EP25.16: Uterine contractility not associated with changes in pregnancy outcome in oocyte donor recipients with normal uteri

Are differences in uterine contractility associated with different IVF/ICSI pregnancy outcomes in donor oocyte recipients with normal uteri? This ongoing multi-centre prospective observational cohort study investigates uterine contractility on transvaginal ultrasound (TVUS). Our study included patients undergoing IVF/ICSI treatment using oocyte donation with good quality TVUS recordings and sonographically and hysteroscopically normal uteri from 2021 to 2023. 21 IVF/ICSI patients undergoing embryo transfer (ET) after oocyte donation were included from Embryolab Fertility Clinic in Thessaloniki Greece. Patients were included up to the age of 50 years, and were undergoing IVF/ICSI due to age or ovarian insufficiency. Patients underwent hormone replacement therapy in preparation, with ET performed at an endometrial thickness of >7mm. Single embryo transfer of good quality embryos in the blastocyst stage was performed. All patients underwent an TVUS measurement of uterine contractility within 1 hour prior to ET. Uterine contraction frequency, amplitude, velocity and coordination were measured by applying dedicated speckle tracking and strain analysis. A multivariate analysis was conducted to correct for potential confounders of age, BMI, duration of infertility, gravidity, parity. 13/21 (61.9%) patients achieved ongoing pregnancies. Patient ages, BMI, gravidity, parity, endometrial thickness, number of previous IVF cycles and infertility durations were comparable between pregnant and non-pregnant groups (P > 0.05). No significant differences in contraction frequency (p= 0.170), amplitude (p = 0.387), velocity (p = 0.099) or coordination (p = 0.483) are reported between pregnant versus non-pregnant patients. These results suggest that in oocyte donor recipients with normal uteri, uterine contractility does not significantly differ between pregnant versus non-pregnant groups, potentially due to the lack of a uterine factor in these women. How this may differ in women with abnormal uteri merits investigation.