1. Precautions for having sex during pregnancy. During pregnancy, having sex is very common. However, you need to pay attention to the following points when having sex: 1. Avoid having sex in the first trimester: In the first three months of pregnancy, the embryo is still very fragile. Therefore, it is best to avoid having sex during this period. 2. Avoid strenuous exercise: During pregnancy, a lot of things happen to a woman’s body.