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A public health emergency

The Silent Crisis

Global sperm counts have halved in under 50 years. The decline is accelerating.

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The Evidence at a Glance

Data drawn from meta-analyses of hundreds of studies spanning five decades.

51.6%
Decline in global sperm concentration between 1973 and 2018
Levine et al., Human Reproduction Update (2023)
2.64%
Annual decline rate post-2000 — double the 1.16% rate pre-2000
Levine et al., Human Reproduction Update (2023)
~49M/mL
Current average sperm concentration, down from ~99M/mL in 1973
Levine et al., 2017 & 2023 meta-analyses (2023)
15M/mL
WHO threshold for "normal" sperm concentration
WHO Laboratory Manual, 6th Edition (2021)

Why This Matters

Sperm count is not merely a measure of fertility — research links it to broader indicators of male health, including cardiovascular risk, metabolic disease, and overall mortality. The decline is a canary in the coal mine for environmental and public health.

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Featured Research

Key studies and reports driving our understanding of male reproductive decline.

Temporal trends in sperm count: a systematic review and meta-regression analysis (2023 update) — Human Reproduction Update 1 Mar 2023 Temporal trends in sperm count: a systematic review and meta-regression analysis (2017) — Human Reproduction Update 1 Nov 2017 Sperm concentration remains stable among fertile American men (2025) — Fertility and Sterility 1 Jan 2025

Latest Analysis

Commentary and deeper dives into the research.