Figure 3.

Mean measured FEV₁ as fraction of expected peak FEV₁ (with 95% CIs) in three population based cohorts born extremely preterm (born at gestational age ≤28 weeks or birth weight ≤1000 g) during three different decades (blue, green and yellow lines), and aggregated data for their individually matched term-born controls (black line), based on mixed-effects longitudinal model. Expected peak FEV₁ was calculated for each individual using the GLI reference equation. FEV₁: forced expiratory volume in 1 s; GLI, global lung function initiative.