Weight standards for organs from early human fetuses

One hundred and thirty‐six unfixed fetuses below 500 gm of body weight were examined and the brain, liver, lung, kidney, heart, adrenal, thymus, spleen, and thyroid were weighed. The ratios of organ weight to body weight could be divided into four general patterns: (1) constant; liver, heart, brain, and thyroid (2) increasing; thymus, adrenal, and spleen (3) initially increasing and then reaching a plateau; kidney, and (4) increasing and then decreasing; lung. Graphs of the mean and 95% confidence levels along with the formulas used for derivation are given for each organ on the basis of body weight.