P-493 Bleeding during early pregnancy after Hormone Replacement Therapy Frozen Embryo Transfer (HRT-FET) – is it more common than we think?

Abstract

Abstract Study question How common is bleeding in early pregnancy after HRT-FET? And does bleeding affect the reproductive outcome in this population? Summary answer A total of 47% of HRT-FET patients experience bleeding before the 8th week of gestation, however, bleeding does not seem to affect the reproductive outcome. What is known already Bleeding occurs in 20% of spontaneously conceived pregnancies. Most pregnancies will proceed to term although episodes of heavy bleeding are associated with an increased risk of miscarriage. The prevalence of bleeding after assisted reproductive technology including in vitro fertilization seems to be higher and, in some reports, up to 36%. However, the knowledge is scanty and in particular the knowledge regarding bleeding during HRT-FET is sparse. As HRT-FET in clinical practice increases, knowledge on the occurrence of early bleeding during pregnancy and the impact on the reproductive outcome in this population is needed. Study design, size, duration We performed a cohort study including 489 patients undergoing HRT-FET. The trial was conducted from January 2020 to November 2022 in a public fertility clinic. Participants/materials, setting, methods Patients with autologous vitrified blastocyst were treated in a standard HRT-FET protocol. In the event of a positive HCG-test an early pregnancy scan was performed around 8 weeks of gestation. During this visit the women answered a questionnaire covering pregnancy related symptoms, wellbeing, and if bleeding occurred, the type and duration of the bleeding. The information was verified through medical files. Main results and the role of chance In this HRT-FET cohort we found that a total of 47% (150/322) of patients with a positive pregnancy test experienced bleeding before 8 weeks of gestation. Mostly the bleeding was described as spotting with a median of 2 days (range 0.5—16 days). Out of 150 patients with one or several bleeding episodes, a total of 107 patients (71 %) had an ongoing pregnancy at 12 weeks of gestation. In comparison, 172 patients reported no bleeding episodes and a total of 115 (67%) of these patients had an ongoing pregnancy at 12 weeks of gestation. This difference was found to be non-significant (p = 0,39). Limitations, reasons for caution The patients in our study were treated in a standard HRT-FET protocol. The results may not be transferable to other treatment protocols. Also the data is based on patients self-reported symptoms. Therefore some degree of recall bias may be present. Wider implications of the findings Episodes of early bleeding during pregnancy are associated with distress for the pregnant woman – especially in previously infertile patients. Knowledge about the frequent occurrence of bleeding during early pregnancy after HRT-FET and that this does not affect the reproductive outcome will help the clinician reassure and guide the patient. Trial registration number 2019-001539-29