Lineal Growth of Human Fetus 353 



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Simple empirical formulae for expressing the lineal growth of 

 the human fetus. 



By RICHARD E. SCAMMON and L. A. CALKINS. 



[From the Department of Anatomy, University of Minnesota, 

 Minneapolis, Minnesota.] 



In the quantitative study of the growth of the human body 

 there is often need for simple and accurate formulae for express- 

 ing the relation between body-length and prenatal age. Em- 

 pirical formulae for lineal growth in the fetal period (3 lunar 

 months to birth) have been published by Hassee 1 , Henry 

 and Bastien 2 , and Scammorn 3 . No one of these is entirely 

 satisfactory, for the first gives results which are not in 

 accord with modern findings regarding prenatal lineal growth, 

 the second is highly complicated, and the third is primarily for 

 use in estimating the length from the age, whereas one usually 

 desires to determine the age from the length. Practicable 

 formulae of this kind should fulfill the following conditions: (a) 

 They should express age in terms of body-length for the entire 

 fetal period (3 months to birth), (b) They should give a close 

 fit to reliable data on the subject, (c) They should be in simple 

 form, which will permit their application with ordinary arith- 

 metic without the use of tables of special functions and the like. 

 With these conditions in mind the following formulae have been 

 developed on the basis of the data of Mall 4 . 



When Mall's observations are placed in graphic form they ap- 

 proximate a parabola having the general form : T == a + bL 

 + cL 2 , where T is the age in fetal or lunar months (calculated 

 from the first day of the last menstruation), L is the total or 

 crown-heel length in cm., and a, b and c are constants. The 

 specific formula for expressing this relations is : 



1 Hasse, Charite Ann., 1875, ii, 669. 



2 Henry et Bastien, C. R. Acad. Sc., 1904, exxxix, 811. 



3 Seammon, Proc. Soc. Exp. Biol, and Med., 1921, xix, 133. 



4 Mall, Determination of the age of human embryos and fetuses ; Keibel 

 and Mall, Human Embryology, 1910, i, 199. 



