Of 266 patients admitted with threatened abortion, 135 (50.8%) aborted, while 131 (49.2%) gave birth to 106 full term children and 25 premature children. Three of these children suffered from malformations. The risk of abortion was greater the earlier in pregnancy the symptoms occurred, and the longer and more severe the haemorrhage. In addition the frequency of abortion increased with increasing maternal age, with an increasing number of pregnancies, and if the patient had had a previous legal abortion, whereas earlier spontaneous abortion did not affect the prognosis. The frequency of abortion also rose in the lower social groups, and it was particularly high among the unmarried women. The risk of a premature child was 3 times greater after a threatened abortion than after a normal pregnancy. The perinatal mortality was not increased in full term children, but among the premature children it was found to be very high, in fact many times higher than among premature children as a whole.