Abstract
Immunoreactivity that is contents/affinity of natural antibodies (N-Ab) of IgG class to developmentally related proteins MBP, S100, ACBP14/18 and MP65 were measured in serum samples of 1987 women at their pregnancy terms of 3–12 weeks. The pregnancy results of the examined women were analyzed 4–9 months later. It was revealed that frequencies of cases of stopped early pregnancies, intrauterine and antenatal fetal deaths, and births of newborns with coarse inborn defects are directly related to deviation of the examined maternal N-Ab content/affinity from the physiological limits: abnormally high as well as abnormally low reactivity during first trimester of pregnancy, both could be related to unfavorable results of pregnancy.