![\"\"](\"https:\/\/cdn.factcheck.org\/UploadedFiles\/Sperm-720-x-307.png\")
<\/p>\n<\/p>\n
Health and Human Services Secretary Robert F. Kennedy Jr. has baselessly tied alleged declines in sperm counts among teenagers to a \u201cfertility crisis\u201d or an \u201cexplosion in infertility.\u201d<\/p>\n
There is very little data on sperm counts in teenagers, and there\u2019s mixed evidence on whether they have changed over time in adults. Regardless, experts told us there isn\u2019t reason to believe declining sperm counts are causing the falling rate of childbirths in the U.S., which has more plausible social and behavioral explanations.<\/p>\n
On at least<\/a> a dozen occasions<\/a> since becoming<\/a> HHS secretary<\/a>, Kennedy<\/a> has claimed<\/a> there has been<\/a> a dramatic drop<\/a> in sperm counts<\/a>, saying<\/a> it\u2019s evidence of a health crisis. His interest<\/a> in this topic<\/a> goes back nearly a decade<\/a>.<\/p>\n \u201cMale sperm counts, I think, in this country are down 50% for teenage males,\u201d he said<\/a> on a May 28 episode of his recently launched podcast, after introducing concerns about a \u201cstunning\u201d drop in the rate of childbirths. \u201cI read the other day that teenage males today have less sperm than the average 65-year-old American man.\u201d At a May 11 event at the White House, he discussed<\/a> statistics on childbirths, while also claiming a \u201cfertility crisis\u201d involving falling sperm counts in teens. \u201cThis is an existential crisis for our country,\u201d he said.<\/p>\n Contrary to Kennedy\u2019s statements, there is very little data about sperm counts in teenagers in the scientific literature at all. The studies establishing sperm counts in healthy adolescents have \u201cnever been done,\u201d\u00a0Dolores Lamb<\/a>, who studies male reproductive biology and urology at Children\u2019s Mercy Kansas City, told us.<\/p>\n There are some studies<\/a> that have found<\/a> about a 50% drop in sperm counts in men over the past half century or so. Kennedy has linked to this research<\/a> or coverage<\/a> of it multiple<\/a> times on X. HHS has previously<\/a> cited these 2017 and 2023 studies to support Kennedy\u2019s claims, although the agency did not respond to our request for comment.<\/p>\n But other studies have not found<\/a> such declines<\/a>, and comparisons to the past are complicated by inconsistencies in how sperm is counted. \u201cI would argue that we don\u2019t yet have consensus,\u201d Allan Pacey<\/a>, a professor of andrology at the University of Manchester, told us. <\/p>\n In any case, sperm declines are not likely to be a driving factor in today\u2019s falling childbirth rates, experts said.<\/p>\n \u201cDeclining sperm count are expected to impact population birth rates significantly only at very advanced stage, as men have multiple opportunities to [conceive],\u201d Dr. Hagai Levine<\/a>, an epidemiologist and public health physician at Hebrew University-Hadassah School of Public Health who co-authored the studies HHS cited, told us in an email, even as he said that in his view, the \u201cstrong decline does indicate that there is a problem.\u201d<\/p>\n Alison Gemmill<\/a>, a reproductive epidemiologist and demographer at the University of California, Los Angeles, told us that Kennedy is erroneously conflating the falling fertility rate with a decline in people\u2019s biological ability to conceive. The rate of childbirths has indeed fallen, she said, but it has been driven by a drop in birth among teenagers and women in their 20s.<\/p>\n \u201cWhat\u2019s going on with people in their teens and 20s is they\u2019re just waiting longer to have kids, and they\u2019re using more effective contraception, and they\u2019re having fewer unintended or unwanted births,\u201d she said. \u201cSo, I think the overwhelming majority of evidence points to social and behavioral changes rather than biological changes.\u201d<\/p>\n Nor has there been a recent \u201cexplosion,\u201d as Kennedy said, in infertility by its medical definition, Katherine Tierney<\/a>, an assistant professor in the department of sociology at Western Michigan University, told us in an email. While the fertility rate reflects the rate of childbirths in the population, infertility refers<\/a> to difficulty becoming pregnant.<\/p>\n \u201c[T]he prevalence of medically-defined infertility in the U.S. has remained fairly stable over time, despite the decline in fertility, which calls into question the proposal that rising infertility is a major driver of the fertility decline,\u201d Tierney said, based<\/a> on survey<\/a> data<\/a> from<\/a> the Centers for Disease Control and Prevention.<\/p>\n There has been\u00a0controversy<\/a>\u00a0for decades about whether sperm counts in the population are falling.