[A study of blood coagulation and fibrinolysis in a small-for- gestational-age infant birth group].

In order to approach from the aspect of blood coagulation and fibrinolysis the reason for the birth of SGA (small for gestational age) infants, we studied the blood coagulation and fibrinolysis capacity of maternal venous blood in the 36th and 37th weeks after conception employing 54 cases in which were no abnormality was seen during pregnancy up to delivery, and we also studied the relationship of the body weight at delivery and arrived at the following conclusions. In the SGA infant birth group there was a tendency toward acceleration of blood coagulation, acceleration of blood platelet aggregation and inhibition of fibrinolysis when compared with two other groups i.e. AGA (appropriate for gestational age) and LGA (large for gestational age) infant birth groups. In the SGA infant birth group in particular there was seen a statistically significant reduction in prothrombin time (p less than 0.002) when compared with the other two groups. A correlation was noted between prothrombin time for maternal blood and the infant's body weight at birth (r = 0.38446, p less than 0.01), and the shorter the prothrombin time for maternal blood in the late stage of pregnancy, the lower the infant's body weight tended to be at birth. The results indicate that these changes in blood coagulation and fibrinolysis may influence the decrease in the blood output of the uterine placenta, and it may be assumed that this causes the birth of SGA infants. Furthermore, the prothrombin time values become one of the parameters used in forecasting an SGA infant's birth, and this should to be considered as a new fibrinolytic therapy for SGA infants.