{
  "slug": "global-sperm-count",
  "kind": "global-sperm-count",
  "eyebrow": "Graphs · Decline curve",
  "title": "Global Sperm Concentration, 1973–2018 (with trend projection)",
  "source": "Levine et al. 2023 · Human Reproduction Update",
  "sourceUrl": "https://academic.oup.com/humupd/article/29/2/157/6824414",
  "dataYear": "2023",
  "updated": "May 2026",
  "unit": "million per milliliter",
  "_dataNote": "Source: Levine et al. 2023 (Human Reproduction Update). Rates use the paper's reported acceleration ratio (1.16/2.64 ≈ 2.17×) scaled to land at the paper's reported 2018 endpoint of 49.0 M/mL, accounting for rounding in the published headline rates. Annual values are model output, not direct measurements. The 2019-2050 projection is an extrapolation assuming continuation of the post-2000 decline rate; it is not from the paper.",
  "frame": "Sperm concentration in men globally, 1973 to 2018, from the Levine et al. 2023 meta-analysis. The decline rate doubled after 2000: roughly 1 percent per year for the first 27 years, then more than double that pace through 2018. The dashed line extends the post-2000 rate forward as a projection.",
  "stats": [
    { "value": "101", "caption": "Concentration in 1973 (M/mL)" },
    { "value": "49", "caption": "Concentration in 2018 (M/mL)" },
    { "value": "23", "caption": "Projected concentration in 2050 (M/mL)" }
  ],
  "methodology": "Compiled from Levine et al. (2023), a systematic review and meta-regression of 223 sperm-concentration studies covering 1973–2018, published in Human Reproduction Update. The paper reports a biphasic decline with the post-2000 rate roughly 2.17× the pre-2000 rate. The curve here applies that acceleration ratio at rates of 1.09%/yr (1973–2000) and 2.36%/yr (2000–2018), scaled so the model lands at the paper's reported 2018 endpoint of 49.0 M/mL (the paper's published rounded rates of 1.16% and 2.64% compound to ~45.5, slightly below the reported endpoint due to rounding). The shaded band on the projection portion is illustrative, widening from ±15 percent at 2019 to ±25 percent at 2050. The WHO 2010 lower reference limit (5th percentile of fertile-male distribution) is 15 M/mL.",
  "annotations": {
    "whoThreshold": 15,
    "whoThresholdLabel": "WHO 5th percentile reference (15 M/mL)"
  },
  "historical": [
    { "year": 1973, "value": 101.20 },
    { "year": 1974, "value": 100.10 },
    { "year": 1975, "value": 99.01 },
    { "year": 1976, "value": 97.93 },
    { "year": 1977, "value": 96.86 },
    { "year": 1978, "value": 95.81 },
    { "year": 1979, "value": 94.76 },
    { "year": 1980, "value": 93.73 },
    { "year": 1981, "value": 92.71 },
    { "year": 1982, "value": 91.70 },
    { "year": 1983, "value": 90.70 },
    { "year": 1984, "value": 89.71 },
    { "year": 1985, "value": 88.73 },
    { "year": 1986, "value": 87.77 },
    { "year": 1987, "value": 86.81 },
    { "year": 1988, "value": 85.87 },
    { "year": 1989, "value": 84.93 },
    { "year": 1990, "value": 84.01 },
    { "year": 1991, "value": 83.09 },
    { "year": 1992, "value": 82.18 },
    { "year": 1993, "value": 81.29 },
    { "year": 1994, "value": 80.40 },
    { "year": 1995, "value": 79.52 },
