Risk of ectopic pregnancy is linked to endometrial thickness in a retrospective cohort study of 8120 assisted reproduction technology cycles

Abstract

study question: Is endometrial combined thickness (ECT)measured prior to embryo transfer (ET) associated with ectopic pregnancy (EP)? summaryanswer: Following IVF, the risk of EP is 4-fold increased in womenwith an ECTof,9 mmcomparedwithwomenwith an ECT of .12 mm. what is known already: Known risk factors for EP include tubal damage,maternal cigarette smoking and endometriosis. EP is alsomore common following IVF but the underlying causes for this remain unclear. study design, size, duration: Retrospective cohort study restricted to all IVF cycles leaDing to a pregnancy (bhCG . 50 IU/l) between January 2006 andDecember 2014.Atotal of 6465 patients achieved a pregnancy in 8120 cycles.Cycles using preimplantation genetic screening or donor oocytes were excluded. participants/materials, setting, methods: This cohort consists of 6465 patients achieving a pregnancy in 6920 stimulated cycles with fresh embryo transfers (STIM ET) and 1200 hormone replacement therapy frozen embryo transfers (HRT-FET) cycles at a private IVF unit (Monash IVF, Melbourne, Australia). ECT was the primary independent variable of interest; the primary outcome was a diagnosis of EP. The dataset was analysed using binary logistic general estimating equations (SPSS v22.0) to calculate odds ratio (OR) for EP adjusted for known confounders (aOR). There was no loss to follow-up in the dataset. mainresults and the role of chance: The study groups did not differ significantly prior to IVF treatment. After adjusting for confounders, ECT remained statistically significant as an independent risk factor for EP.Comparedwithwomenwith an ECT of ,9 mm, womenwith an ECT of 9-12 mm had an aOR of 0.44 (95% CI 0.29-0.69, P, 0.01) and women with an ECT . 12 mm had an aOR of 0.27 (95% CI 0.10-0.77, P 0.01).These differences remained statistically significant after performing a sensitivity analysis excludingHRT-FET,smokers and patients with tubal infertility. limitations, reasons for caution: The study design is retrospective, and it is possible that not all confounders havebeen accounted for. Measurement of ECT was performed by highly trained sonographers, but some inconsistency between individuals may be present.