The purpose of the study was as follows: 1. Assessment of the effectiveness and usefulness of treatment with fenoterol and/or magnesium sulphate depending on the advancement of the preterrn delivery. 2. Assessment of the risk ofpreterrn delivery occurrence in the period up to 7 days depending on the length and opening of the uterine cervix. 3. Clinical assessment of side effects related to the application of fenoterol and/or magnesium sulphate. 4. Assessment of the general status of the premature neonates in women treated with fenoterol and/or magnesium sulphate, based on Apgar scale and Ballard - Klimek scale. Depending on the applied protocol of treatment inhibiting the contracting activity of the uterus , three study groups were formed: Group I (n=233) - pregnant women treated with fenoterol, Group II (n=244) - pregnant women treated with magnesium sulphate, Group III (n=l23)- pregnant women treated with fenoterol and magnesium sulphate. On the basis of the analysis performed, the following conclusions were presented: 1. By comparing the advancement of preterm delivery is was shown that with the length of uterine cervix exceeding 3 cm and opening of uterine cervix not exceeding I cm, the sufficient form of treatment of the preterm contracting activity of the uterus is the treatment with magnesium sulphate. In other cases, fenoterol or fenoterol and magnesiu ; m sulphate are the most effective form of tocolysis. 2. It was shown that in the period up to 7 days from admission, the initial length of uterine cervix equal or exceeding 4 cm decreases the risk of occurrence of a preterm delivery by 80 %. 3. It was stated that initial opening of uterine cervix exceeding 3 cm increases the risk of preterrn delivery by 3.4 in the period up to 7 from admission. 4. When analysing side effects of the tocolytic treatment, it was shown that: • In patients treated only with fenoterol, the most frequent side effect is tachycardia, • In patients treated only with magnesium sulphate, the most frequent symptoms are hot flushes and sleepiness, • Tocolysis on application of fenoterol and magnesium sulphate most frequently results in the occurrence of hot flushes and tachycardia, • Concomitant administration of fenoterol with magnesium sulphate reduces the occurrence of tachycardia in mothers by 11.2 %, • Concomitant administration of fenoterol with magnesium sulphate significantly reduces the value of average basic heart rate of the foetus. 5. Premature neonates of mothers treated with fenoterol and magnesium sulphate had lower average score in the Apgar scale, lower average birth weight, as well as lower maturity according to the Ballard- Klimek's scale as compared to children born prematurely by mothers undergoing other forms of treatm ; ent, which is related to the greatest initial advancement of preterrn delivery in these patients and shorter gestational period.