Eva R Groenewoud1, Ben J Cohlen2, Amani Al-Oraiby3, Egbert A Brinkhuis4, Frank J M Broekmans5, Jan-Peter de Bruin6, Grada van Dool7, Katrin Fleisher8, Jaap Friederich1, Mariëtte Goddijn9, Annemieke Hoek10, Diederik A Hoozemans11, Eugenie M Kaaijk12, Caroliene A M Koks13, Joop S E Laven14, Paul J Q van der Linden15, A Petra Manger16, Minouche van Rumste17, Taeke Spinder18, Nick S Macklon5,19,20. 1. Department of Obstetrics and Gynecology, Noordwest Ziekenhuis, Den Helder, the Netherlands. 2. Isala Fertility Center, Isala, Zwolle, the Netherlands. 3. Department of Obstetrics and Gynecology, Amphia Hospital, Breda, the Netherlands. 4. Department of Obstetrics and Gynecology, Meander Medical Center, Amersfoort, the Netherlands. 5. Department for Reproductive Medicine, University Medical Center, Utrecht, the Netherlands. 6. Department of Obstetrics and Gynecology, Jeroen Bosch Hospital's, Hertogenbosch, the Netherlands. 7. Department of Obstetrics and Gynecology, Albert Schweitzer Hospital, Zwijndrecht, the Netherlands. 8. Department of Obstetrics and Gynecology, University Medical Center Nijmegen, Nijmegen, the Netherlands. 9. Center for Reproductive Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands. 10. Department of Obstetrics and Gynecology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands. 11. Department of Obstetrics and Gynecology, Medisch Spectrum Twente, Enschede, the Netherlands. 12. Department of Obstetrics and Gynecology, Onze Lieve Vrouwe Gasthuis, Amsterdam, the Netherlands. 13. Department of Obstetrics and Gynecology, Máxima Medical Center, Veldhoven, the Netherlands. 14. Department of Obstetrics and Gynecology, Erasmus Medical Center Rotterdam, Rotterdam, the Netherlands. 15. Department of Obstetrics and Gynecology, Deventer Hospital, Deventer, the Netherlands. 16. Department of Obstetrics and Gynecology, Diakonessenhuis, Utrecht, the Netherlands. 17. Department of Obstetrics and Gynecology, Catharina Hospital, Eindhoven, the Netherlands. 18. Department of Obstetrics and Gynecology, Medisch Centrum Leeuwarden, Leeuwarden, the Netherlands. 19. London Women's Clinic, London, UK. 20. Department of Obstetrics and Gynecology, University Hospital Zealand, Roskilde, Denmark.
Abstract
INTRODUCTION: Pregnancy after frozen-thawed embryo transfer (FET) is a multifactorial process. Although embryo quality is a key factor in determining pregnancy, other factors, including maternal determinants, are also considered to be predictive. Even though an association between endometrial thickness measured by transvaginal ultrasound and pregnancy rates has been reported in patients undergoing various assisted reproductive technology treatments, whether endometrial thickness predicts achieving pregnancy after natural cycle FET (NC-FET) remains unclear. MATERIAL AND METHODS: In this cohort study, 463 patients allocated to themodified NC-FET (mNC-FET) arm of a previously published randomized controlled trial were included. Monitoring in mNC-FET cycles consisted of regular ultrasound scans, measuring both dominant follicle and endometrial thickness. When the dominant follicle reached a size of 16-20 mm, an injection of human chorionic gonadotrophin was administered and embryo thawing and transfer planned. No minimal endometrial thickness was defined below which transfer was to be deferred. The primary endpoint was ongoing pregnancy rate. RESULTS: Overall, the ongoing pregnancy rate per started FET cycle was 12.5%. Multivariate regression analyses showed that embryo quality was the only significant predictor for ongoing pregnancy. Mean endometrial thickness did not differ between patients achieving ongoing pregnancy and those who did not (9.0 vs. 8.8 mm, p = 0.4). Comparable results were obtained with regard to clinical pregnancy, live birth and miscarriage rates. The area under the receiver operator curve was 0.5, indicating little discriminatory value of endometrial thickness. CONCLUSIONS: Given that endometrial thickness was not found to be predictive of pregnancy after mNC-FET, cancellation based on endometrial thickness alone may not be justified.
RCT Entities:
INTRODUCTION: Pregnancy after frozen-thawed embryo transfer (FET) is a multifactorial process. Although embryo quality is a key factor in determining pregnancy, other factors, including maternal determinants, are also considered to be predictive. Even though an association between endometrial thickness measured by transvaginal ultrasound and pregnancy rates has been reported in patients undergoing various assisted reproductive technology treatments, whether endometrial thickness predicts achieving pregnancy after natural cycle FET (NC-FET) remains unclear. MATERIAL AND METHODS: In this cohort study, 463 patients allocated to the modified NC-FET (mNC-FET) arm of a previously published randomized controlled trial were included. Monitoring in mNC-FET cycles consisted of regular ultrasound scans, measuring both dominant follicle and endometrial thickness. When the dominant follicle reached a size of 16-20 mm, an injection of human chorionic gonadotrophin was administered and embryo thawing and transfer planned. No minimal endometrial thickness was defined below which transfer was to be deferred. The primary endpoint was ongoing pregnancy rate. RESULTS: Overall, the ongoing pregnancy rate per started FET cycle was 12.5%. Multivariate regression analyses showed that embryo quality was the only significant predictor for ongoing pregnancy. Mean endometrial thickness did not differ between patients achieving ongoing pregnancy and those who did not (9.0 vs. 8.8 mm, p = 0.4). Comparable results were obtained with regard to clinical pregnancy, live birth and miscarriage rates. The area under the receiver operator curve was 0.5, indicating little discriminatory value of endometrial thickness. CONCLUSIONS: Given that endometrial thickness was not found to be predictive of pregnancy after mNC-FET, cancellation based on endometrial thickness alone may not be justified.