Geographic variation in semen parameters from data used for the World Health Organization semen analysis reference ranges

Abstract

Objective: To study geographic variations in sperm parameters using data from the trials that defined the reference ranges of the World Health Organization 2021 manual.

Design: Retrospective evaluation of the data used to define the World Health Organization reference ranges.

Setting: Not applicable.

Patient(s): Data from 11 studies, including 3,484 participants across 5 continents.

Intervention(s): The data were divided according to geographic locations.

Main outcome measure(s): Differences in sperm parameters.

Result(s): The semen volume was significantly lower in samples from Asia and Africa than in other regions. The sperm concentration was the lowest in Africa and highest in Australia. The total motile sperm count (TMSC) and total motile progressive sperm count (TMPS) were significantly lower in Africa than in other regions. The TMSC and TMPS in Asia and the United States were significantly lower than in Europe and Australia. The 5th percentile of the sperm concentration was lowest in the United States (12.5 × 10⁶/mL). The 5th percentile for the normal sperm morphology was lowest in the United States (3%) and highest in Asia (5%). The 5th percentile for the TMSC and TMPS were lowest in Africa (TMSC, 15.08 million; TMPS, 12.06 million) and the United States (TMSC, 18.05 million; TMPS, 16.86 million) and highest in Australia (TMSC, 29.61 million; TMPS, 25.80 million).

Conclusion(s): Significant geographic differences in sperm parameters exist, and regional fertility societies should consider adding their own reference ranges on the basis of local experience and treatment outcomes.

Keywords: Male infertility; andrology; computer-assisted sperm analysis (CASA); semen analysis; sperm quality.