<\/p>\n In 1992, Danish researchers pulled together the available data and did a meta-analysis<\/a>, a type of study that combines data from multiple past studies on a topic. The researchers concluded that sperm concentration had dropped by more than 40% between 1940 and 1990. (The term sperm count encompasses<\/a> two related measures: sperm concentration, or the amount of sperm per milliliter of semen, and total sperm count, or the number of sperm per ejaculate.)<\/p>\n Shanna Swan<\/a>, an environmental reproductive epidemiologist at Icahn School of Medicine at Mount Sinai, told us in an email that the 1992 study was \u201cvery strong,\u201d adding that it was \u201cfurther strengthened\u201d by a reanalysis of the data she published<\/a> five years later. She and her co-authors found an \u201ceven steeper\u201d decline in sperm counts in the U.S. and Europe, according to the study. (Swan went on to co-author the more recent studies with Levine that showed a decline in sperm count.)<\/p>\n But Lamb criticized the 1992 study for including relatively little data from the early years of the covered period, among other issues, and said that the authors \u201cassume that the data that\u2019s published in these papers is accurate and precise.\u201d\u00a0<\/p>\n In fact, sperm is quite challenging to count, Lamb and Pacey told us.<\/p>\n During much of this study period there was little standardization<\/a> of sperm counting, Pacey explained in an editorial in 2013. The World Health Organization came out with guidelines in 1980, followed by multiple revisions. But even after this, studies showed<\/a> that many labs did not follow the guidelines and that there was substantial variation between labs in counts even when they all looked at the same sample.<\/p>\n Ejaculate is a mixture of fluids from different glands, Pacey said. \u201cIt\u2019s a viscous fluid, so it\u2019s very difficult to pipette,\u201d he explained, and there are multiple steps in sperm analysis that can introduce errors.<\/p>\n Lamb said that people are supposed to count sperm in\u00a0specialized glass chambers<\/a>\u00a0with a grid after diluting semen and preventing sperm from moving. But labs may instead use disposable chambers to avoid cleaning or fail to properly immobilize the sperm.<\/p>\n Pacey said that he chairs a U.K. advisory committee to a national sperm counting quality assurance program, and there\u2019s still \u201chuge variation\u201d among labs counting the same sample. \u201cThat makes me concerned about how accurate we are when we report [sperm count] in papers.\u201d\u00a0<\/p>\n Pacey added that sperm counts can also vary within even the same person depending on a variety of factors, such as length of time since last ejaculation and level of sexual stimulation, complicating analyses. And Lamb said that sperm count is a genetic trait and varies geographically. \u201cIt\u2019s just biology,\u201d and it\u2019s not that areas with lower sperm counts necessarily have more infertility, she said.<\/p>\n The\u00a02017<\/a>\u00a0and\u00a02023<\/a>\u00a0studies on sperm count from Swan and Levine looked at more recent data than the 1992 study, excluded studies reporting nonstandard methods, excluded men known to be infertile or with exposures implicated in infertility, and otherwise attempted to address prior criticisms.<\/p>\n Sperm counts have \u201cdeclined by 50-60% between 1973 to 2018, globally, including in North America (mainly US),\u201d Levine said.<\/p>\n Lamb said that the 2017 study\u2019s rigor had improved \u201ca little\u201d but said it still had issues, such as those related to counting sperm.<\/p>\n Despite even further improvements to the 2023 study, which added new data and analyses, \u201cpoor data is still poor data,\u201d Lamb said. She added that the authors do not take into account \u201cmethodological issues and lack of standardization for semen analysis performance and change in methods over the years.\u201d<\/p>\n Another 2023 meta-analysis<\/a> by different researchers looking at studies on sperm count in the U.S. and Western Europe between 1993 and 2018 did not find a significant change over this period, including when looking specifically at the U.S.<\/p>\n A 2025 meta-analysis<\/a> by yet another group also reviewed the U.S. sperm count literature, finding what the authors called \u201cremarkably stable\u201d sperm counts from 1970 to 2018. The researchers generally found no change or increases in various measures of sperm count, with the exception of a decline in sperm concentration, after adjusting for region and fertility status, that was \u201cless than half the annual decline that has been observed in previous global meta-analyses,\u201d the authors wrote.<\/p>\n Pacey said that results from different meta-analyses can vary due to differences in methods and the time period and populations covered. Lamb said the 2025 paper was particularly well done, explaining that it excluded many studies that did not meet its \u201ccriteria for rigor, strong experimental design, original data, sample number, etc.