The INTERGROWTH-21st global references and z scores for head circumference, length and weight at birth of very preterm newborns are available to download below.
A Windows application and an online browser based tool that enables birth weight, length and head circumference to be classified according to these international references has also been developed and is accessible here.
(These follow from the most recent INTERGROWTH-21st publication in The Lancet which can be accessed here.)
Reference: Villar J, Giuliani F, Fenton TR, Ohuma EO, Cheikh Ismail L, Kennedy SH, for the INTERGROWTH-21st Consortium. INTERGROWTH-21st very preterm size at birth reference charts. Lancet 2016 doi.org/10.1016/S0140-6736(16) 00384-6.