News | Study: Testosterone Therapy May Affect IVF Success in Transgender Men, Mouse Model Offers New Clues
A mouse study presented at the Endocrine Society's 2022 annual meeting (ENDO 2022) suggests that ongoing testosterone therapy may adversely affect in vitro fertilization (IVF) outcomes in transgender men. The effect may be reversible if testosterone is paused before treatment.
The study was led by Dr. Amanda Schwartz, a reproductive endocrinology and infertility researcher at the University of Michigan. The team initially hypothesized that testosterone would not affect IVF outcomes, but the experimental data suggested otherwise.
Mouse model compared continued and discontinued treatment
The study used 38 female mice implanted with silicone tubing at 10 weeks of age to model hormone implants. Twenty received injections containing 10 milligrams of testosterone acetate, while 18 received ethanol as controls. The mice were divided into four groups:
Current testosterone treatment (Current T)
Continuous control (Sham implant)
Discontinued testosterone treatment (T Cessation)
Discontinued control (Control Cessation)
Researchers monitored testosterone levels and reproductive cycles. After 12 weeks, mice in the continued-treatment groups received ovarian stimulation, while those in the cessation groups received the same treatment two weeks after implant removal.
Key finding: Continued testosterone reduced egg numbers and embryo quality
Mice still receiving testosterone produced fewer retrieved eggs—only 17 compared with 36 in controls. They also had significantly fewer mature eggs (13 vs. 28.1) and two-cell embryos (12.78 vs. 26.9).
Although maturation and fertilization rates did not differ significantly, embryos retrieved from mice on continued testosterone produced a live birth rate of only 25%, well below the control group's 80%.
In contrast, mice that discontinued testosterone showed no significant differences from untreated mice in total egg number, mature egg number, or embryo quality.
Expert view: Pausing testosterone may reverse reproductive effects
“These results suggest that the negative effects of testosterone on ovarian function and IVF outcomes are reversible,” Dr. Amanda Schwartz said. “This provides a substantive basis for fertility guidance for transgender men who want to preserve fertility.”
Current Endocrine Society clinical practice guidelines recommend fertility preservation counseling before gender-affirming treatment begins.
Further research is needed
Although the study provides important clues, the researchers emphasized that the findings come from an animal model and cannot be directly applied to humans. “We need more research to fully understand the long-term effects of testosterone therapy on reproductive potential in transgender people,” Dr. Schwartz said.
News | Study: Testosterone Therapy May Affect IVF Success in Transgender Men, Mouse Model Offers New Clues
News | Study: Testosterone Therapy May Affect IVF Success in Transgender Men, Mouse Model Offers New Clues
A mouse study presented at the Endocrine Society's 2022 annual meeting (ENDO 2022) suggests that ongoing testosterone therapy may adversely affect in vitro fertilization (IVF) outcomes in transgender men. The effect may be reversible if testosterone is paused before treatment.
The study was led by Dr. Amanda Schwartz, a reproductive endocrinology and infertility researcher at the University of Michigan. The team initially hypothesized that testosterone would not affect IVF outcomes, but the experimental data suggested otherwise.
Mouse model compared continued and discontinued treatment
The study used 38 female mice implanted with silicone tubing at 10 weeks of age to model hormone implants. Twenty received injections containing 10 milligrams of testosterone acetate, while 18 received ethanol as controls. The mice were divided into four groups:
Current testosterone treatment (Current T)
Continuous control (Sham implant)
Discontinued testosterone treatment (T Cessation)
Discontinued control (Control Cessation)
Researchers monitored testosterone levels and reproductive cycles. After 12 weeks, mice in the continued-treatment groups received ovarian stimulation, while those in the cessation groups received the same treatment two weeks after implant removal.
Key finding: Continued testosterone reduced egg numbers and embryo quality
Mice still receiving testosterone produced fewer retrieved eggs—only 17 compared with 36 in controls. They also had significantly fewer mature eggs (13 vs. 28.1) and two-cell embryos (12.78 vs. 26.9).
Although maturation and fertilization rates did not differ significantly, embryos retrieved from mice on continued testosterone produced a live birth rate of only 25%, well below the control group's 80%.
In contrast, mice that discontinued testosterone showed no significant differences from untreated mice in total egg number, mature egg number, or embryo quality.
Expert view: Pausing testosterone may reverse reproductive effects
“These results suggest that the negative effects of testosterone on ovarian function and IVF outcomes are reversible,” Dr. Amanda Schwartz said. “This provides a substantive basis for fertility guidance for transgender men who want to preserve fertility.”
Current Endocrine Society clinical practice guidelines recommend fertility preservation counseling before gender-affirming treatment begins.
Further research is needed
Although the study provides important clues, the researchers emphasized that the findings come from an animal model and cannot be directly applied to humans. “We need more research to fully understand the long-term effects of testosterone therapy on reproductive potential in transgender people,” Dr. Schwartz said.
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