5 Citations (Scopus)


RESEARCH QUESTION: What is the association between the development of pre-eclampsia and endometrial preparation prior to vitrified-warmed embryo transfer (frozen embryo transfer, FET)?

DESIGN: A retrospective cohort study at a tertiary university-based hospital, including a total of 536 pregnant patients who underwent a FET between 2010 and 2019 and delivered in the same institution; 325 patients underwent natural cycle FET (NC-FET) and 211 artificial cycle FET (AC-FET).

RESULTS: Unadjusted, the incidence of pre-eclampsia was significantly higher in AC-FET cycles than in NC-FET cycles (3.7% versus 11.8%, P < 0.001). Multivariable logistic regression analysis showed that, when adjusting for type of endometrial preparation (artificial cycle versus natural cycle), oocyte recipient cycles and African ethnicity, the risk of developing pre-eclampsia was significantly associated with artificial endometrial preparation or oocyte recipient cycles (AC-FET versus NC-FET: odds ratio 2.9, 95% confidence interval 1.4-6.0, P = 0.005).

CONCLUSIONS: The current data show a higher incidence of pre-eclampsia in AC-FET versus NC-FET cycles, adding further strength to the existing data on this topic. Together, these recent findings may result in a change in clinical practice, towards a preference for NC-FET cycles over AC-FET cycles in ovulatory patients. Screening for high-risk patients and the development of strategies to mitigate their risk profile could reduce the risk of pre-eclampsia. Further understanding of the different vasoactive substances excreted by the corpus luteum is vital.

Original languageEnglish
Pages (from-to)915-922
Number of pages8
JournalReproductive Biomedicine Online
Issue number5
Early online date25 Dec 2021
Publication statusPublished - May 2022

Bibliographical note

Copyright © 2021. Published by Elsevier Ltd.


  • Hormone replacement therapy
  • Hypertensive disorders of pregnancy
  • Natural cycle
  • Pre-eclampsia
  • Vitrified–warmed embryo transfer


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