Abdominal circumference correlates well with fetal weight. Biparietal diameter correlates with head size, which is a determinant of fetal weight.
Limitations: Abdominal circumference can be difficult to measure accurately by ultrasound. Biparietal diameter can be affected by variation in cranial shape.
Hadlock (1984)
estimated fetal weight in grams =
=10^(1.1134 + (0.1694 * (biparietal diameter in cm)) + (0.007365 * ((biparietal diameter in cm)^2)) + (0.05845 * (abdominal circumference in cm)) - (0.000604 * ((abdominal circumference in cm)^2)) + (0.000595 * (abdominal circumference in cm) * (biparietal diameter in cm)))
The equation was not implemented as unable to obtain valid answers as written.
Shepard (1982)
estimated fetal weight in kilograms =
=10 ^ ( - 1.7492 + (0.166 * (biparietal diameter in cm)) + (0.046 * (abdominal circumference in cm)) - (0.002646 * (abdominal circumference in cm) * (biparietal diameter in cm)))
Thurnau (1983)
estimated fetal weight in grams =
= (9.337 * (abdominal circumference in cm) * (biparietal diameter in cm)) - 299.076
Vintzileos (1987)
estimated fetal weight in grams =
=10^(1.879 + (0.084 * (biparietal diameter in cm)) + (0.026 * (abdominal circumference in cm)))
Warsof (1977)
estimated fetal weight in kilograms =
=10^( - 1.599 + (0.144 * (biparietal diameter in cm)) + (0.032 * (abdominal circumference in cm)) - (0.000111 * (abdominal circumference in cm) * ((biparietal diameter in cm)^2)))
Weinberger (1984)
estimated fetal weight in grams =
= - 481 + (10.1 * (abdominal circumference in cm) * (biparietal diameter in cm))
where:
• equation is intended for fetal weights less than 2000 g
Woo (1985)
estimated fetal weight in grams =
=10^(1.63 + (0.16 * (biparietal diameter in cm)) + (0.00111 * ((abdominal circumference in cm)^2)) - (0.0000859 * (biparietal diameter in cm) * ((abdominal circumference in cm)^2)))
Woo (1986)
estimated fetal weight in grams =
=10^(1.2758 + (0.181864 * (biparietal diameter in cm) + (0.0517505 * (abdominal circumference in cm)) - (0.00334825 * (biparietal diameter in cm) * (abdominal circumference in cm)))
Specialty: Obstetrics & Gynecology, Pedatrics