Occasional pain in the lower abdomen on the 40th day of pregnancy is most commonly due to the ligamentous pulling pain that occurs with the enlargement of the uterus after pregnancy, which is mild and does not cause bleeding. In addition, it is recommended to exclude the pain in the lower abdomen caused by preeclampsia, through ultrasound examination, to understand whether the size of the intrauterine gestational sac and the number of days of menopause are in line with the phenomenon of accumulation of blood in the uterine cavity, and through the blood sampling and examination of blood HCG and progesterone, a comprehensive analysis of the decision on whether it is necessary to give treatment to stabilize the fetus. If you are 40 days pregnant and have not had an ultrasound, and you are not sure of intrauterine pregnancy, it is recommended that you have an ultrasound as soon as possible to rule out the possibility of ectopic pregnancy.