In view of the risk of thrombo-embolism from the postpartum use of oestrogens, an attempt was made to find a non-hormonal substance for the inhibition of lactation. A trial of chlormezanone (Fenarol) showed that it was not better than a placebo and that stilboestrol was distinctly superior in the initial suppression of lactation.

A trial was undertaken with 2 single-dose drugs for the inhibition of postpartum lactation. Two hundred patients were studied, of whom one half were given a single oral tablet of quinestrol (Estrovis) 4 mg. and the other half were given a single intramuscular injection of Ablacton. The results showed that both preparations were equally effective in the initial inhibition of lactation and were rarely associated with rebound breast engorgement or withdrawal bleeding.