Strengths and limitations
The present systematic review is the best available evidence of cognitive and academic outcomes in early-term born LGA babies as it is the most comprehensive meta-analysis to date exploring the association between early-term birth and cognitive outcomes, and it is also the only systematic review to investigate the association between LGA and cognitive outcomes. The strengths of this review are that we followed a pre-registered protocol to search for articles with no time or language constraints. The population sizes were large and across several countries and follow-up was carried out across childhood.
One limitation of this article is the high heterogeneity of measurements in the definition of cognitive impairment and low academic performance. Included studies that used various metrics for reporting results, and some studies with missing metrics (e.g. SD of the mean) had to be excluded from the meta-analyses. Furthermore, different definitions were utilized for LGA or full-term across studies. For example, although most studies used greater than the 90th percentile as the definition of LGA, several studies used the 80th40 or 85th35, 42 percentile as the definition. Although most studies used the 10-90th percentile as the definition of AGA, some studies used other reference groups, e.g. 20-79th percentile40 or 85-90th percentile43. Even though all fall within the official definition of the 10-90th percentile, the use of different reference groups is likely to alter the effect size of the comparisons. Similarly, N. Libuy (2023)68’s use of births at 39+0-40+6 weeks (rather than 39+0-41+6 weeks) as the full-term reference group also poses a risk of bias in data synthesis. Additionally, only a few studies were stratified according to sex, so the role of sex in their impact could not be discussed in this review.