Most women experience nausea and vomiting around day 42 of pregnancy. After sex, the egg and sperm will unite and develop into a fertilized egg. With the increase of HCG around 40 days after menopause, women will experience nausea, vomiting and other early pregnancy reactions, which is not a necessary reaction for every woman after pregnancy. Some women are more sensitive to hormonal elevation or physical factors and may experience nausea at the 30th day of menopause, or they may not experience nausea or vomiting at all times, but they may also experience general fatigue and weakness, breast tenderness and other discomfort, which is also normal.