Skip to content

Nifedipine Versus Magnesium Sulfate for Late Preterm Tocolysis

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

Status
Completed
Phases
Unknown
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT05343806
Acronym
ASTOS2
Enrollment
264
Registered
2022-04-25
Start date
2023-04-13
Completion date
2025-09-01
Last updated
2026-04-22

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Threatened Preterm Labor

Brief summary

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.

Interventions

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.

DRUGMagnesium Sulfate

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.

Sponsors

Assiut University
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
FEMALE
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

1. Pregnant women with threatened preterm labor defined as 3 or more uterine contractions in 30 minutes confirmed by cardiotocography. 2. Gestational age from 32 week + 0 days to (inclusive) 36 weeks + 0 days. 3. Women with singleton or multiple pregnancy. 4. Women with preterm prelabor rupture of membranes (PROM) will be included if they have uterine contractions.

Exclusion criteria

1. Contraindications for the use of either drugs, such as cardiac disease, hypotension, myasthenia gravis, or renal impairment. 2. Contraindications for tocolysis, such as intrauterine demise, intrauterine infection, fetal distress, placental separation, or severe pre-eclampsia. 3. Cervical dilatation \> 5 cm. 4. Cervical length \> 30 mm by trans-vaginal ultrasound. 5. Cervical cerclage.

Design outcomes

Primary

MeasureTime frameDescription
Number of women not delivered within 48 hours of starting tocolytic therapy.48 hourspostponing delivery for at least 48 hours to allow the time for corticosteroid administration for fatal lung maturity

Secondary

MeasureTime frameDescription
Perinatal mortalityFrom starting treatment until 1 month of deliveryDeath of the offspring during treatment, labor or neonatal period
A composite of adverse neonatal outcomeswithin 1 month of deliveryconvulsions, apnoea, asphyxia, proven meningitis, pneumothorax or sepsis
days on ventilation supportwithin 1 month of deliverynumber of days on mechanical ventilation
length of admission in neonatal intensive carewithin 1 month of deliveryNumber of days in the NICU
Prolongation of pregnancy more than 7 days7 days after initiation of therapyNumber of women not delivering after at least 7 days from starting the intervention
Delivery after 37 weeks of gestationafter 37th week of gestationnumber of women delivered after 37 weeks of gestation
Number of days till deliveryfrom starting the intervention until delivery
Maternal mortality ratefrom starting treatment until 1 month after deliveryNumber of maternal deaths during pregnancy, labor or puerperium
Maternal infection ratefrom starting treatment until 1 month after deliveryNumber of women having Chorioamnionitis, Puerperal sepsis, endometritis, or sepsis
Harm to mother from interventions (side effects)from starting treatment until 1 month after deliveryadmission 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

Countries

Egypt

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Apr 23, 2026