In vitro fertilization outcomes in a mouse model of gender-affirming hormone therapy in transmasculine youth

Abstract

Objective: To investigate in vitro fertilization (IVF) outcomes in an adolescent transmasculine mouse model mimicking gender-affirming hormone therapy in prepubertal youth, both on testosterone (T) and after T washout.

Design: Experimental laboratory study using a validated mouse model.

Setting: University-based basic science research laboratory.

Animal(s): A total of 80 prepubertal 26-day-old C57BL/6N female mice were used in this study.

Intervention(s): Animals (n = 10/group) were implanted subcutaneously with gonadotropin-releasing hormone agonist at 3.6 mg or received sham surgery. After 21 days, they were implanted with silastic tubing containing either T 10 mg or placebo for 6 weeks. After 6 weeks, a group of animals were superovulated for immediate IVF, and another group had the implant removed and went through superovulation for IVF after 2 weeks (washout IVF). The total number of oocytes yielded, oocyte maturity rate, fertilization rate, and numbers of 2-cell embryos, 4-8-cell embryos, morula, blastocysts, and hatching blastocysts were recorded.

Result(s): Testosterone treatment negatively impacted IVF outcomes in animals stimulated when receiving T, but not after T washout. Pretreatment with gonadotropin-releasing hormone agonist did not affect IVF outcomes.

Conclusion(s): Although current T had a negative impact on IVF outcomes compared with controls, animals were still able to produce viable oocytes for fertilization and develop into blastocysts. Future efforts to study the impact of long-term T exposure on oocyte quality, especially aneuploidy rates, pregnancy outcomes, and live birth rates, are necessary.

Keywords: GnRH agonist; Mouse model; fertility outcomes; testosterone; transmasculine youth.