Claim: Men in 1970 Had Twice the Sperm Count of Teenagers Today

Verdict: Possibly true, but misleading

“We have, as Dr. Oz pointed out, a fertility crisis in this country right now. We just found out that we've dropped out of 1.57 percent. […] The fertility crisis for women began in 2007. For men: in 1970, men had twice the sperm count, as our teenagers do today.”

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RFK Jr. spoke about the fertility crisis last week at a maternal health event in the White House, and in the process made this bizarre-sounding claim about male sperm counts. Is it true? Is this what we should focus on in the fertility crisis?

What RFK Jr’s Source Actually Says

RFK Jr’s comment is specifically in reference to this meta-analysis, which compares sperm counts for men in various global regions between 1973 and 2018.

His comment is broadly in line with the results of the study. The researchers found that men from North America, Europe and Australia had seen roughly 50% declines in sperm count from 1973 to 2018.  

Note two things:

1. The study didn’t only look at Americans – US data was combined with other regions.

2. The study didn’t look at teens specifically; the data wasn’t broken down by age.

Based on the analysis, the lowest possible sperm count for North American men would be around 46 million per millilitre. However, the paper also notes that beyond a threshold value of somewhere around 40-50 million/ml, a higher sperm count doesn’t necessarily mean you’re more likely to conceive.

Other Papers Don’t Agree

Another meta-analysis directly challenged the results above, focusing on just the U.S. and finding that there is no significant decline in sperm concentration for men without known infertility. The authors note that results like the one above may have been biased by infertile people, subfertile people and people at risk of infertility, while in other men, there is no difference.  

The U.S. Fertility Crisis and Sperm Count

There are many factors causing the decline in fertility across much of the world, mainly cultural in nature (for example, expanding reproductive rights) or simply a result of less childhood mortality. The problem exists throughout Europe, parts of Asia and Australia too, and in fact even Canada has lower fertility than the U.S..

Sperm counts have declined, but they are not the primary reason for the fertility crisis.