Formulae Based on Biomathematics to Estimate the Standard Value of Fetal Growth of Japanese.

We devised biomathematics-based formulae to estimate the standard values of fetal growth of Japanese after 22 weeks' gestation. The growth rates of bi-parietal diameter (BPD), abdominal circumference (AC), femur length (FL), and estimated fetal body weight (EFBW) at the time of gestation were assumed to be proportional to the product of the value at the time and the rest value of an unknown maximum value, respectively. The EFBW was also assumed to follow a multiple logistic function of BPD, AC and FL to fit the standard values of Japanese fetuses published by the Japan Society of Ultrasonics in Medicine.