Does Month of Birth Affect Speed and Quality of Transition from School to Work?

In most countries, children in the same grade can be up to 12 months apart in age, which represents a considerable relative age difference, particularly in the early years. A relative age effect has been frequently reported in the diagnosis and treatment of attention-deficit/hyperactivity disorder and, more rarely, in the diagnosis of other neurodevelopmental disorders. The relative age effect has never been studied for speech therapy, which is frequently prescribed to treat specific language and learning disorders. To quantify the association of relative age with the initiation of speech therapy. This cohort study used data from the French National Health Data System and included all children born in France between 2010 and 2016 from September of the year of their 5th birthday until July of the year of their 10th birthday or July 31, 2022 (end of study). Children were categorized according to month of birth. Risk of speech therapy initiation was estimated using Cox models adjusted for other known risk factors. In total, 4 188 985 children (mean [SD] age, 5.2 [0.3] years; 50.8% girls) were included. Speech therapy was initiated for 692 086 children (incidence rate, 53.1 per 1000 person-years, 54.5% boys) during a mean (SD) follow-up of 3.1 (1.6) years. Among children of the same schooling level, the risk of initiating speech therapy steadily increased according to quarter and month of birth, with adjusted hazard ratios of 1.51 (95% CI, 1.50-1.52) for children born in the last quarter vs the first quarter and 1.64 (95% CI, 1.62-1.66) for children born in December vs those born in January. The relative age effect observed for speech therapy was of the same magnitude as that observed for methylphenidate in attention-deficit/hyperactivity disorder (positive control outcome). No relative age effect was observed for the initiation of desmopressin for nocturnal enuresis (negative control outcome). This cohort study found that among children in the same grade, an age difference of a few months was associated with the frequency of initiation of speech therapy. These findings may be attributable to a mismatch between the expectations of the school system and the relative age and level of maturity of the children or earlier identification of neurodevelopmental disorders in the youngest children in each age group.

This article uses pupil’s month of birth as a natural experiment to study how immigrant-native inequalities in retention rates are produced. We argue that, compared to native-born parents, immigrant parents face additional disadvantage when dealing with the age disadvantage of their children. We test this hypothesis using a regression discontinuity design with the French sample of the Programme for International Student Assessment. We find that pupils born before the cut-off date for entering primary school are 9 percentage points more likely to repeat a grade in primary school. In line with the double disadvantage hypothesis, the relative age effect is 10 percentage points higher for children with two immigrant parents, while we do not find a difference for children with one immigrant parent. However, the relative age effect is reduced to 4 percentage points when adjusting for the differential effect of parental resources, suggesting that part of the disadvantage is due to compositional differences in socio-economic background and part is immigrant-specific.

This study examines how the probability of becoming a professional football player depends on the birth month (relative age effect) and birth order. These two factors are random and cannot be controlled by the athlete. If these factors influence the probability of the occurrence of top athletes, they not only create inequality but also close the disciplines to potentially talented athletes, lowering the level of competition. Therefore, in this study, we statistically clarified the presence or absence of “giftedness of life” by focusing on the birth month and birth order of professional football league players in the Japan Professional Football League (J-League). Our results indicate that the probability of the occurrence of J-League players decreases significantly with increasing birth order and birth month (180 days, from April onward). Moreover, we found that second-born players with an older brother had higher estimated salaries than players without siblings. These results reveal the characteristics of excellent football players and suggest the importance and direction of improvement in talent discovery and development in sports. Based on our results, we recommend improvements in the player training system to buffer the effects of relative age effect and birth order.