\u201d<\/p>\n When three different large meta-analyses are \u201ctelling you different things, I would argue we don\u2019t have consensus,\u201d Pacey said, adding that people like Kennedy \u201ckind of cherry-pick the data to suit the argument that they\u2019re making at the time.\u201d\u00a0<\/p>\n Regardless, Pacey said, one wouldn\u2019t expect the level of sperm decline that studies have reported to make a major contribution to falling birth rates. \u201cIt\u2019s still a decline from normal to normal on average,\u201d he said.\u00a0<\/p>\n \u201cWhen we look at studies that are more well done, there is potentially evidence of a decline, especially a long-term decline,\u201d Gemmill said of the sperm count literature. \u201cBut the main takeaway is that when we think of this measure of sperm count, it\u2019s still at levels that we don\u2019t think it\u2019s going to really make an impact on people\u2019s ability to conceive.\u201d<\/p>\n Kennedy has repeatedly compared today\u2019s teenagers to older men, claiming<\/a> that \u201cthe fertility of our kids is down\u201d and that teens have half the sperm count of a 68-year-old<\/a>, 65-year-old<\/a> or 60-year-old<\/a> man. <\/p>\n \u201cWe\u2019re seeing an explosion in infertility,\u201d he said at an event<\/a> in West Virginia in March 2025, for example. \u201cTeenagers today have 50% of the sperm count\u201d of 68-year-old men, he added.<\/p>\n Despite this rhetoric, there simply aren\u2019t data on sperm counts comparing teens from the general population to men in their 60s.<\/p>\n \u201cThe studies on that directly have not been done,\u201d Lamb said, because the panels that review studies with human subjects for institutions are not going to \u201chave parents consent for their boys to masturbate to collect semen samples\u201d in a clinic.<\/p>\n Measures such as total sperm count and volume decline<\/a> as men age<\/a>.<\/p>\n There are limited data looking at sperm counts in adolescents with health problems who have given semen samples. Lamb was involved in one study<\/a> that compared sperm counts in adolescents and adults who were storing sperm samples prior to cancer treatment that might damage their fertility. The study found slightly lower sperm counts in the younger age group than in the adults.<\/p>\n But Lamb said that this study was not meant to establish normal sperm counts for adolescents, but rather to better understand what very young patients undergoing fertility preservation might expect. \u201cThe important thing to realize is these boys were seriously ill,\u201d she said, and their sperm counts cannot be taken as representative.<\/p>\n There have also been comparisons<\/a> of data on sperm counts in young men being considered for military service, some of them technically teenagers, and those of somewhat older men. Researchers in Denmark \u2014 some of whom had co-authored the 1992 paper showing falling sperm counts \u2014 tracked sperm counts from young men presenting for medical examination with a median age of 19 between 1996 and 2010. They found these young adults\u2019 sperm counts were lower than those of two groups: sperm counts collected between 1996 and 1998 from men whose partners were pregnant, and sperm counts from 1939 to 1943 in men who were part of infertile couples.<\/p>\n The men in the comparison groups were largely in their 20s and 30s, and not in their 60s. But the authors of the study did raise concerns about a generational decline, writing that \u201cthere is reason to be concerned about future fertility of young Danish men.\u201d However, the study showed that sperm counts in successive groups of young men presenting for examination rose over the 15 years of the study. <\/p>\n \u201cIf you want to do the best study possible, you would do a prospective study where you would actively go out and recruit new cohorts of men every year of a similar age and a similar lifestyle and a similar demographic, and you would follow them over time to see whether sperm counts were declining,\u201d Pacey said. That is what the Danish study did in looking at potential military recruits. And this didn\u2019t show falling sperm counts, he said.<\/p>\n Meanwhile, he said he thought the researchers \u201coverinterpreted\u201d their data on young potential recruits in going back and comparing it to data collected on different groups of men. \u201cIf retrospective data is showing one thing and prospective data is showing another, that suggests we have a data problem rather than a biology problem,\u201d he said, adding that he doesn\u2019t think \u201cthe study is a sign of a reduction in sperm quality in young men.