Sensitivity of a double-blind trial of ritodrine and placebo in twin pregnancy.

A critical examination is made of the results of a recently reported double blind trial comparing ritodrine and placebo. It is shown that interval estimates are more informative than p-values obtained from significance tests and that the trial involving 49 patients was insensitive to differences which could be clinically important. Contrary to the conclusions presented, the data suggest that further evaluation of the effects of ritodrine in twin pregnancies is necessary to clarify the situation.