The youngest children in a school class are more likely than the oldest to be diagnosed with ADHD, but this relative age effect is less frequent in older than in younger school-grade children. However, no study has explored the association between relative age and the persistence of ADHD diagnosis at older ages. We aimed to quantify the association between relative age and persistence of ADHD at older ages. For this meta-analysis, we searched MEDLINE, Embase, CINAHL, PsycINFO, and PubPsych up to April 1, 2022, with terms related to "cohort" and "ADHD" with no date, publication type, or language restrictions. We gathered individual participant data from prospective cohorts that included at least ten children identified with ADHD before age 10 years. ADHD was defined by either a clinical diagnosis or symptoms exceeding clinical cutoffs. Relative age was recorded as the month of birth in relation to the school-entry cutoff date. Study authors were invited to share raw data or to apply a script to analyse data locally and generate anonymised results. Our outcome was ADHD status at a diagnostic reassessment, conducted at least 4 years after the initial assessment and after age 10 years. No information on sex, gender, or ethnicity was collected. We did a two-stage random-effects individual participant data meta-analysis to assess the association of relative age with persistence of ADHD at follow-up. This study was registered with PROSPERO, CRD42020212650. Of 33 119 studies generated by our search, we identified 130 eligible unique studies and were able to gather individual participant data from 57 prospective studies following up 6504 children with ADHD. After exclusion of 16 studies in regions with a flexible school entry system that did not allow confident linkage of birthdate to relative age, the primary analysis included 41 studies in 15 countries following up 4708 children for a period of 4 to 33 years. We found that younger relative age was not statistically significantly associated with ADHD persistence at follow-up (odds ratio 1·02, 95% CI 0·99-1·06; p=0·19). We observed statistically significant heterogeneity in our model (Q=75·82, p=0·0011, I2=45%). Participant-level sensitivity analyses showed similar results in cohorts with a robust relative age effect at baseline and when restricting to cohorts involving children with a clinical diagnosis of ADHD or with a follow-up duration of more than 10 years. The diagnosis of ADHD in younger children in a class is no more likely to be disconfirmed over time than that of older children in the class. One interpretation is that the relative age effect decreases the likelihood of children of older relative age receiving a diagnosis of ADHD, and another is that assigning a diagnostic label of ADHD leads to unexplored carryover effects of the initial diagnosis that persist over time. Future studies should be conducted to explore these interpretations further. None.

BackgroundChildren born later in the year have elevated probability to be diagnosed with attention-deficit/hyperactivity disorder (ADHD). We examine when this relative age effect (RAE) - suggested to indicate overdiagnosis - emerges, and has it changed across cohorts.MethodsWe used register-based data on 355,421 children born in Finland in 2005-2010. Information on ADHD medication purchases and healthcare records from specialized and primary care (ICD10-code F90) were used to identify age- and gender-specific probability of diagnosis. RAE at ages 5 to 10 was estimated by regressing the probability of diagnosis on relative age, measured as the day of birth within a year. RAE is presented as percentage point (pp) change in diagnosis probability by one month increase in relative age.ResultsThe probability of ADHD diagnosis at ages 5 to 6 remained below 0.5% for boys in all cohorts and was even lower for girls. RAE was either non-existent or slightly negative, meaning that children born towards the end of the year were less likely than others to receive diagnosis before school age. ADHD diagnoses started to increase after school entry, and RAE emerged at age 7 among boys and by age 8 among girls in all cohorts. Among boys, the overall probability to receive ADHD diagnosis was highest at age 8, and increased from 0.7% to 1.4% between 2005 and 2010 cohorts, whereas RAE increased from 0.07 pp to 0.10 pp. Among girls, the probability of diagnosis at age 8 increased from 0.2% to 0.4%, whereas RAE remained around 0.02 pp.ConclusionsThe lack of relative age effect in the probability of ADHD diagnosis before school age and its emergence immediately after school entry aligns with the idea that ADHD diagnoses are influenced by grade-specific assessments, with those relatively young subject to overdiagnosis. Relative age effect persists across cohorts, and even increases among boys in younger cohorts.Key messages• Relative age does not predict the probability of ADHD diagnosis before school age, but immediately after school entry the probability of diagnosis increases for those youngest in class.• For the most recent cohorts, relative age effect in ADHD diagnoses following school entry increased among boys and remained persistent among girls.