\u201d<\/p>\n Regardless of the trends in sperm counts, demographers said there are other factors that are likely leading people to have fewer children, despite Kennedy repeatedly connecting it to falling sperm count or infertility.<\/p>\n \u201cWe have fertility rates that are just spiraling,\u201d he told<\/a> Jesse Watters during a Fox News interview in April 2025, going on to reference a 50% drop in sperm counts. \u201cThe fertility rate is plummeting,\u201d he said<\/a> at a June 2025 press conference, again mentioning a halving of sperm counts.<\/p>\n \u201cThere\u2019s no particular reason to think that physiological factors would be a big cause of [falling birth rates], when we know there\u2019s lots of social factors that could be contributing,\u201d Sarah Hayford<\/a>, director of the Institute for Population Research at Ohio State University, told us.<\/p>\n She said that broadly speaking, birth rates have been falling for 150 years in high-income countries. In the U.S., there was a decline in the 1970s after the Baby Boom, followed by \u201cpretty stable\u201d birth rates through the early 2000s, supported by a relatively high teen birth rate compared with other high-income countries. Birth rates again declined during the Great Recession in 2007 to 2009 and, unexpectedly to demographers, continued to fall, primarily driven by declines in births to teens and young adults in their early 20s, particularly among unmarried<\/a> people. <\/p>\n Fertility rates are measured in various<\/a> ways, but one way is to estimate how many babies a woman on average would have over her lifetime using the current birth rates for various age groups of women, or what\u2019s called the total fertility rate. By this measure, the fertility rate in 2024 fell to a low of 1.6 per woman, according to CDC data. Provisional CDC data<\/a> on birth rates from 2025 indicate they continued to fall.<\/p>\n Kennedy has appeared<\/a> to refer to these CDC statistics, as well as<\/a> to Social Security Administration estimates<\/a> of total fertility rates, when referring to the falling fertility rate.<\/p>\n \u201cWhen my uncle was president, the fertility rate in this country was 3.5%,\u201d he said at an October 2025 White House event<\/a> on fertility treatment. \u201cToday it is 1.6%.\u201d He then claimed the average U.S. teenager has half the sperm count of a 65-year-old man.<\/p>\n Hayford said that there are likely multiple social and behavioral changes working together to impact birth rates since the Great Recession. For teens<\/a>, she said, \u201cit seems pretty clear that that\u2019s about increased contraceptive use,\u201d particularly long-acting methods such as IUDs and implants.<\/p>\n Meanwhile, economic and other factors have affected people\u2019s choices around childbearing.<\/p>\n One possible factor is a sense of economic insecurity that never fully dissipated after the Great Recession, despite macroeconomic recovery, Hayford said. There has also been a decline in the rates at which people get married, she added.<\/p>\n \u201cGlobal uncertainty has increased, and just general uncertainty about the future,\u201d UCLA\u2019s Gemmill said. \u201dWe\u2019ve seen study after study show that that is also tied to decisions and ambivalence about having children.\u201d\u00a0<\/p>\n Gemmill added that studies have shown a rise in \u201cintensive parenting,\u201d or the idea that people feel \u201cthey need to give a lot more or \u2026 have more resources to support raising children in the United States.\u201d At the same time, people are experiencing economic challenges in the housing market, the price of childcare and the availability of paid family leave, she said.<\/p>\n There\u2019s also a trend toward people staying in school longer and getting more education, Hayford said.<\/p>\n In periods where people are shifting when they have children to later in life, the total fertility rate<\/a> will likely underestimate the number of children women will have by the end of their childbearing years, Hayford said, as some people might \u201ccatch up.\u201d<\/p>\n At the same time, delaying childbearing does tend to lead to a lower total number of children, as people are \u201cmore likely to run into problems\u201d with their fertility, Hayford said. People also tend to \u201creduce their fertility intentions as they get older\u201d based on the other things going on in their lives, she explained.<\/p>\n But apart from age-related declines in the biological ability to bear children, experts pushed back against the idea that there\u2019s been a major rise in infertility, or the rate at which people have trouble becoming pregnant.<\/p>\n For one thing, Hayford said, the fact that declines in the fertility rate are concentrated in unmarried people \u201cis an indicator that it\u2019s probably not physiological processes going on.