Related Experiment Video
Updated: Sep 21, 2025
Author Spotlight: Advancing Therapeutic Strategies for Improving Pregnancy Rates by Analyzing Embryo-Endometrium Interactions
Published on: June 21, 2024
High dose gonadotropin stimulation increases endometrial thickness but this gonadotropin induced thickening does not
Isotta Martha Magaton1, Anja Helmer1, Marie Roumet2
1Division of Gynecological Endocrinology and Reproductive Medicine, University Women's Hospital, Inselspital, Friedbühlstrasse 19, Bern 3010, Switzerland.
Introduction:
Endometrial thickness <8 mm is related with lower pregnancy rates. This raises the question if endometrial thickness can be increased by gonadotropin stimulation to increase estradiol (E2) concentration and if such an artificial thickening of the endometrium has an effect on implantation. A model to address this question is the comparison of endometrial thickness and outcome parameters in conventional gonadotropin stimulated IVF (cIVF) compared to unstimulated natural cycle IVF (NC-IVF).
Material And Methods:
Retrospective study including 235 cIVF and 616 NC-IVF cycles without embryo selection and with fresh transfer on day 2 and 3 from 2015 to 2019. Endometrial and E2 measurements were included and analysed between day -4 and -2 (0 = day of aspiration). The effects of E2 on endometrial thickness, endometrial growth and the effect of endometrial thickness on implantation rates and live births were analysed.
Results:
Endometrial thickness was found to be higher in cIVF compared to NC-IVF (p < 0.001). On day -2, the day when ovulation was triggered, mean endometrial thickness was 9.75 ± 2.05 mm and 8.12 ± 1.66 mm, respectively. The increase in endometrial thickness slowed down with increasing E2 concentrations (time x estradiol concentration: -0.19, p = 0.010). Implantation rates were not significantly different in cIVF and NC-IVF cycles (clinical pregnancy rate: 19.1% vs. 15.4% p = 0.2; live birth rate: 12.8% vs. 11.7%, p = 0.8).
Conclusions:
Endometrial growth dynamic is different and endometrium is thicker in cIVF compared to NC-IVF. Pregnancy and live birth rates are not different. Gonadotropin induced thickening of the endometrium does not appear to improve implantation.
Related Concept Videos
01:20Proliferative Phase
Notably, the stratum basale, the basal layer of the endometrium, including the basal parts of the uterine glands, remains unaffected by menstruation. Stem cells in this layer undergo mitosis, regenerating the stratum functionalis and thickening the...
01:22Hormonal Regulation of the Menstrual Cycle
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH...
01:27Ovarian Cycle
02:07Oogenesis
01:24In Vitro Fertilization
The IVF process begins with ovarian stimulation, during which reproductive endocrinologists prescribe hormonal medications to stimulate the ovaries to produce multiple eggs instead of the single...
01:24Gonadal and Placental Hormones
In males, testosterone is the primary gonadal androgen. It plays a central role in the maturation of male reproductive organs — the penis and testes. Additionally, testosterone is instrumental in the development of secondary sexual characteristics — a deep voice as well as facial and pubic hair...