This blog post was contributed by Cecília Aguiar (ISCTE-IUL).

Every year, in some countries, a number of parents of children who were born in the last months of the year, need to make an important decision: to register in primary school or spend another year in preschool. Meanwhile, teachers reflect on the best recommendation to give to each family. They know how important their opinion is and how much it influences parents’ decisions.

Naturally, parents and preschool teachers, who know each child so well, carefully consider the advantages and disadvantages of each option. They may consider, for example, whether that special friend is also going to primary school; whether the child will get to stay with a teacher that the family already knows; whether the child has the necessary skills to keep up with his/her older peers; whether the child is interested in more structured tasks; etc. 

But…  what does research say about this?

Many studies show that the younger children in each class (this is, often children who were born in the last months of the year) tend to be at a disadvantage in relation to their older [1]. This disadvantage manifests itself in many ways, namely in:

  • Higher probability of lower academic results [2].
  • Higher probability of needing special education services [1, 2].
  • Higher probability of receiving a diagnosis of ADHD or psychological support [1, 3].
  • Lower probability of representing their school in sport competitions [1].

The results of some studies suggest that these effects are long lasting and persist throughout schooling [1, 4]. However, researchers talk about this effect as a relative age effect. And why? Because there is also evidence that, when younger children are assessed at exactly the same age as their peers were previously assessed, they actually perform better [4].

What can explain this relative disadvantage?

There are several explanations for the relative age effect:

  • Older children have a developmental advantage, that is, they have had more time to learn and practice skills [1].
  • Being older and taller is associated with greater social prestige, with positive consequences for social relationships with peers [5].
  • The expectations of peers and teachers may be higher for older children, resulting in a Pygmalion effect, through which peers and teachers behave differently toward younger children and, therefore, negatively influencing their behavior and performance [1, 5].
  • From a motivational point of view, a child who feels competent will be more likely to continue investing time and effort in school activities [1] and to develop positive self-esteem [5].

These (dis)advantages, occurring in isolation or cumulatively, can be decisive for educational success. However, we know that relative age effects sometimes are not observed and that they may vary, depending on the country / educational system [5]. Further, they seem to be more salient in excessively competitive contexts [6] and in children with disabilities or living in poverty [7]. Importantly, critical views of the option to start school later, that typically focus on academic outcomes, should be also carefully considered [8].

What to do, then, in the case of children that are born at the end of the school year? Stay in preschool or register in primary school?

Each child is unique, and parents and teachers must continue to consider a number of factors in their decision-making process. There is evidence suggesting that there are advantages in being one of the oldest children in class in the first years of schooling. Therefore, when in doubt, it could be advantageous for the child to remain in preschool… playing and learning…

Most important of all, however, is that children attend (preschool or elementary) classrooms where age is considered when evaluating progress and that challenge all children in their zone of proximal development. Therefore, ultimately, what matters is that the child benefits from a pedagogical approach that is child-friendly, inclusive, and based on high expectations for all children.

What criteria do you consider to advise parents in these cases? Share your experiences …



[1] Aune, T. K., Ingvaldsen, R. P., Vestheim, O. P., Bjerkeset, O., & Dalen, T. (2018). Relative age effects and gender differences in the national test of numeracy: a population study of norwegian children. Frontiers in Psychology9, 1091. doi:10.3389/fpsyg.2018.01091

[2] Cobley, S., McKenna, J., Baker, J., & Wattie, N. (2009). How pervasive are relative age effects in secondary school education? Journal of Educational Psychology, 101(2), 520–528. doi:10.1037/a0013845

[3] Holland, J., & Sayal, K. (2019). Relative age and ADHD symptoms, diagnosis and medication: A systematic review. European Child & Adolescent Psychiatry28(11), 1417–1429. doi:10.1007/s00787-018-1229-6

[4] Peña, P. A. (2017). Creating winners and losers: Date of birth, relative age in school, and outcomes in childhood and adulthood. Economics of Education Review56, 152-176. doi:10.1016/j.econedurev.2016.12.001

[5] Jeronimus, B. F., Stavrakakis, N., Veenstra, R., & Oldehinkel, A. J. (2015). Relative age effects in Dutch adolescents: Concurrent and prospective analyses. PLoS One10(6), e0128856. doi:10.1371/journal.pone.0128856

[6] Musch, J., & Grondin, S. (2001). Unequal competition as an impediment to personal development: A review of the relative age effect in sport. Developmental Review, 21, 147–167. doi: 10.1006/drev.2000.0516

[7] Datar, A. (2006). Does delaying kindergarten entrance give children a head start? Economics of Education Review25(1), 43-62. doi:10.1016/j.econedurev.2004.10.004

[8] Shanahan, T. (2019). Red shirting kindergarten Kids: Good idea or bad? Blogs About Reading: Shanahan on Literacy. Retrieved from

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When children are born at end of the year: Stay in preschool or register in primary school?
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