Early-term delivery
Cognitive Scores
The children born at 37 weeks GA had lower mean cognitive scores than
those born at 40 weeks (27 912 children; SMD, -0.13; 95% CI, -0.21 –
-0.05; I2, 54%; moderate certainty evidence; Trim and
Fill, -0.09, -0.18 – -0.01), as shown in Figure 2 a). There was no
significant difference between children born at 38 and 40 weeks GA (33
004 children; SMD, -0.04; 95% CI, -0.08 – 0.002; I2,
42%; moderate certainty evidence; Trim and Fill, -0.04, -0.09 – 0.02)
(Figure 2 a). The children born at early-term (37 and 38 weeks GA
combined) had lower mean cognitive scores than full-term (39 to 41
weeks) born children (39 171 children, SMD, -0.14; 95% CI, -0.26 –
-0.02; I2, 95%; low certainty evidence; no
publication bias) (Figure 2 a). Due to the high heterogeneity, we
conducted a subgroup analysis based on the age of follow-up. The mean
differences tended to be smaller in older children (see Appendix S5).
Cognitive impairment
More cognitive impairment cases were found in children born at 37 weeks
(71 597 children; OR, 1.23; 95% CI, 1.13 – 1.33; I2,
49%; moderate certainty evidence; Trim and Fill, 1.30, 1.20 – 1.42)
and at 38 weeks (92 572 children; OR, 1.08; 95% CI, 1.03 – 1.12;
I2, 0%; moderate certainty evidence; no publication
bias) compared to those born at 40 weeks (Figure 2 b). Cognitive
impairment was more common in early-term born children than full-term
(939 397 children; OR, 1.19; 95% CI, 1.13 – 1.25;
I2, 86%; low certainty evidence; Trim and Fill, 1.17,
1.11 – 1.23) (Figure 2 b). We also conducted a subgroup analysis based
on age at follow-up in this synthesis, see Appendix S5. The results
showed that the OR for cognitive impairment reduced with increasing age
at follow-up, except for one study55.
Low academic performance
More low academic performance happened in those born at 37 weeks GA (576
869 children; OR, 1.17; 95% CI, 1.02 – 1.35; I2,
96%; moderate certainty evidence; Trim and Fill, 1.03, 0.91 – 1.17)
and 38 weeks GA (614 005 children; OR, 1.10; 95% CI, 1.01 – 1.19;
I2, 92%; moderate certainty evidence; Trim and Fill,
1.03, 0.95 – 1.13) compared to those born at 40 weeks (Figure 2 c). Low
academic performance was more common in early-term born than full-term
children (2 714 784 children; OR, 1.15; 95% CI, 1.09 – 1.21;
I2, 96%; low certainty evidence; Trim and Fill, 1.05,
0.99 – 1.11) (Figure 2 c). The heterogeneity of the studies in these
three data syntheses was high. We conducted subgroup analyses according
to the outcome measurement scales, see Appendix S5.