McDonald's rule
[mik-don´aldz] the length in centimeters of the abdominal contour from the upper margin of the pubic symphysis to the fundus of the uterus, divided by 3.5, gives the duration of pregnancy in lunar months; applicable only after the sixth month of pregnancy.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.