In most education systems, the age of a given cohort of students spans up to 12 months, which creates a within-class age difference, or relative age effect, that tends to disadvantage younger students. Because birth month indeed correlates with academic performance, with poorer outcomes for students born later in the year, the effect can have lifelong consequences for students, whose academic performance justifies their acceptance into different educational tracks. Although past studies have identified the relative age effect in students' choice of educational track in school systems in which students make such choices at the age of 10-14 years, we examined data from the Norwegian school system, in which education tracks are chosen at the age of 15-16 years. The dataset included the variables birth month, track choice, and gender, of all 28,231 pupils at the upper secondary school level in a school county in Norway. Birth month was compared between vocational and academic track choices and the results revealed a significant relative age effect on educational choices between academic and vocational tracks, such that younger students were significantly more likely to apply for vocational tracks. The effect was significantly stronger for boys compared to girls. This indicates that the choice of educational track may reflect students' relative age, especially among boys, and hence, not be based on interests alone. Those findings have implications for actors involved in ensuring equity in education systems in Norway and elsewhere.

The relative age effect (RAE) has been described as the consequence of differences in ages between individuals within the same age group. In youth sports, relatively older children may have a physical and developmental advantage over younger children. The purpose of this study was to determine the relationship between relative age and sports injury in a cohort of pediatric athletes. A probability sample (n = 1997) of children between 5 and 17 yr of age with sports injuries were extracted from a regional hospital database. Relative age was defined as a child's birth month relative to the month that his/her activity uses as an arbitrary age cutoff. The main outcome measure was an activity-specific birth month ratio, which was developed and compared with birth month data for the state. Linear regression models were used to determine overrepresentation and underrepresentation of sports injuries for prepubescent (5-13 yr) and pubescent (14-17 yr) groups separately. Among prepubescent patients, the linear regression model indicated a significant RAE on sports injury (R = 0.037), where those born in or right after the cutoff month for their sports were underrepresented in the study cohort relative to their representation in the general population. For the pubescent group, the RAE was reversed, where those born closest, but before the age cutoff date for their sports were the least represented relative to the general population (R = 0.096). These results demonstrate an RAE on youth sports injury risk in a cohort of pediatric athletes with sports-related injuries. These findings may be used to inform safe practices within sports participation among youth athletes.

The literature on relative age position effects is rather inconsistent. In this study we examined intra-classroom age position (or relative age) effects on Dutch adolescents’ school progress and performance (as rated by teachers), physical development, temperamental development (fear and frustration), and depressive symptoms, all adjusted for age at the time of measurement. Data were derived from three waves of Tracking Adolescents' Individuals Lives Survey (TRAILS) of 2230 Dutch adolescents (baseline mean age 11.1, SD = 0.6, 51% girls). Albeit relative age predicted school progress (grade retention ORs = 0.83 for each month, skipped grade OR = 1.47, both p<.001), our key observation is the absence of substantial developmental differences as a result of relative age position in Dutch adolescents with a normative school trajectory, in contrast to most literature. For adolescents who had repeated a grade inverse relative age effects were observed, in terms of physical development and school performance, as well as on depressive symptoms, favoring the relatively young. Cross-cultural differences in relative age effect may be partly explained by the decision threshold for grade retention.

Previous studies have found a significant effect of pupil's month of birth on their school- and sports performances. The current study investigates whether this so-called relative age effect also exists in a rather unexplored domain, namely popularity among adolescents in school classes. Whereas prior studies examined relative age related to the cut-off date at primary school entry, we also study possible relative age effects regarding the age composition within pupils' current school class. Data are from nationally-representative surveys among 14-15 year-old pupils from the Netherlands, Sweden and England. Results indicate a statistically significant positive relation of both types of relative age with popularity status in classes. The relation of past relative age is particularly strong in England, which has a system of social promotion, whereas current relative age is strong in the Netherlands, with its system of grade retention. These findings underscore the importance of education policy.

