Level 1: What are the causes of insomnia in pregnant women? Pregnant women are prone to insomnia due to many changes in their bodies. Common causes include: physical discomfort, mood swings, hormonal changes, fetal movement, etc. Physical discomfort: During pregnancy, pregnant women may experience discomfort such as back pain, leg cramps, etc. due to the compression and expansion of the fetus, thus affecting the quality of their sleep. Mood swings: mood swings during pregnancy