Nifedipine Treatment in Preterm Labor

• Prolongation of the pregnancy in women with Threatened Preterm Labor [ Time Frame: more than 48 hours/7 days ] [ Designated as safety issue: No ]
  It will be evaluated as a delay in the labor: hours after starting the treatment: more than 48 hours/more than 7 days of prolongation.
• Obstetric results [ Time Frame: at labor and 24 hours after delivery ] [ Designated as safety issue: No ]
  Number of days and type of labor.
• Presence of the neonatal intracranial hemorrhage [ Time Frame: First assessment: in the first week. ] [ Designated as safety issue: Yes ]
  Determination of the appearance and periventricular hemorrhage degree (I-IV) by transfontelar ultrasound scans.
• Presence of neonatal necrotizing enterocolitis [ Time Frame: at birth and at 30 days after labor ] [ Designated as safety issue: Yes ]
  Monitor the need of canalizing the umbilical vein or artery, the days of parenteral nutrition, days to the start of enteral nutrition, type of enteral nutrition (from the mother, artificial or mixed), start of the elimination of meconium, clinical data from the neonatal necrotizing enterocolitis(abdominal strain, vomiting, blood in the feces, septic appearance) and radiologic/ecographic (dilated bowel loops, intestinal pneumatosis, air in portal, pneumoperitoneum).
• Presence of Retinopathy of prematurity (ROP) [ Time Frame: Between the 4th and 6th week of baby life. ] [ Designated as safety issue: Yes ]
  Monitor the iGF1 (Insulin-like growth factor 1) levels on the 3rd week of life as well as an assessing the development of retinopathy.
• Presence of ductus [ Time Frame: At birth and 30 days after labor ] [ Designated as safety issue: Yes ]
  Clinical assessment (heart murmur, jumpy pulse, worsening of the clinical basal situation), echocardiography (confirmation of the ductus, Al/Ao relation, ductal size), medical or surgical treatment necessity.
• Mother Tolerance Results [ Time Frame: at labor and 24 hours after delivery ] [ Designated as safety issue: No ]
  Survey to assess the tolerance to the symptomatology induced by the medicines (flush, tachycardia, digestive upsets).

This is a study for pregnant women who have been diagnosed with Threatened Preterm Labor. The principal aim of this study is to compare the efficacy and safety of Nifedipine treatment versus Atosiban treatment over these patients' newborn babies.

Preterm labor is defined as the presence of uterine contractions of sufficient frequency and intensity to effect progressive effacement and dilation of the cervix prior to term gestation (between 20 and 37 weeks).

It is a major health problem of increased incidence, affecting approximately between 7-10% of pregnant women in developed countries with a high socioeconomic costs and high rates of fetal mortality, although perinatal progress.

This study may allow to establish the existence of differences in perinatal outcomes and to define the first choice drug for tocolysis.

• Drug: Nifedipine

  • Oral Treatment with Nifedipine capsules (10mg)

    • Initial dose: 20 mg of nifedipine (2 capsules of 10 mg).
    • Maintenance Dose: 20 mg of nifedipine (2 capsules of 10 mg) every 6 hours.
  • Maximum Duration of the treatment: 48 hours.
• Drug: Atosiban

  • Intravenously Treatment with Atosiban (7.5mg/ml)

    • Initial Dose: IV bolus injection during 1 minute + Intravenous infusion 7.5 mg/ml during 3 hours.
    • Maintenance: Maintenance intravenous infusion 7.5 mg/ml at least 18 hours to a maximum of 45 hours.
  • Maximum Duration of the treatment: 48 hours.

• Experimental: Nifedipine

  • Oral Treatment with Nifedipine capsules (10 mg)

    • Initial dose: 20 mg of nifedipine (2 capsules of 10 mg).
    • Maintenance Dose: 20 mg of nifedipine (2 capsules of 10 mg) every 6 hours.
  • Maximum Duration of the treatment: 48 hours.
  Intervention: Drug: Nifedipine
• Active Comparator: Atosiban

  • Intravenously Treatment with Atosiban (7.5mg/ml)

    • Initial Dose: IV bolus injection during 1 minute + Intravenous infusion 7.5 mg/ml during 3 hours.
    • Maintenance: Maintenance intravenous infusion 7.5 mg/ml at least 18 hours to a maximum of 45 hours.
  • Maximum Duration of the treatment: 48 hours.
  Intervention: Drug: Atosiban

Inclusion Criteria:

The study population and the inclusion criteria is established by patients between the 24th and 33+6th weeks of pregnancy, fixed by an ecography during the first three-month period, and with a threat of preterm labor (TLP), by the American College of Obstetricians and Gynecologists (ACOG's) criteria:

• Four contractions or more with a duration of at least 30 seconds during 30 minutes

• Documented cervix changes:

  • The cervix changes in a nulliparous woman are: both cervix tact with 0 to 4 cm of dilatation and cervical effacement of at least a 50% (vaginal ultrasound alternative with cervix length two standard curvatures under the average for the gestational age)
  • The cervix changes in a multiparous woman are: 1 to 4 cm of dilatation and cervical effacement of at least a 50% (same ecographic alternative as the nulliparous).
• Patient who had signed the informed consent.

Exclusion Criteria:

Exclusion criteria of the pregnant mother and intrauterine fetal:

• Prior treatment with a different tocolytic from the ones in the protocol.
• Chorioamnionitis.
• Premature rupture of membranes.
• Vaginal Bleeding.
• Major fetal malformations.
• Intrauterine growth retardation (IGR): IGR<percentile 5.
• Cardiopathies (aortic stenosis, congestive heart failure).
• Blood Pressure lower than 100/60 mmHg.
• High transaminase levels.
• Uterine malformations.
• Use of magnesium sulphate.
• Severe hypertensive disorder, defined as blood pressure equal to or greater than 160/100 mmHg or any figure associated with severe preeclampsia.
• Non-reassuring cardiac frequency tracing defined as category II and III of National Institute of Child Health and Human Development (NICHD).
• Asthmatic patients treated with betamimetics.
• Hypertensive patients treated with vasodilators.
• Patient in treatment or treated with another product/s in investigation during the four weeks prior to randomization.
• Hypersensitivity to any drug of the study.