Gender-specific weight estimation of fetuses between 2,501 and 3,999 g--new regression formulae.

OBJECTIVE To develop new gender-specific regression formulae to estimate fetal weight focusing on a particular weight range from 2,501 to 3,999 g. METHODS 3,254 singleton pregnancies were included to generate new regression formulae for female and male fetuses, and to evaluate their accuracy. RESULTS In comparison with commonly used formulae, the new gender-specific and weight-range-specific method of fetal weight estimation provided greater accuracy. The mean absolute error was less than 7%. CONCLUSIONS When properly used, the new formulae can improve the accuracy of weight estimations in fetuses between 2,501 and 3,999 g.