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Completed

NCT Number: NCT05343806

Nifedipine Versus Magnesium Sulfate for Late Preterm Tocolysis

Objective: This trial is designed to compare between the effectiveness of nifedipine versus magnesium sulfate (MgSO4) for tocolysis in women with threatened preterm labor.

Patient Population: The population will include pregnant women at gestational age between 32 and 36 weeks who are 18 years old or older and have signs of threatened preterm labor.

Study Design: This is a single-center, prospective, randomized controlled clinical trial. A total of 264 women pregnant between 32 and 36 weeks having threatened preterm labor will be enrolled and randomized into two parallel treatment arms. Patients in the group A will receive nifedipine, while patients in group B will MgSO4 only.

Treatment: All patients will be randomized on the day of enrollment. Patients with threatened preterm labor will receive the respective tocolysis in each group. All patients will receive corticosteroids for lung maturity according to the local protocol.

Primary outcome: Number of women not delivered within 48 hours of starting tocolytic therapy.

Secondary outcomes: perinatal mortality, a composite of adverse neonatal outcomes, birth weight, days on ventilation support, length of admission in neonatal intensive care, prolongation of pregnancy more than 7 days, delivery after 37 weeks of gestation, number of days till delivery, maternal mortality, maternal infection, and harm to mother from intervention.

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Key information

Conditions

Threatened Preterm Labor

Age range

18 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Faculty of Medicine, Assiut University

Asyut, Asyut Governorate, 71515, Egypt

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Pregnant women with threatened preterm labor defined as 3 or more uterine contractions in 30 minutes confirmed by cardiotocography.
  • Gestational age from 32 week + 0 days to (inclusive) 36 weeks + 0 days.
  • Women with singleton or multiple pregnancy.
  • Women with preterm prelabor rupture of membranes (PROM) will be included if they have uterine contractions.

Exclusion criteria

  • Contraindications for the use of either drugs, such as cardiac disease, hypotension, myasthenia gravis, or renal impairment.
  • Contraindications for tocolysis, such as intrauterine demise, intrauterine infection, fetal distress, placental separation, or severe pre-eclampsia.
  • Cervical dilatation > 5 cm.
  • Cervical length > 30 mm by trans-vaginal ultrasound.
  • Cervical cerclage.

Treatment and study plan

Nifedipine 20 Mg

Drug

The initial dose of nifedipine will be 2 × 10 mg nifedipine capsules orally in the first hour, followed by 20 mg slow-release nifedipine every 6 hours for the next 47 hours. In the first hour after starting nifedipine, blood pressure and heart rate will be measured every 15 minutes. If blood pressure remains within the normal limits, treatment will be continued.

Magnesium sulfate

Drug

Women will receive only MgSo4. A loading dose of MgSo4 will be given immediately after enrollment as 4 gm diluted in 200 mL of saline solution administered intravenous over a period of 20 minutes. Afterwards, the maintenance dose of MgSo4 will be administered intravenous in a dose of 1 gm/hour given as 6 gm diluted in 500 mL saline solution titrated with a rate of 100 mL per hour, then this dose is repeated every 6 hours for 48 hours. Respiratory rate and knee jerk will be assessed hourly for women in the MgSo4 group. Serum magnesium level will be measured if clinically indicated.

Primary outcomes

  1. Number of women not delivered within 48 hours of starting tocolytic therapy.

    Time frame: 48 hours

    postponing delivery for at least 48 hours to allow the time for corticosteroid administration for fatal lung maturity

Secondary outcomes

  1. Perinatal mortality

    Time frame: From starting treatment until 1 month of delivery

    Death of the offspring during treatment, labor or neonatal period

  2. A composite of adverse neonatal outcomes

    Time frame: within 1 month of delivery

    convulsions, apnoea, asphyxia, proven meningitis, pneumothorax or sepsis

  3. days on ventilation support

    Time frame: within 1 month of delivery

    number of days on mechanical ventilation

  4. length of admission in neonatal intensive care

    Time frame: within 1 month of delivery

    Number of days in the NICU

  5. Prolongation of pregnancy more than 7 days

    Time frame: 7 days after initiation of therapy

    Number of women not delivering after at least 7 days from starting the intervention

  6. Delivery after 37 weeks of gestation

    Time frame: after 37th week of gestation

    number of women delivered after 37 weeks of gestation

  7. Number of days till delivery

    Time frame: from starting the intervention until delivery

  8. Maternal mortality rate

    Time frame: from starting treatment until 1 month after delivery

    Number of maternal deaths during pregnancy, labor or puerperium

  9. Maternal infection rate

    Time frame: from starting treatment until 1 month after delivery

    Number of women having Chorioamnionitis, Puerperal sepsis, endometritis, or sepsis

  10. Harm to mother from interventions (side effects)

    Time frame: from starting treatment until 1 month after delivery

    admission to intensive care, anaphylactic shock, dyspnoea, hypotension (leading to cardiotocography abnormalities), liver test abnormalities (elevated aspartate aminotransferase (AST) or alanine aminotransferase (ALT)), general side effects (nausea, vomiting, headache) and postpartum haemorrhage defined as >500 mL blood loss

Sponsors and collaborators

Lead sponsor

Assiut University

Other

Registry information

Official study title

Nifedipine Versus Magnesium Sulfate for Tocolysis in Pregnant Women at 32 - 36 Weeks Gestation With Threatened Preterm Labor

Acronym: ASTOS2

Important dates

Study start
2023
Primary completion
2025
Study completion
2025
First posted
Apr 25, 2022
Registry last updated
Apr 22, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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