1. What are the reactions during one month of pregnancy? In the first month of pregnancy, many women have no obvious physical reaction. This is because the embryo has just implanted and has not yet secreted enough progesterone to affect the mother\’s body. However, some subtle changes may still be noticeable, such as mild breast swelling, fatigue and occasional mild nausea. 2. Breast swelling and increased sensitivity After pregnancy, the breasts will gradually become more sensitive and swollen due to changes in hormonal levels. Some women may feel more small granular material appearing around their nipples.