A Relative Age Effect (RAE), by which young athletes with birthdates early in a calendar year have experienced a team selection advantage that persists throughout their careers, has been found to be prevalent in many sports. However, this phenomenon has not been investigated in the Paralympic sports context. Thus, we aimed to investigate the prevalence of RAE among male and female Brazilian Paralympic swimmers. Data from 694 ranked athletes were collected from the 2021 Brazilian Paralympic Swimmers National rankings. Athletes' birthdates were divided into four quarters (Q1, Q2, Q3, and Q4) according to their month of birth. Chi-Square (χ2) goodness-of-fit tests were used to compare the observed and expected distributions of athletes born in each quarter, based on sex (male and female), impairment type (physical, visual, and intellectual), and swim stroke competition (freestyle, medley, backstroke, butterfly, and breaststroke). The observed birthdates distributions were different from expected in males (χ2 = 11.647; p = 0.009) and females (χ2 = 8.899; p = 0.031), for athletes with physical impairments (χ2 = 10.443; p = 0.015); and for athletes who competed in freestyle (χ2 = 16.683; p = 0.001), medley (χ2 = 12.343; p = 0.006) and backstroke (χ2 = 8.025; p = 0.045) races. Even though our results demonstrated asymmetric distributions of Brazilian Paralympic swimmers' birthdates in many of the analyses, we could not establish the classical prevalence of athletes born at the beginning of the year that defines RAE. Therefore, the selection process of Brazilian Paralympic swimmers does not seem to be influenced by the athletes' time of birth.
Keywords: adaptive sport; age-related effect; athlete selection; atypical distribution; swimming.