About 1 in 13 Black or African American babies is born with sickle cell trait, the carrier state for sickle cell disease, according to the CDC's primary data on sickle cell trait. The 2025 background to a US military medical-records cohort study independently confirmed the rate at "1 in 13 births in Black and African American families" (Phillips et al., AJOG Global Reports 2025; PMID 40336904).
Sickle cell trait is not sickle cell disease. Trait carriers inherit one sickle hemoglobin gene and one normal hemoglobin gene; they almost never have symptoms in everyday life. Two trait carriers who have a child together pass the disease to that child with one-in-four probability per pregnancy. Most Black children with sickle cell trait will go through life unaware of their carrier status unless an athletic, military, or surgical setting asks the question.
The setting where the question gets asked most often is collegiate athletics. The NCAA has required sickle cell trait status confirmation before Division I, II, and III participation since August 2010, after a decade in which 10 of 16 conditioning deaths in NCAA Division I football were associated with the trait, an excess of up to 21-fold (Eichner, Current Sports Medicine Reports 2010; PMID 21068567). The policy responded to a recognized clinical problem with measurable consequences for Black football players.
After the policy, sickle-cell-trait-associated deaths in Black Division I football players fell from about 1 per 12,519 athlete-years to about 1 per 118,464 athlete-years, an 89 percent risk reduction (Buchanan et al., Sports Health 2020; PMID 32271134). Across all Division I football the figures fell from 1 per 28,145 to 1 per 250,468 athlete-years. The Buchanan team analyzed NCAA athlete-deaths data covering 8,309,050 athlete-years from 2000 through 2019.
The Buchanan paper is explicit about what the data cannot say. The authors write, verbatim: "It is unclear whether the decrease is related to screening for SCT, education, or both." The 2010 NCAA policy bundled mandatory screening with concurrent changes in conditioning protocols, hydration education, and heat-acclimatization rules. The literature has not isolated the screening contribution from the protocol changes that arrived alongside it.
What the evidence says about universal precautions
The largest controlled study of sickle cell trait and exertional risk in young Black adults, published in the New England Journal of Medicine in 2016 by D. Alan Nelson and colleagues, followed 47,944 Black US Army soldiers on active duty between January 2011 and December 2014 (Nelson et al., NEJM 2016; PMID 27518662). The Army during that period applied universal exertional-injury precautions to all soldiers regardless of trait status: hydration protocols, work-rest cycles, heat-acclimatization, and supervisor oversight of conditioning intensity. Under those precautions, soldiers with sickle cell trait and soldiers without it had essentially equivalent death risk. Trait status, under universal precautions, did not predict death.
The same analysis showed sickle cell trait was associated with about a 50 percent higher rate of exertional rhabdomyolysis, an effect similar in magnitude to the rhabdomyolysis-risk elevation that comes with tobacco use among soldiers in the same cohort.
The Nelson finding is the empirical anchor for an alternative policy framework: universal exertional precautions for all athletes regardless of sickle cell trait status. The American Society of Hematology has formally opposed mandatory NCAA screening and recommended universal precautions since 2012 (Ferrari et al., Journal of Genetic Counseling 2015; PMID 26040250). The objection is that mandatory genetic-status disclosure of a Mendelian recessive condition strongly associated with Black ancestry stigmatizes Black athletes; universal precautions, applied to everyone, would not.
A 2024 NCAA institutional-resources audit found the implementation gap is unevenly distributed. Across 60 NCAA institutions, Historically Black Colleges and Universities reported a 4.9 percent average sickle cell trait prevalence in their athlete population versus 1.1 percent at non-HBCU institutions, and HBCUs were four times more likely to rely on student-supplied screening results than non-HBCUs (52.5 percent vs 12.9 percent), suggesting institutional-resource gaps for direct on-site screening at the schools serving the highest-risk athlete population (Yeargin et al., Journal of Strength and Conditioning Research 2024; PMID 39073355). Division III reported a 68.3 percent waiver rate vs 16.9 percent at Division I. The pediatric and high-school tier, where most Black children first encounter organized athletics, sits below the Division III implementation floor.
What the 2019 military deaths showed
In 2019, a cluster of US military trainees died from exercise collapse associated with sickle cell trait. The Department of Defense convened a summit at the Consortium for Health and Military Performance at the Uniformed Services University in October 2019; the summit's published consensus framed sickle cell trait as "largely benign" and produced clinical-management guidance for exercise-collapse events (O'Connor et al., Current Sports Medicine Reports 2021; PMID 33395130). The 2019 deaths happened in a setting where universal precautions should have been applied but were not, the same failure mode the pre-2010 NCAA football conditioning deaths displayed. References to a "2019 NATA consensus" on sickle cell trait are misattributions; the October 2019 ECAST summit was a CHAMP / USU event under the Department of Defense, not a NATA position.
