Level 1: Causes of headaches in pregnant women There are many causes of headaches in pregnant women, the most common of which is changes in hormonal levels. During pregnancy, hormonal levels in women undergo dramatic changes, which can cause blood vessels to dilate and contract erratically, causing headaches. In addition, pregnancy may also be accompanied by physical conditions such as anemia, dehydration, and hypotension, which can also be triggers for headaches. Level 2: How to prevent headaches in pregnant women. Methods to prevent headaches in pregnant women mainly include the following points: 1. Maintain adequate sleep: