The Handball World Championships are organised by the International Handball Federation (IHF). Competitor groups in the junior and youth categories are based on the assignment of athletes born in two consecutive years to the same category, with the cut coming at those born in an even-numbered year who thus have to remain in the same category for two years. The sample comprised 1,049 women handball players who played in the World Championship in their category, held in 2009 in the senior category and in 2010 in junior and youth categories. The variables were year of birth, gender and level of competition.The study took as a reference point whether the athlete was born in an odd- or even-numbered year. The differences between the proportion of athletes born in an even-numbered year or an odd-numbered year were calculated using the binomial test contrasting the proportion with 50\u2009%. There were no significant differences in the senior categories. In the junior and youth category more players were born in even-numbered years than in odd-numbered years, with very significant differences.<\/p>\n\n