Human Factors Affecting Recovery of Sperm Motility After Cryopreservation: A Retrospective Analysis
Michelle K. Li, Austin Fan, Mojgan Sabet, Darshan P. Patel, Tung-Chin HsiehBackground
Although studies have suggested that sperm motility may influence assisted reproductive technology outcomes, current studies on factors affecting post-cryopreservation motility recovery are largely limited to evaluating cryopreservation techniques.
Objective
To evaluate human factors associated with the recovery of sperm motility after cryopreservation.
Design
We retrospectively reviewed patients undergoing sperm cryopreservation at a single institution between September 2021 and January 2024.
Methods
Pre- and post-thaw motility, demographics, clinical history, and pre-retrieval laboratory values were collected. The primary outcome was percent motility recovery, defined as post-thaw motility divided by pre-freeze motility multiplied by 100. Multivariable linear regression was adjusted for baseline motility, age, BMI category, smoking status, alcohol use, race, chemotherapy exposure, and radiation exposure. A secondary model used absolute post-thaw motility to assess ratio-based ceiling effects.
Results
Among 184 patients, mean age was 30.4 (SD 9.07) and mean BMI was 25.9 (SD 4.87). Mean pre- and post-freezing sperm motility and percent recovery were 45.5% (SD 22.1), 23.7% (SD 13.8), and 53.9% (SD 24.5), respectively. Increasing age was associated with lower motility recovery (β=−0.525, p=0.015) and post-thaw motility (β=−0.178, p=0.025). Higher pre-freeze motility was inversely associated with percent recovery (β=−0.201, p=0.016), but positively associated with post-thaw (β=0.478, p<2*10 -16 ).
Conclusions
Advancing age was associated with lower proportional motility recovery and lower absolute post-thaw motility. The inverse association between baseline motility and percentage recovery likely reflects ratio-based mathematical constraints, not worse absolute post-thaw motility. Older patients may benefit from earlier or multiple cryopreservations to maximize motile sperm availability.