BRITISH MEDICAL JOURNAL 6 JANUARY 1973 21 lytic activity. Such changes have been interpreted as a physiological development to provide for effective haemostasis and preservation of the maternal blood volume during parturition (Bonnar et al., 1971). The increased levels of coagulation factors associated with pregnancy have been reported as occurring, in the main, in the third trimester. In the present study factors VII and X were found to be increased early in the second trimester. An increase of similar magnitude in the activity of these factors at an unspecified time during the second trimester was reported by Nilsson and Kullander (1967). Already there are reports emphasizing the haemhorragic complications of therapeutic abortion, and it is likely that in some instances defective blood coagulation may be responsible.The increase in the activity of factors V, VIII, and X which were found during induction of abortion in mid-trimester pregnancy by extra-amniotic prostaglandin F2,a indicates that activation of the coagulation system is taking place. In particular the increase of factor X may be due to the escape of thromboplastin substances from the placental site during uterine contractions and especially at the time of placental separation. It has been shown in hamsters that thromboplastin material enters both the maternal and fetal circulation during placenta separation (Brown and Stalker, 1969). During placental separation at term in normal pregnancies increased levels of coagulation factors V and VIII have been found in both peripheral and uterine blood (Bonnar et al., 1970). Stander et al. (1971) suggested that induction of abortion by intra-amniotic injection of hypertonic saline initiates disseminated intravascular coagulation. They reported more extensive changes than were found in the present study.It is of interest that virtually no changes in the coagulation system were found during termination of early pregnancy by vacuum aspiration. It seems, therefore, that when pregnancy is terminated in the mid-trimester, whether by hypertonic saline instillation or by extra-amniotic prostaglandin, coagulation system changes in the circulating blood take place. These are most probably related to the physiological changes which have taken place in the haemostatic system in the second trimester. Coagulation changes associated with abortion will establish a vulnerable state for intravascular clotting and thromboembolic complications. It is likely, therefore, that in susceptible patients termination of pregnancy after the first trimester may give rise to such complications as defective haemostasis or thromboembolic complications.

An open letter to the BMA and the Academy of Medical Royal Colleges calls on them to make a joint public statement of opposition to the amended section 75 regulations