INTERGROWTH-21st newborn size at birth calculator (24 to 42 completed weeks)

Newborn infants, 24 to 42 completed weeks at birth: weight, length, head circumference and weight-to-length ratio at birth.

International standards for size at birth from 33 completed weeks (Villar 2014), and INTERGROWTH-21st's very preterm size at birth references below 33 weeks (Villar 2016).

Z-scores and centiles come from the INTERGROWTH-21st models: a normal distribution below 33 weeks and for the weight-to-length ratio, a skew t distribution from 33 completed weeks.