\u201d If there were some chemical exposure \u201cthat was reducing fertility, you would expect to see that among married people as well as among unmarried people,\u201d she said.\u00a0\u00a0<\/p>\n Furthermore, the data that are available on infertility in the U.S. do not indicate any major rise.<\/p>\n It is \u201cvery hard\u201d to measure the biological capacity for childbearing over time, Gemmill said. However, when researchers have attempted to track the rate of Americans meeting the medical definition of infertility, \u201cthere\u2019s not really much change,\u201d she said, referring to the CDC\u2019s National Survey of Family Growth.<\/p>\n Several studies using these data have looked at the rate of infertility \u2014 defined as no pregnancy following 12 months of regular, unprotected intercourse \u2014 among married and cohabiting women. The studies found no significant<\/a> change between<\/a> 1995 and 2019 or, in one case<\/a>, a small rise between the first and second half of the 2010s.<\/p>\n Another study<\/a> using this dataset looked at how long women reported trying to become pregnant, finding no significant change overall between 2002 and 2017. The time to pregnancy slightly increased over time for women who had prior children and women over 30.<\/p>\n The fact that both measures of infertility used in these papers \u201cshow no or little change in medically-defined infertility offers strong evidence against the idea of an infertility \u2018explosion,\u2019\u201d Tierney said, despite increases<\/a> in the rate<\/a> at which people seek treatment for infertility and a small increase<\/a> in people\u2019s perceptions that they are infertile.<\/p>\n None of this is to dismiss the importance of better understanding infertility and reproductive health, Gemmill said.<\/p>\n \u201cI fully think that we need more research on environmental contaminants and sperm and reproductive health conditions,\u201d she said. \u201cBut I don\u2019t think it\u2019s at the level \u2014 at least based on the human studies that I\u2019ve seen \u2014 where it\u2019s going to impact birth rates at a population level. What is happening in the U.S. right now is because of social change.\u201d<\/p>\n Editor\u2019s note:\u00a0FactCheck.org does not accept advertising. We rely on grants and individual donations from people like you. Please consider a donation. Credit card donations may be made through\u00a0our \u201cDonate\u201d page<\/a>. If you prefer to give by check, send to: FactCheck.org, Annenberg Public Policy Center, P.O. Box 58100, Philadelphia, PA 19102.\u00a0<\/em><\/p>\n The post RFK Jr.\u2019s Flawed Claims About Sperm Count and Fertility<\/a> appeared first on FactCheck.org<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":" Health and Human Services Secretary Robert F. Kennedy Jr. has baselessly tied alleged declines in sperm counts among teenagers to a \u201cfertility crisis\u201d or an \u201cexplosion in infertility.\u201d There is very little data on sperm counts in teenagers, and there\u2019s mixed evidence on whether they have changed over time in adults. Regardless, experts told us […]<\/p>\n","protected":false},"author":6,"featured_media":69675,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"tdm_status":"","tdm_grid_status":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-69674","post","type-post","status-publish","format-standard","has-post-thumbnail","category-factcheck"],"_links":{"self":[{"href":"https:\/\/diaspora.biz\/index.php?rest_route=\/wp\/v2\/posts\/69674","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/diaspora.biz\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/diaspora.biz\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/diaspora.biz\/index.php?rest_route=\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/diaspora.biz\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=69674"}],"version-history":[{"count":0,"href":"https:\/\/diaspora.biz\/index.php?rest_route=\/wp\/v2\/posts\/69674\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/diaspora.biz\/index.php?rest_route=\/wp\/v2\/media\/69675"}],"wp:attachment":[{"href":"https:\/\/diaspora.biz\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=69674"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/diaspora.biz\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=69674"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/diaspora.biz\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=69674"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n![\"\"\/](\"https:\/\/cdn.factcheck.org\/UploadedFiles\/SciCHECKsquare_4-161x145.png\")
<\/figure>\n<\/div>\nUncertainty About Sperm Count Over Time<\/strong><\/h2>\n
\n![\"\"](\"https:\/\/cdn.factcheck.org\/UploadedFiles\/Sperm-400-x-267.png\")
A Lack of Evidence for Teen Comparisons<\/strong><\/h2>\n
Why Are People Having Fewer Children?<\/h2>\n
\n