Level 1: Reasons why pregnant women sweat while sleeping at night. It is very common for pregnant women to sweat while sleeping at night. This is caused by changes in hormonal levels in the body during pregnancy. Hormone levels in pregnant women are constantly changing, and these changes can cause an imbalance in the body\’s temperature regulation, which can lead to nighttime sweating. Level 2: Pregnant women’s sweating at night is related to their physical condition.