Tocolytic Therapy in Preterm Labor

Indications and Contraindications

Tocolytic therapy is recommended for a 32-week pregnant female with preterm labor to delay delivery for 48-72 hours, allowing for administration of antenatal corticosteroids and maternal transfer to an appropriate facility if needed, with contraindications including severe preeclampsia or eclampsia requiring immediate delivery, and mild preeclampsia may be a consideration for tocolytic therapy, as recommended by the American College of Cardiology and other guideline societies 1
Diagnosis of preterm labor, defined as regular contractions with cervical change, is crucial before initiating tocolytic therapy, according to the American Journal of Obstetrics and Gynecology 2
Contraindications for tocolytic therapy include severe preeclampsia or eclampsia, chorioamnionitis or intrauterine infection, fetal distress or non-reassuring fetal status, fetal demise or lethal fetal anomaly, significant maternal hemorrhage or unstable maternal condition, and advanced cervical dilation (>5 cm) or effacement, with hypotension, liver dysfunction, and concurrent use with magnesium sulfate being specific contraindications for certain tocolytics, as recommended by the American College of Cardiology and other guideline societies 1

Nifedipine is a first-line option due to ease of administration and favorable side effect profile, with a recommended dose of 10-20 mg orally, repeat in 30 minutes if needed, according to the European Heart Journal and the American College of Obstetricians and Gynecologists (ACOG) 1, 2, 3
Magnesium sulfate is an alternative if nifedipine is contraindicated, with a recommended dose of 4-6g loading dose, then 1-2g/hour maintenance, and has a dual benefit of tocolysis and fetal neuroprotection, but has contraindications including myasthenia gravis, renal failure, heart block or myocardial damage, and concurrent use with calcium channel blockers, as recommended by the European Heart Journal and the ACOG 1, 3
Indomethacin is not recommended at 32 weeks due to risk of premature ductal closure, and has contraindications including use beyond 48 hours, gestational age >32 weeks, renal dysfunction, platelet dysfunction or bleeding disorders, and gastrointestinal ulcerative disease, but is reasonable for gestations less than 32 weeks, as recommended by the European Heart Journal and the ACOG 1, 3

Vital signs, particularly BP and pulse, should be monitored during tocolytic therapy, according to the European Heart Journal and the ACOG 1, 2
Continuous electronic fetal monitoring is recommended during acute tocolysis, and for indomethacin, monitor for oligohydramnios and ductal constriction if used >48 hours, as recommended by the European Heart Journal and the ACOG 1, 2
Maintenance tocolysis beyond acute treatment has not been shown to improve outcomes, and antenatal corticosteroids should be administered concurrently with tocolysis, as recommended by the European Heart Journal and the ACOG 1, 3
Level 2 hospitals are designed to care for moderately ill newborn infants born at ≥32 weeks' gestation, infants weighing ≥1500g at birth with problems expected to resolve rapidly, and patients not anticipated to need subspecialty services urgently, according to the American Academy of Pediatrics guidelines 4
Infants born at <32 weeks' gestation or weighing <1500g should be cared for at a level III facility, based on evidence showing improved outcomes when very premature infants receive care at facilities with appropriate resources, as recommended by the American Academy of Pediatrics 4

Antenatal corticosteroids should be administered if gestational age is 23-34 weeks, as they significantly reduce death and neurodevelopmental impairment in infants born at 23-25 weeks, as recommended by the ACOG 3
Clear communication between referring and receiving facilities is essential for effective implementation of the risk transfer strategy, as stated by the ACOG 5
Hospitals without optimal resources should have established protocols for timely transport to ensure safe transfer of pregnant patients in labor to a facility with obstetric resources, as recommended by the ACOG 3
The primary goal of tocolytic therapy in preterm labor is to delay delivery long enough for safe maternal transfer, allow time for administration of interventions that improve neonatal outcomes, and ensure delivery occurs in a facility with appropriate maternal and neonatal care capabilities, as stated by the ACOG 3

The diagnosis of preterm labor may be complicated in women with skeletal dysplasia due to difficulty in assessing cervical dilation, as noted by the ACOG 2
Serial amnioinfusions and amniopatch are considered investigational and should only be used in clinical trial settings, according to the ACOG 6
The ACOG recommends against the use of antibiotics for preterm labor with intact membranes, except in cases of preterm premature rupture of membranes (PPROM) at 24 weeks and beyond 3, 6