The project will explore how being born as part of a twin birth or being born premature affects school readiness (performance on entry assessments) and academic outcomes during the early primary school years (Key Stage 1).

There is evidence that twins have poorer academic outcomes during early adulthood relative to singletons (Tsou, Tsou, Wu, & Liu, 2008). It is possible that this is actually a consequence of the increased probability of twins being born preterm or small for gestational age.
In addition, this finding is not consistently observed; a large scale Danish study found no significant differenes in adolescents’ academic outcomes between twins and singletons (Christensen, Petersen, Skytthe, & Hersking, 2006). We aim to explore whether being born as a twin affects school readiness and early academic outcomes relative to being an only child or having one older non-twin sibling and if so, whether this effect persists after controlling for factors known to affect academic outcomes (e.g. birth weight, maternal education).

The second research question aims to examine whether the birth order of twins affects academic outcomes. There is some evidence that first born twins weigh more than second born twins (Yokoyama et al., 2016). Whilst first born twins can be delivered in much the same way as a singleton, there are many more opportunities for obstetric complications (and therefore perinatal compromise) for second born twins, particularly if delivered vaginally. Intrapartum monitoring of the second twin can be challenging, there may be a malpresentation of the second twin requiring internal cephalic version and breech delivery; if these manouveres fail an emergency caesarean section may be required (Leung 2002, Leung 2004). The analysis will therefore explore whether first born twins perform better academically during the primary school years, and whether this effect differs depending on the mode of delivery. Also of interest is whether any effects are reduced or eliminated once controlling for factors such as birth weight and gestational age.

A final analysis will be completed to explore whether children born preterm have worse academic performace relative to their term born siblings. Pettinger et al. (2019) found that gestational age was a significant predictor of whether a child attained a good level of development on the early years foundation stage profile (EYFSP) (e.g. Pettinger et al., 2019). The EYFSP is a mandatory assessment carried out in all state-funded schools at the end of reception year, and is seen as a measure of ‘school readiness’.
However, it is possible that this effect may be (in part) explained by the home environment. Although Pettinger et al. (2019) controlled for factors such as maternal education and receipt of means tested benefits, there may be other unknown environmental factors that affect school readiness. Comparing preterm children to term born siblings would allow us to control for these factors. There is published evidence from Scandinavian studies using sibling matching, which shows that extreme prematurity (<27 weeks gestation) is associated with increased mortality, autism and low educational attainment (D’Onofrio BM, 2013; Risnes KR, 2016). Our work could add significantly more than this, since this study only reported on ‘years in education’ and ‘failing’ education.

These analyses have been completed on the Born in Bradford data already (approval code: SP335). However, the number of children in each analysis is small, limiting the conclusions that can be drawn. We are therefore seeking to replicate our findings using the ALSPAC database, as this would allow us to strengthen our conclusions if the outcomes are replicated. If possible, we also plan to run a set of analyses on a combined dataset, which would allow us to increase the statistical power.