Associations between EFW and kindergarten-age child development
For both the INTERGROWTH and WHO charts, estimated fetal weight percentile was positively associated with EDI scores, with lower median test scores and higher risks of developmental vulnerability among smaller infants (Figure 1 ). However, the magnitude of the differences between smaller fetuses and those between the 31st to 90th percentile was generally modest (Tables 2 and 3 ). For example, children with an estimated fetal weight between the 31st to 90th centile of the INTERGROWTH chart had a mean EDI score of 40.6, while infants between the 3rd to 9th centile had a mean score of 37.8; a mean difference between the scores of only -2.8 [95% CI: -5.1, -0.5]. The most pronounced difference was observed among children who were <3rd percentile of the WHO chart, whose EDI scores were -4.7 [95% CI: -7.1,-2.3] lower than those with an EFW between the 31st and 90thpercentile.
The risks of developmental vulnerability were lowest among children with an EFW between the 31st and 90thpercentile (30.1% risk using the INTERGROWTH chart, 29.2% risk using the WHO chart). Risks were increased in lower EFW categories (e.g., 35-40% in categories <20th percentile of the INTERGROWTH chart, and 35-45% in categories<20th percentile of the WHO chart, Tables 2 and 3 ). Risk ratios for these differences were significantly different than the null for some, but not all of these lower percentile categories. Similar trends were observed for the two EDI subscales (Figure S1 ), and special needs designation (Figure S2 ), although small numbers for this latter outcome precluded firm conclusions.