Samples and methods vary in constructing birthweight charts. Introduction of ultrasound dating affects the distribution of gestation, increases the proportion of preterm births, and reduces postterm and small-for-gestational-age (SGA) births. The need for standardized charts is emphasized. Preferably such charts ought to be sex- and parity-specific, also taking into account the mother's previous pregnancy outcome in terms of birthweight. The risks associated with being born SGA involve various morbidity as well as short- and long-term survival.