Women with a diagnosed EP (based on the American College of Obstetricians and Gynecologists [ACOG] Practice Bulletin[18]) who were seen in the inpatient department of gynecology of each hospital were interviewed as potential EP subjects. LDN193189 = 0.04 [0.030.05]; withdrawal method: AOR = 0.10 [0.070.13]; calendar rhythm method: AOR = 0.54 [0.400.73]; oral contraceptive pills [OCPs]: AOR = 0.03 [0.020.08]; levonorgestrel emergency contraception [LNG-EC]: AOR = 0.22 [0.160.30]; IUDs: AOR = 0.01 [0.0050.012]; tubal sterilization: AOR = 0.01 [0.0010.022]) and unwanted EP (condom: CSF3R AOR1= 0.05 [0.040.06]; withdrawal method: AOR1= LDN193189 0.13 [0.090.19]; calendar rhythm method: AOR1= 0.66 [0.480.91]; OCPs: AOR1= 0.14 [0.070.26]; IUDs: AOR1= 0.17 [0.130.22]; tubal sterilization: AOR1= 0.04 [0.020.08]). However, when contraception failed and pregnancy occurred, current use of OCPs (AOR2= 4.06 [1.6410.07]), LNG-EC (AOR2= 4.87 [3.886.10]), IUDs (AOR2= 21.08 [13.4433.07]), and tubal sterilization (AOR2= 7.68 [1.6934.80]) increased the risk of EP compared with the non-use of contraceptives. == Conclusion == Current use of most contraceptives reduce the risk of both IUP and EP. However, if the contraceptive method fails, the proportions of EP may be higher than those of non-users. In the case of contraceptive failure in the current cycle, EP cases should be differentiated according to current use of OCPs, LNG-EC, IUDs, and tubal sterilization. In addition, attention should be paid to women with previous long-term use of IUDs. == Introduction == Ectopic pregnancy (EP) is a major cause of maternal morbidity and, occasionally, mortality. Better understanding of the risk factors for EP can aid in early diagnosis and avoid potentially life-threatening emergencies and the resulting physical and psychological harm to women[1]. In recent decades, the incidence of EP has increased[2]. Contraceptive failure has been considered one LDN193189 of the important factors associated with this increased EP incidence[3]. The use of long-term contraceptives, including intrauterine devices (IUDs), oral contraceptive pills (OCPs), and tubal sterilization, and short-term contraceptive methods, such as condoms, rhythm methods, withdrawal, and levonorgestrel emergency contraception (LNG-EC), are the most commonly used methods in China[4]. All of these contraceptives, whether hormonal or mechanical, can effectively protect women from unintended pregnancy. However, any form of contraceptive has a certain probability of failure, which can lead to an unexpected pregnancy, including an EP. One study revealed that contraceptive devices may be less effective for ectopic pregnancy prevention than for intrauterine pregnancy prevention, meaning that pregnancies resulting from contraceptive failure may be more likely to be ectopic[2]. The risk of EP resulting from contraceptive failure varies according to the contraceptive method used[5]. In 1995, Parazziniet al.conducted a case-control study on the relationship between the past use of contraceptives and the risk of EP[6]. However, with the more recent improvements in various contraceptive methods, including IUDs and OCPs, it remains unknown whether the association between these methods and the risk of EP is consistent with that reported decades ago. Furthermore, although novel methods, such as LNG-EC, have been widely used because of their high efficiency and good tolerance, cases of EP following LNG-EC failure have been consistently reported[7][12]. It remains unclear whether LNG-EC failure increases the risk LDN193189 of EP. Since the 1990s, attitudes toward different methods have changed[13][15], as has the overall prevalence of contraceptive use in China[4],[16]. Therefore, we were interested in the association between the risk of EP and the use of common contraceptives after the patterns of contraceptive use LDN193189 changed. Additionally, neither the study by Parazziniet al.nor other epidemiology studies has reported the association between EP risk and current use of various contraceptives since 1995. For the abovementioned reasons, we designed this case-control study and conducted it in five medical hospitals in Shanghai to re-evaluate the relationship between EP risk and common contraceptive methods used during the previous and current menstrual cycle. According to Weisset al., the odds ratio (OR) of the relationship between contraceptives and EP risk in case-control studies can vary depending on the composition of the control group[17]. Thus, a group of women with intrauterine pregnancy (IUP) and a group of nonpregnant women were recruited to constitute the control group. == Materials and Methods == == Study design and participants == This case-control study was conducted from March 2011 through April 2013 at five medical hospitals in Shanghai (two general hospitals and three maternity hospitals). The objective of this study was to evaluate the association between EP risk and the use of different contraceptives in the previous conception cycle and the association between EP and contraceptive.