Previous studies have found a significant effect of pupil’s month of birth on their school- and sports performances. The current study investigates whether this so-called relative age effect also exists in a rather unexplored domain, namely popularity among adolescents in school classes. Whereas prior studies examined relative age related to the cut-off date at primary school entry, we also study possible relative age effects regarding the age composition within pupils’ current school class. Data are from nationally-representative surveys among 14–15 year-old pupils from the Netherlands, Sweden and England. Results indicate a statistically significant positive relation of both types of relative age with popularity status in classes. The relation of past relative age is particularly strong in England, which has a system of social promotion, whereas current relative age is strong in the Netherlands, with its system of grade retention. These findings underscore the importance of education policy.

The purpose of this study was to investigate the degree of relative age effect (RAE) among the best Norwegian track and field athletes of all time, aged 13 years to senior, as well as to investigate the differences between athletes in events that impose different demands on their physical characteristics, categorised in endurance and explosiveness. The degree of RAE was investigated by examining the difference between the sample’s (N = 21,711) quarterly birth distribution and the quarterly distribution of birth of the Norwegian population as a whole from 1966 to 2019. To determine whether or not an RAE was present, chi-square tests (χ2) were conducted against an even distribution, with Cramer’s V (phi or ɸ) as a measure of effect size. The study’s results show a strong RAE in the two youngest age groups in both genders. RAE decreases with increasing age, but the effect is still present at the senior level in both men and women. Furthermore, the degree of RAE was strongest in explosive events in both boys (ɸ = 0.46) and girls (ɸ = 0.30), while in endurance events it was strong in boys (ɸ = 0.38) but not in girls (ɸ = 0.13). Prominent effect of RAE in the 13- and 14-year-old classes can be explained by the fact that in the youngest age groups impose the highest relative age difference. In addition, this is an age group where there are large differences in growth spurts, physical characteristics and training experience. Elimination of RAE with increasing age may be due to the fact that after puberty inherent physical advantages as a result of the month of birth are evened out. The prominent RAE in explosive events and in boys may be due to the fact that puberty and growth spurts make boys faster, stronger and larger, while puberty and growth spurts in girls are not always beneficial for girls in track and field events. The practical significance of the results relates to athletes developmental opportunities. Irrespective of whether young track and field athletes are relatively older or younger they should be met with patience and dedication from coaches. Superficial short-term categorization of young athletes potential do more harm than good.

Relative age effect (RAE) refers to the phenomenon by which children born early in their year of birth perform more highly than children born later in the same cohort. The purpose of this study was to evaluate whether an RAE exists in the Norwegian numeracy test for 5th, 8th, and 9th graders (National sample of 175,760). The results showed that the RAE is consistent across 5th, 8th, and 9th graders for both boys and girls. Mean scores decreased systematically with month of birth for both genders, and the mean scores for boys were higher compared with girls. The most interesting result and novelty is the gender difference in RAE observed analyzing high- vs. low scorers. Boys born early in the year were overrepresented as high scorers (RAE advantage), whereas girls born late in the year were overrepresented as low scorers (RAE disadvantage). It would be beneficial for researchers, teachers and education policymakers to be aware of RAE, both in terms of the practical use and implications of test results and to help identify strategies to adjust for relative age differences in national tests.

To determine whether youth in Alberta who had completed suicide were more likely to be younger than their classmates on entering grade 1 (that is, showed a relative age effect). Records were obtained for all deaths by suicide by individuals under the age of 20 years in Alberta during the years 1979-1992. The relative age of each of these persons was determined by comparing his or her month of birth to the birth months of the appropriate school-grade cohort. A disproportionate number of the subjects were born in the second half of the "school eligibility year," indicating a higher probability that those who completed suicide were younger than their classmates. Previous research indicates that relative age is strongly related to school performance and success in sports. The present study demonstrates that the relative age effect is also a factor in youth suicide. It is suggested that the higher incidence of youth suicide in the group of relatively younger school children may have resulted from poorer school performance, which in turn led to lowered confidence and self esteem. Past research suggests that these conditions may predispose children to hopelessness and depression, which are often thought to be essential components of suicide. Research aimed at neutralizing the negative effects of relative age should have important personal and social consequences.

