This version was machine-translated from German and has not been medically reviewed. The authoritative version is the German version.

INTERGROWTH-21st size at birth of very preterm infants (24+0 to 32+6 weeks)

Birth weight, length and head circumference of very preterm infants according to INTERGROWTH-21st, with z-score and SGA/LGA

About this calculator

Percentiles and z-scores of birth weight, length and head circumference according to the INTERGROWTH-21st Very Preterm Size at Birth Reference (Villar 2016), to the exact day from 24+0 to 32+6 weeks. From 33+0 weeks the Newborn Size Standard applies.

Postmenstrual age = gestational age at birth + age since birth. For classification at birth (SGA/AGA/LGA), completed weeks are customary; here the curves are interpolated to the day.

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Reference and license

INTERGROWTH-21st very preterm infants – 24+0 to 32+6 weeks (gestational age at birth).
Villar J, Giuliani F, Fenton TR, Ohuma EO, Ismail LC, Kennedy SH et al. INTERGROWTH-21st very preterm size at birth reference charts. Lancet. 2016;387(10021):844–845. License: terms of use of the INTERGROWTH-21st data not clarified (portal intergrowth21.com public and free of charge; whether use in a calculator is permitted is not documented). Coefficients from the R package gigs (LSHTM, github.com/lshtm-gigs/gigs); its GPL ≥ 3 license applies to the R code, not to the data. Only the calculation has been reproduced here, no code adopted. Source
Reference (observed births), not a standard: children born this early are rarely born healthy. Applies only to birth measurements. Formulas as in the R package gigs; after rounding they match the published INTERGROWTH tables exactly.

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Note

Calculation aid for healthcare professionals. Percentiles and z-scores describe the position of a measured value in the reference population; clinical assessment remains with the treating physician.

Review date of the German original: 2026-11-08 · Methodology

Frequently asked questions

INTERGROWTH-21st size at birth of very preterm infants (24+0 to 32+6 weeks): What does this calculator compute?

INTERGROWTH-21st size at birth of very preterm infants (24+0 to 32+6 weeks): What sources is this calculator based on?

Villar J, Giuliani F, Fenton TR, Ohuma EO, Ismail LC, Kennedy SH et al. INTERGROWTH-21st very preterm size at birth reference charts. Lancet. 2016;387(10021):844–845.