RESEARCH QUESTION What is the frequency of cervical pregnancy in women undergoing assisted reproductive technologies (ART) and what are the risk factors? DESIGN Case-control study of women undergoing assisted reproductive technology (ART) at 25 private assisted reproduction clinics run by the same group in Spain. Two control groups (tubal ectopic pregnancies and intrauterine pregnancies) were established. The main outcome measure was frequency of cervical pregnancy. Demographic, clinical factors and IVF parameters were assessed for their influence on cervical pregnancy risk. RESULTS Thirty-two clinical pregnancies were achieved out of 91,067 ongoing pregnancies, yielding a rate of 3.5/10,000. Cervical pregnancies represented 2.02% of all ectopic pregnancies (32/1582). The main risk factors two or more previous pregnancies (OR 2.68; CI 1.18 to 6.07); two or more previous miscarriages (OR 4.21; CI1.7 to 10.43), one or more previous curettages (OR 3.99, CI 1.67 to 9.56), two or more previous curettages (OR 4.71; CI 1.19 to 18.66) and smoking (OR 2.82 CI 1.14 to 6.94). History of caesarean sections and tubal pregnancy was not associated with an elevated cervical pregnancy risk. Infertility conditions and endometrial thickness were similar across the three groups. The proportion of women from whom fewer than 10 oocytes were retrieved was higher in the clinical pregnancy group than in the IUP group. CONCLUSIONS In ART, the main risk factors for cervical ectopic pregnancy are a history of at least two pregnancies, miscarriages, at least one curettage and smoking. IVF parameters do not seem to influence the development of clinical pregnancies. Cervical pregnancies are less common in ART than previously reported, attributable to improvements in ART; a publication bias in early IVF reports cannot be ruled out.

中文翻译：

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宫颈妊娠辅助生殖：分析91,067例正在进行的妊娠的危险因素。

研究问题接受辅助生殖技术（ART）的妇女宫颈妊娠的频率是多少？危险因素是什么？设计在西班牙同一小组经营的25家私人辅助生殖诊所中，对接受辅助生殖技术（ART）的妇女进行病例对照研究。建立了两个对照组（输卵管异位妊娠和宫内妊娠）。主要结果指标是宫颈妊娠的频率。评估了人口统计学，临床因素和IVF参数对子宫颈妊娠风险的影响。结果在91,067例正在进行的妊娠中，有32例临床妊娠，发生率为3.5 / 10,000。宫颈妊娠占所有异位妊娠的2.02％（32/1582）。主要危险因素是两次或两次以上怀孕（OR 2.68; CI 1.18至6。07）; 两次或多次先前流产（OR 4.21; CI1.7至10.43），一次或多次先前刮宫（OR 3.99，CI 1.67至9.56），两次或更多次先前刮宫（OR 4.71; CI 1.19至18.66）和吸烟（OR 2.82 CI 1.14至6.94）。剖宫产和输卵管妊娠史与宫颈妊娠风险升高无关。三组的不孕情况和子宫内膜厚度相似。临床妊娠组中获得不到10个卵母细胞的女性比例高于IUP组。结论在ART中，宫颈异位妊娠的主要危险因素是至少两次怀孕，流产，至少一次刮宫和吸烟史。试管婴儿参数似乎并不影响临床妊娠的发展。由于抗逆转录病毒治疗的改善，宫颈妊娠在抗逆转录病毒治疗中不如以前报道的那么普遍。不能排除早期IVF报告中的出版偏见。