[From Sex, Society and Medieval Women by N. M. Heckel]
The Middle English Trotula on Abortion:
Also þe rote of yres vnder put into þe marice oþer subfumygid with yres makith her to lessen her chylde, for yres rotes ben hote & drye & haue vertu to opyne & to hete & to consume & waste. For whan the woman is feble & þe chyld may no3t comyn out, than it is better that þe chylde be slayne than the moder of þe child also dye. And also it bringeth forth þe ded chylde mervelously & þe secundine & menstrua with hit.
[Also, the root of iris put into the womb or fumigated underneath makes a woman lose her child, for iris roots are hot and dry and have the virtue of opening, heating, consuming, and wasting. For when the woman is feeble and the child cannot come out, then it is better that the child be killed than the mother of the child also die. And also the medicament brings out the dead child marvellously, and the secundine, and menstrual fluid.] (Rowland, 96-97.)
Medieval Woman's Guide to Health: The First English Gynecological Handbook. Ed. and trans. Beryl Rowland. Kent, OH: The Kent State University Press, 1981.