Maternal blood group in ABO and Rh systems and somatic conditions of newborns. A group of 5454 eutrophic newborns (2649 female and 2805 male) from Białystok were examined with respect to the following anthropometric features: body mass, crown-rump length (Si), head and chest circumferences and their, relation to the maternal ABO and Rh blood groups. The mathematical description was done with the aid of computer (Statistica 4.0 for Windows) estimating statistical characteristics specific for mass phenomenon of regular distribution (x, SD). Significance of the obtained differences was evaluated with student t test. On the basis of the carried out research, it can be concluded that maternal blood group A may favor male newborns to have higher mean values of body mass, head and chest circumferences, and female newborns--of head circumference only. The crown-rump length of newborns of both sexes does not show any alterations in relation to maternal blood group. Maternal Rh has no influence on the examined somatic development parameters of the newborns either.