title: Risk factors for ectopic pregnancy in assisted reproductive technology: a 6-year, single-center study.
abstract: To explore factors affecting the incidence of ectopic pregnancy (EP) in assisted reproductive technology (ART).
  
  
  
  A retrospective cohort study on the incidence of EPs in IVF/intracytoplasmic sperm injection (ICSI) and IUI cycles from June 2009 to August 2015. Age of patients, tubal factor infertility, type of cycle (fresh or thawed), embryo being transferred (cleavage embryo or blastocyst), and number of embryos transferred were analyzed to explore their relationship with the incidence of EP.
  
  
  
  Teaching hospital.
  
  
  
  A total of 18,432 pregnancies resulting from ART treatment were retrospectively analyzed.
  
  
  
  None.
  
  
  
  Ectopic pregnancy rate.
  
  
  
  For IVF/ICSI cycles, the incidence of EP was different between cycles transferred with cleavage embryo and blastocyst (3.45% vs. 2.47%). In multivariate logistic regression analysis, tubal infertility was associated with EP (adjusted odds ratio 1.716, 95% confidence interval 1.444-2.039). For IUI cycles, EP was significantly higher in stimulated cycles compared with natural cycles (2.62% vs. 0.99%). The EP rate in cycles with sperm from donor and husband was 1.08% and 3.54%, respectively. However, when patients were stratified according to tubal infertility, the EP rate increased with level of peak estrogen. In thawed embryo transfer cycles, the EP rate was lower in blastocyst transfer cycles and in cycles transferred with fewer embryos.
  
  
  
  Irrespective of tubal infertility, for fresh IVF/ICSI cycles the rate of EP is positively associated with ovarian stimulation; for thawed IVF/ICSI cycles, blastocyst transfer or transfer with fewer embryos reduces the EP rate. In IUI cycles, EP is associated with sperm source.
authors.affiliation: Reproductive Medical Center, First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China.
authors.forename: Zhiqin
authors.initials: Z
authors.lastname: Bu
authors.affiliation: Reproductive Medical Center, First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China; Department of Obstetrics and Gynecology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, People's Republic of China.
authors.forename: Yujing
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: School of Public Health, Zhengzhou University, Zhengzhou, People's Republic of China.
authors.forename: Keyan
authors.initials: K
authors.lastname: Wang
authors.affiliation: Reproductive Medical Center, First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China. Electronic address: syp2008@vip.sina.com.
authors.forename: Yingpu
authors.initials: Y
authors.lastname: Sun
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D002681:China / Q000453:epidemiology; D015925:Cryopreservation; D004624:Embryo Transfer / Q000009:adverse effects; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects; D006784:Hospitals, Teaching; D006801:Humans; D015994:Incidence; D007247:Infertility, Female / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy*; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D010062:Ovulation Induction / Q000009:adverse effects; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000175:diagnosis / Q000453:epidemiology*; D027724:Reproductive Techniques, Assisted / Q000009:adverse effects*; D012189:Retrospective Studies; D012307:Risk Factors; D020554:Sperm Injections, Intracytoplasmic / Q000009:adverse effects; D013997:Time Factors; D016896:Treatment Outcome
keywords: ART; ectopic pregnancy; relative risk; tubal factor