Trends have shown a significant decline in sperm counts between 50 and 60 percent among men from North America, Europe, and Australia from 1973 to 2011, according to a study published in Human Reproduction Update.
Hagai Levine, PhD, from the Braun School of Public Health and Community Medicine at Hadassah-Hebrew University in Jerusalem, and colleagues conducted a systematic review and meta-regression analysis of recent trends in sperm count as measured by sperm concentration (SC) and total sperm count (TSC), and their modification by fertility and geographic group. The authors searched PubMed/MEDLINE and EMBASE for English-language studies of male SC published from 1981 to 2013.
Eligibility criteria included fertility group (Unselected by fertility vs Fertile), geographic group (Western, including North America, Europe, Australia, and New Zealand vs Other, including South America, Asia, and Africa), age, ejaculation abstinence time, semen collection method, method of measuring SC, and semen volume.
A total of 244 estimates of SC and TSC from 185 studies of 42,935 men who provided semen samples from 1973 to 2011 were extracted for meta-regression analysis, as well as information on years of sample collection and covariates. Data were found from 6 continents and 50 countries. The mean SC was 81 million/ml, the mean TSC was 260 million, and the mean year of data sample collection was 1995. Of the 244 estimates, 110 (45%) were Unselected Western, 65 (27%) Fertile Western, 30 (12%) Unselected Other, and 39 (16%) Fertile Other.
A significant decline in SC was found among Unselected Western (−1.38) and among Fertile Western (−0.68) men, while no significant trends were seen among Unselected Other and Fertile Other men. Among Unselected Western studies, the mean SC declined, on average, 1.4% per year with an overall decline of 52.4%. Trends for TSC and SC were similar, with a decline among Unselected Western men (−5.33 million/year) corresponding to an average decline in mean TSC of 1.6% per year and overall decline of 59.3%.
“In this comprehensive meta-analysis, sperm counts whether measured by SC or TSC declined significantly among men from North America, Europe and Australia during 1973–2011, with a 50–60% decline among men unselected by fertility, with no evidence of a ‘leveling off’ in recent years,” the authors concluded.
- Levine H, Jørgensen N, Martino-Andrade A, et al. Temporal trends in sperm count: a systematic review and meta-regression analysis. Hum Reprod Update. 25 July 2017. https://doi.org/10.1093/humupd/dmx022