times a night.
• If you experience severe morning sickness, it may cause you to get up earlier in the morning. Vomiting can also decrease your nutritional intake. If you’ve cut back on your usual morning coffee, the lack of caffeine may increase your fatigue.
• Anxiety and stress related to your pregnancy can lead to insomnia.

Second trimester (weeks 15 to 28)

In general, sleep disturbances are less common in the second trimester. As hormone levels stabilize, feelings of fatigue and nausea decrease.

What’s more, as your uterus and baby rise up into your abdomen, they take pressure off your bladder and decrease the need for frequent urination.

However, some physical discomforts may still disturb your sleep.

• Your growing uterus begins to press on your stomach and intestines. This can cause heartburn.
• Your REM periods are more frequent, so you may have more dreams and nightmares. Some of these may seem extremely vivid, as the more often you wake up, the easier it is to remember your dreams.

Third trimester (week 29 to birth)

Your sleep may be affected for numerous reasons during the last trimester of pregnancy.

• Your growing baby and increasingly heavy stomach may cause back pain, muscle aches, and a general sense of discomfort.
• Heartburn and acid reflux may also disturb your sleep.
• In preparation for childbirth, your body releases hormones that relax your ligaments and joints. These changes may make it difficult to find a comfortable sleeping position.
• Nasal congestion and pressure from the uterus on the diaphragm sometimes cause pregnant women to snore. Some women even suffer from sleep apnea during pregnancy. However, in some cases, sleep apnea and snoring signal other pregnancy issues. If you experience sleep problems during pregnancy, speak to your doctor or midwife.
• Pregnant women may also have leg cramps. These may be caused by increased blood flow in the legs affecting your muscles and nerves. Cramps may also be due to higher iron, folic acid (vitamin B9), or calcium levels.

Sleeping for longer stretches (8 to 10 hours), taking naps, eating a balanced diet, staying hydrated, and exercising regularly can improve your sleep quality. If in doubt, speak with your health care provider.

The best sleeping positions

The best sleeping position during pregnancy is on your side.

• Lie on the side that feels most comfortable. Some experts recommend the left side because this decreases blood pressure and improves blood flow to your vital organs and the baby.
• Bend your knees and place a pillow between them.
• Consider using a pregnancy pillow.
• When lying on your side, place a pillow beneath your abdomen to support the weight of your stomach.
• If heartburn is disrupting your sleep, try elevating your upper body.
• You can also change your position during the night.

However, as of the 24th week, you should avoid sleeping on your back. In this position, your uterus presses on certain blood vessels, which can decrease the amount of nutrients and oxygen carried to your baby. Sleeping on your back can also cause back pain and digestive discomfort. However, don’t worry if you wake up like this. Simply change positions.

As pregnancy progresses, some women have trouble sleeping on their stomach. However, there is no harm in sleeping in this position if you’re comfortable.

Things to keep in mind

• Physiological changes during pregnancy can impact your sleep patterns.
• The best sleeping position during pregnancy is on your side.
• Avoid sleeping on your back as of the 24th week.

Scientific review: Dr. Jean-Philippe Blais, family physician at a perinatal clinic Research and copywriting: The Naître et grandir team Updated: October 2019