Tubal pregnancy (TP) accounts for approximately 98% of all types of ectopic pregnancies (EP). The incidence of tubal pregnancy has been increasing over the last decades. Clinically, early diagnosis of tubal pregnancy is somewhat difficult, with approximately 9% of patients with tubal pregnancy being asymptomatic and approximately half requiring emergency care due to emergency complications, imposing a substantial financial and emotional burden on the patient and society. Emergency contraceptive pills (ECPs) are a safe method that can prevent unintended pregnancies. Because it is over-the-counter, readily available and effective, more and more women are using levonorgestrel (LNG) for emergency contraception. Cases of tubal pregnancy after failed contraceptive use of levonorgestrel have been reported. Previous studies have shown that LNG is effective in reducing the risk of unintended pregnancies, including ectopic and intrauterine pregnancies; however, the risk of tubal pregnancy increases approximately fivefold when levonorgestrel is used in the event of contraceptive failure. Tubal pregnancy is often thought to be associated with tubal inflammation and its sequelae. However, clinical studies have found that many women with tubal pregnancy take levonorgestrel for this pregnancy and most do not have tubal damage or adnexal adhesions. It is not known whether the etiology differs between patients with tubal pregnancy in the general population and those with tubal pregnancy after failed LNG contraception. The aim of this study was to assess whether tubal inflammation and fibrosis were present in patients with tubal pregnancy after failed LNG contraception and whether the etiology was different compared to patients with tubal pregnancy in the usual setting. Professor Cheng Li, Department of Obstetrics and Gynecology, International Peace Maternal and Child Health Hospital and Department of Obstetrics and Gynecology, Shanghai Jiaotong University, conducted the study and published the results in the journal pharmacoepidemiology and drug safety. The study compared chronic tubal inflammation and fibrosis in tubal pregnancies in the normal setting and in tubal pregnancies after levonorgestrel contraceptive failure. The researchers found that chronic tubal inflammation was less common in patients with tubal pregnancy who failed levonorgestrel contraception. Although the pathogenesis of tubal pregnancy is not fully understood, it is currently believed that damage to the fertilized egg running in the fallopian tube or retention of the fertilized egg in the fallopian tube due to altered tubal microenvironment is the cause of pregnancy failure or early tubal implantation. In addition, pelvic inflammatory disease and tubo-ovarian adhesions may lead to abnormalities in the morphology and function of the fallopian tubes. Therefore, women with these conditions are more likely to have a tubal pregnancy. Among them, pelvic inflammatory disease is the most common factor leading to abnormal tubal morphology and function. In this study, four objective assays (including serum Chlamydia trachomatis testing, laparoscopy, histopathological analysis, and Masson staining) were used to assess whether tubal pregnancy after levonorgestrel contraceptive failure was associated with tubal inflammation, and it was found that tubal pregnancy after levonorgestrel contraceptive failure was unlikely to be caused by pelvic inflammatory disease and its associated sequelae. In this regard, it can only be speculated that ectopic pregnancy after levonorgestrel contraceptive failure may be related only to levonorgestrel administration and not caused by pelvic inflammatory disease or other factors. Levonorgestrel can terminate follicular development and therefore delay or inhibit ovulation. Previous studies have shown that high doses of levonorgestrel may reduce tubal cilia activity and that levonorgestrel also reduces tubal muscle contraction. Reduced ciliary motility and decreased muscle contraction lead to retained fertilized eggs, which may be the most important reason for the occurrence of tubal pregnancy. Therefore, the etiology of tubal pregnancy after levonorgestrel contraceptive failure is not the same as that of tubal pregnancy in general. Therefore, women using levonorgestrel for contraception need to be alert to the occurrence of tubal pregnancy, keeping in mind that pelvic inflammatory disease is not the only thing that can cause tubal pregnancy. Clinicians should also be careful to ask patients about their drug history and whether they have previously failed to take LNG contraception to prevent a tubal pregnancy from becoming a major problem.