Effect of lactation suppressants on the coagulation mechanism.

The effect on the coagulation mechanism of lactation suppressants was determined by comparing observations on a group of untreated women and two other groups, one receiving Vallestril (methallenestrill 20 mg) and the other Ortho-Novum 5 (5 mg norethindrone and 0.075 mg mestranol). Blood was drawn on the first, fourth and tenth days post partum. Patients given Ortho-Novum 5 showed a continued significant elevation of levels of factors VIII and IX for the duration of the study, and the partial thromboplastin time reflected this increase on days 4 and 10. Vallestril appeared to have the same effect on factors VIII and IX, although to a lesser, nonsignificant degree. In addition, the day 10 levels of fibrinogen and factors VII and X, as well as platelet adhesiveness, of the untreated group were lower than those of the groups undergoing treatment, although the medication had been discontinued five days previously. However, this difference was not statistically significant.In view of the growing evidence of the increased incidence of thromboembolic disease during the puerperium, it is perhaps unwise to give drugs that cause changes in the plasma coagulation system, such as those we have described, to patients who are already in a hypercoagulable state.