Six voices on the evidence layer
The published evidence base above is anchored by Jonathan A. Drezner, MD (University of Washington Center for Sports Cardiology, NCAA pre-post-legislation paper); Francis G. O'Connor, MD, MPH (Uniformed Services University CHAMP, 2019 ECAST summit consensus); Susan W. Yeargin, PhD (University of South Carolina Arnold School of Public Health, 2024 NCAA institutional-resources audit); E. Randy Eichner, MD (Oklahoma Health Sciences Center, canonical SCT-and-sports clinical voice); Lakshmanan Krishnamurti, MD (Yale School of Medicine Pediatric Hematology and Oncology Chief, NCAA SCT-screening ethical-policy analysis); and Vence Bonham, JD (NIH National Human Genome Research Institute Social and Behavioral Research Branch, genomic-counseling and carrier-status disclosure).
What the evidence does not yet tell us
No head-to-head trial has compared NCAA-style mandatory-screening-plus-education-plus-precautions against universal-precautions-only in real-world athletic settings. The post-2010 NCAA effect's contribution from screening versus education versus protocol changes has not been isolated; Buchanan and Drezner are explicit on this. The equivalent deaths-averted analysis for Divisions II and III, and for high-school and club programs where most Black children encounter organized sports, has not been published. The actionable path is what is documented now: precautions are protective; screening alone is not.
Three concrete things to ask, depending on who you are
For Black parents of children in high-school or club athletic programs. Ask whether the school has universal exertional precautions in place regardless of trait status: heat-acclimatization protocols, hydration mandates, work-rest cycles on conditioning days, supervisor oversight on high-exertion days, and emergency-action-plan training. Screening without those precautions is the weaker half of the policy.
For Black athletes already screened sickle cell trait positive. Ask your team trainer about the specific precautions in place during conditioning. Under universal precautions, Nelson 2016 NEJM shows your death risk is essentially equivalent to trait-negative peers; the precautions, not the trait disclosure, are the protective factor. A coach using your trait status to selectively benchsit or differentially restrict training is the stigmatization pattern the Ferrari 2015 analysis named.
For policy advocates working on state-level high-school screening policy. ASH's position against mandatory NCAA screening is the institutional anchor; the Sickle Cell Disease Association of America operates state-level chapters engaging with screening and genetic-counseling policy. Universal exertional precautions for all athletes, with genetic counseling available on request, is the framework the evidence best supports. The Black Health provider directory lists hematologists and sports-medicine clinicians for families seeking a provider comfortable discussing trait, counseling, or athletic clearance.
Update plan
We will update this piece when a head-to-head screening-vs-precautions trial completes, when deaths-averted data for Divisions II and III publishes, or when ASH, NATA, or the American Academy of Pediatrics changes the screening recommendation.
Citations
CDC Sickle Cell Trait Data: "About 1 in 13 Black or African American babies is born with sickle cell trait." cdc.gov/sickle-cell/data/sickle-cell-trait.html. Accessed 2026-05-08.
Phillips AK, Wilson C, Ahmed AE, Shet A, Bevans M. Venous thromboembolism with contraceptive use in females with sickle cell trait. AJOG Global Reports. 2025. PMID 40336904.
Eichner ER. Sickle cell trait in sports. Current Sports Medicine Reports. 2010;9(6):347-351. PMID 21068567.
Buchanan BK, Siebert DM, Zigman Suchsland ML, Drezner JA, Asif IM, O'Connor FG, Harmon KG. Sudden Death Associated With Sickle Cell Trait Before and After Mandatory Screening. Sports Health. 2020;12(3):241-245. PMID 32271134.
Nelson DA, Deuster PA, Carter R, Hill OT, Wolcott VL, Kurina LM. Sickle Cell Trait, Rhabdomyolysis, and Mortality among U.S. Army Soldiers. New England Journal of Medicine. 2016;375(5):435-442. PMID 27518662.
Ferrari R, Parker LS, Grubs RE, Krishnamurti L. Sickle Cell Trait Screening of Collegiate Athletes: Ethical Reasons for Program Reform. Journal of Genetic Counseling. 2015;24(6):873-887. PMID 26040250.
O'Connor FG, Franzos MA, Nye NS, Nelson DA, Shell D, Voss JD, et al. Summit on Exercise Collapse Associated with Sickle Cell Trait: Finding the "Way Ahead". Current Sports Medicine Reports. 2021;20(1):47-56. PMID 33395130.
Yeargin SW, Meyer CM, Hirschhorn RM, Lane AD, Arent SM, Haggard CR. Characterization of Health and Safety Resources for Athletes With Sickle Cell Trait at NCAA Institutions. Journal of Strength and Conditioning Research. 2024;38(11):1967-1973. PMID 39073355.
