Successful implantation usually does not cause any abnormal sensation, but some women may experience mild discomfort, similar to the feeling of menstrual flow. When the fertilized egg is implanted, the trophoblast cells will gradually secrete human chorionic gonadotropin, and a few women will experience abdominal pain due to the fluctuation of the hormone, accompanied by a small amount of vaginal bleeding, which is similar to that of the onset of menstruation, and lasts for about a week or so. However, most women will not experience similar symptoms at the time of implantation, and will only gradually experience early pregnancy reactions under the effect of hormones, such as nausea, vomiting, gastrointestinal discomfort, breast tenderness, and so on. Therefore, when symptoms of abdominal pain occur, you should first consider whether it is caused by menstruation or gastrointestinal discomfort, and should not rely solely on abdominal pain to determine whether or not implantation has occurred. If you find that your period is delayed and accompanied by abdominal pain, you can confirm whether you are pregnant by using an early pregnancy test or checking your blood HCG.