. 2019 Feb 5;2:49. Originally published 2018 Oct 4. [Version 2] doi: 10.12688/gatesopenres.12869.2

Table 2. Sampling fractions for recruitment in the INTERBIO-21 ^st Newborn Case-Control Study.

GA, or BW for GA centile (C)	To be recruited, %	Case/Control
GA <36 ⁺⁰ weeks (up to and including 35 ⁺⁶)	100%	Preterm case
GA 36 ⁺⁰ to 36 ⁺⁶ weeks	50% ➔ 100% *	Preterm case
GA 37 ⁺⁰ to 37 ⁺⁶ weeks	5% ➔ 20% *	Preterm case
BW/GA <C3 ^rd ➔ <C5 ^th #	100%	SGA case
BW/GA C3 ^rd - C9.9 ^th ➔ C5 ^th – C9.9 ^th #	50%	SGA case
GA 38 ⁺⁰ to 41 ⁺⁶ weeks and BW/GA ≥ C10 ^th	Will vary according to the number of cases recruited	Potential controls to be sampled immediately after each case

GA, gestational age; BW, birth weight. *Change occurred in November 2012. ^#Change occurred in November 2013.

Table 2. Sampling fractions for recruitment in the INTERBIO-21 st Newborn Case-Control Study.