    { "year": 1996, "value": 78.65 },
    { "year": 1997, "value": 77.79 },
    { "year": 1998, "value": 76.94 },
    { "year": 1999, "value": 76.10 },
    { "year": 2000, "value": 75.27 },
    { "year": 2001, "value": 73.49 },
    { "year": 2002, "value": 71.76 },
    { "year": 2003, "value": 70.06 },
    { "year": 2004, "value": 68.41 },
    { "year": 2005, "value": 66.79 },
    { "year": 2006, "value": 65.21 },
    { "year": 2007, "value": 63.67 },
    { "year": 2008, "value": 62.17 },
    { "year": 2009, "value": 60.70 },
    { "year": 2010, "value": 59.27 },
    { "year": 2011, "value": 57.87 },
    { "year": 2012, "value": 56.51 },
    { "year": 2013, "value": 55.17 },
    { "year": 2014, "value": 53.87 },
    { "year": 2015, "value": 52.60 },
    { "year": 2016, "value": 51.36 },
    { "year": 2017, "value": 50.15 },
    { "year": 2018, "value": 48.97 }
  ],
  "projection": [
    { "year": 2018, "value": 48.97, "lower": 48.97, "upper": 48.97 },
    { "year": 2019, "value": 47.82, "lower": 40.65, "upper": 54.99 },
    { "year": 2020, "value": 46.69, "lower": 39.54, "upper": 53.84 },
    { "year": 2021, "value": 45.59, "lower": 38.46, "upper": 52.72 },
    { "year": 2022, "value": 44.51, "lower": 37.40, "upper": 51.62 },
    { "year": 2023, "value": 43.46, "lower": 36.38, "upper": 50.54 },
    { "year": 2024, "value": 42.43, "lower": 35.38, "upper": 49.48 },
    { "year": 2025, "value": 41.43, "lower": 34.41, "upper": 48.45 },
    { "year": 2026, "value": 40.46, "lower": 33.48, "upper": 47.44 },
    { "year": 2027, "value": 39.50, "lower": 32.56, "upper": 46.44 },
    { "year": 2028, "value": 38.57, "lower": 31.67, "upper": 45.47 },
    { "year": 2029, "value": 37.66, "lower": 30.80, "upper": 44.52 },
    { "year": 2030, "value": 36.77, "lower": 29.95, "upper": 43.59 },
    { "year": 2031, "value": 35.90, "lower": 29.13, "upper": 42.67 },
    { "year": 2032, "value": 35.05, "lower": 28.32, "upper": 41.78 },
    { "year": 2033, "value": 34.22, "lower": 27.54, "upper": 40.90 },
    { "year": 2034, "value": 33.41, "lower": 26.78, "upper": 40.04 },
    { "year": 2035, "value": 32.62, "lower": 26.04, "upper": 39.20 },
    { "year": 2036, "value": 31.85, "lower": 25.33, "upper": 38.37 },
    { "year": 2037, "value": 31.10, "lower": 24.63, "upper": 37.57 },
    { "year": 2038, "value": 30.37, "lower": 23.95, "upper": 36.79 },
    { "year": 2039, "value": 29.65, "lower": 23.29, "upper": 36.01 },
    { "year": 2040, "value": 28.95, "lower": 22.65, "upper": 35.25 },
    { "year": 2041, "value": 28.27, "lower": 22.02, "upper": 34.52 },
    { "year": 2042, "value": 27.60, "lower": 21.41, "upper": 33.79 },
    { "year": 2043, "value": 26.95, "lower": 20.82, "upper": 33.08 },
    { "year": 2044, "value": 26.32, "lower": 20.25, "upper": 32.39 },
    { "year": 2045, "value": 25.70, "lower": 19.69, "upper": 31.71 },
    { "year": 2046, "value": 25.09, "lower": 19.14, "upper": 31.04 },
    { "year": 2047, "value": 24.50, "lower": 18.61, "upper": 30.39 },
    { "year": 2048, "value": 23.92, "lower": 18.10, "upper": 29.74 },
    { "year": 2049, "value": 23.35, "lower": 17.59, "upper": 29.11 },
    { "year": 2050, "value": 22.80, "lower": 17.10, "upper": 28.50 }
  ]
}