An introduction to early pregnancy reactions Pregnancy is a major event in a woman’s life, and early pregnancy is the period when pregnant mothers experience the most discomfort during pregnancy. Reactions during pregnancy include nausea, vomiting, fatigue, headache, diarrhea, constipation, drowsiness, mood swings, etc. These reactions are more common in the first trimester. This article will elaborate on the early pregnancy reactions from several aspects and introduce