BackgroundFew studies have shown that relatively younger children and adolescents (those born later in the same school year) were less likely to engage in physical activity in a phenomenon termed the relative age effect. Although these studies mainly targeted elementary and middle school students, no study has reported on the relative age effect on physical activity in ordinary high school students. Moreover, the relative age effect on sedentary behavior might show an opposite association with physical activity. Therefore, we aimed to clarify the relative age effects on physical activity and sedentary behavior across different school stages in Japanese children and adolescents.MethodsA cross-sectional questionnaire survey was conducted with 21,491 children and adolescents (elementary, middle, and high school students aged 10–18 years) in various Japanese regions from January 2018 to July 2019. Overall, 18,281 children and adolescents (10,299 boys and 7,982 girls) were finally included in our analysis. Data on the birth month, frequency and duration of their physical activity (vigorous, moderate, and moderate-to-vigorous intensity), and sedentary behavior (weekday and weekend total sedentary time, television viewing, playing video games, and Internet use) were obtained. We utilized two-part model regression analyses. Statistically significant association with birth month indicated that a relative age effect was observed.ResultsThe relatively younger individuals were less likely to engage in physical activity (especially vigorous physical activity (VPA)); this association was observed in middle and high school students. Conversely, the relatively younger boys spent more time during weekends with sedentary behaviors and Internet use. Based on school stage, the relative age effect on VPA time was observed in middle school boys (average margin effect (AME) = -0.74, p < 0.01) and high school students (boys: AME = -0.69, p < 0.01; girls: AME = -0.53, p < 0.05). The relative age effect on sedentary behavior was observed during weekends with sedentary behaviors (AME = 3.55, p < 0.01), playing video games (AME = 0.72, p < 0.05) and Internet use (AME = 2.46, p < 0.01) for male high school students and on television viewing (AME = 1.12, p < 0.05) for female middle school students.ConclusionThe relative age effect on physical activity can persist after middle school, and the relatively younger individuals are more likely to replace physical activity with sedentary behavior.

The relative age effect (RAE) represents an asymmetry in birth quarter distribution, favoring athletes born early in the selection year and discriminating against late born athletes. The RAE was proven to be present in all age categories of national and international levels of alpine ski racing. Due to the existence of the RAE in all categories, it can be assumed that a selection error takes place favoring early born and early maturing youth ski racers. However, whether selection strategies have changed during the last years due to the high amount of research done in this field, has not been investigated so far in this sport. Therefore, the aim of the present study was to assess whether the magnitude of the RAE in youth ski racers aged 10–14 years has changed during the last decade by comparing the periods 2005–2009 (“former” athletes) and 2015–2019 (“current” athletes). Pupils of a well-known skiing-specific secondary modern school as well as members of the provincial ski team, who all competed at national levels, were included in the study. Next to the birth months, anthropometric characteristics (body height, weight, body mass index) were assessed. Chi-square tests were used to compare differences between the observed and expected relative age quarter distributions across five age categories (U11–U15). Additionally, Kruskal–Wallis-H-Tests were performed to assess differences in anthropometric characteristics between athletes of the four relative age quarters. Mann–Whitney U-Tests were performed to assess possible differences in anthropometric characteristics between former and current ski racers. A highly significant RAE was present in both former [χ2(3, 764) = 60.36; p < 0.001; ω = 0.31] and current youth ski racers [χ2(3, 702) = 43.13; p < 0.001; ω = 0.29] with an over-representation of athletes of Q1 (30.3–34.2%) and a clear under-representation of athletes of Q4 (14.8–15.0%). Generally, results indicated no change in the magnitude of the RAE in youth alpine ski racing over the past 10–15 years, emphasizing the robust nature of this phenomenon. No significant differences were found in any of the anthropometric characteristics between athletes of the four relative age quarters in both former and current athletes, indicating that relatively younger athletes of the last relative age quarter seem to have to have advanced anthropometric characteristics for being selected. Changes in the talent selection process should be performed to reduce the impact of the RAE.