 Description

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.

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)))