[The frequency of premature labor before and after administering beta-sympathomimetics in clinical practice].

From 1971 to 1975, when beta sympathicomimetics were not used, from total 13 561 deliveries 6.06% were preterm deliveries. In years 1976-1980, when these tocolytics are routinely used from total 15 242 deliveries 5.24% were preterm deliveries. Significance is statistically characteristic, p = = 0,01. In the anamnesis of all parturients in both periods, frequency of factors which effect on the rate of preterm deliveries is equal.