Figure 1.

Daily volume of blood sampled (mL/kg) in a cohort of 149 extremely preterm infants. During postnatal days 1‐14, median (IQR) blood sampling volume was 40.4 (23.9‐53.3) mL/kg, which corresponded to 58% of the total endogenous blood volume. The majority of blood samples were drawn during the first week of life and corresponded to a median (IQR) of 24.3 (16.7‐33.8) mL/kg, equivalent to 35% of the total endogenous blood volume. Boxes illustrating 25th percentile (bottom), median and 75th percentile (top), whiskers illustrate 1.5 times the IQR, or if no case has a value in that range, minimum and maximum. Outliers illustrated by a small circle and extreme outliers, defined as three times the IQR, illustrated by an asterisk. IQR, interquartile range