MATHEMATICAL REPRESENTATION OF ORGAN GROWTH IN THE HUMAN EMBRYO FETUS

During human pregnancy, there is a huge increase in the total weight o f the embryo/fetus from conception to term. The total growth, which is the summation of growth of the various organs and tissues that make u p the organism, was analyzed in a previous paper and fitted to the Gom pertz equation for growth. In the present study, allometry, the quanti tative representation of the consequence of size; was utilized to desc ribe the correlation of individual fetal organ/tissue weights with the total fetal weight. The organ/tissue weight and the total fetal weigh t data used in the analyses were pooled from various sources that prov ided data ranging from 25 days to 300 days post-conception. Allometric equations are presented for 16 embryo/fetal organs and tissues. The s tandard allometric equation gave adequate fits for embryo/fetal adrena l, bone, bone marrow, brain, heart, liver, pancreas, plasma, skeletal muscle, extracellular water, thymus and thyroid; but it was necessary to use a quadratic form of the allometric equation for embryo/fetal fa t, kidney, lung and spleen. Parameters were also calculated for crown- to-rump and crown-to-heels for fetal lengths that occur during pregnan cy.