OGCO-C2.9 Tocolytic therapy in premature labor

Question 1

When is suppression of labor not indicated?

Answer 1

• Gestation >34 weeks
• Fetal death in utero
• Fetal malformation where palliative care is planned
• Suspected fetal compromise as determined by ultrasound or CTG warranting delivery
• Placental abruption
• Chorioamnionitis
• Pre-eclampsia

Question 2

What is the aim of tocolytics?

Answer 2

Used to suppress uterine contractions for women in preterm labor. The aims of tocolysis is to delay delivery, in the absence of signs of maternal and/or fetal distress, for at least 48 hours to enable the effect of corticosteroid to enhance pulmonary maturation and for intrauterine transfer if requested by paeds. And where indicated and feasible, to delay delivery until the fetus has reached a gestation when the perinatal survival is reasonable.

Question 3

What are the 3 main forms of tocolytic therapy?

Answer 3

• CCB
• Oxytocin receptor
• Sympathomimetics

Question 4

What is 1st line tocolytic agent?
Dosage and maintenance?

Answer 4

Nifedipine: benefits over betamimetics with respect to prolongation of pregnancy, serious neonatal morbidity and maternal AE.

Acute tocolysis: check baseline BP, RR, temp and fetal heart rate. 20mg orally stat followd by 20mg orally after 30 mins if contractions persist, followed by slow release form 20mg orally after 30 mins if contractions persist.

Maintenance tocolysis (if indicated): after 48 hours of acute tocolysis (long acting nifedipine 40-60mg orally per day)

Question 5

What to monitor when using nifedipine for tocolysis?
When to stop treatment?

Answer 5

Monitoring
* Continuous CTG
* BP/P every 15 mins for the first hour, then every 30 mins for the second hour. Hourly in the first 24 hours, then four hourly when on maintenance dose
* Temp every 4 hours

Indications to stop treatment
* Maternal tachycardia >120bpm
* Cannot tolerate side effects of nifedipine
* Severe hypotension (stop treatment and start iv rehydration or normal saline or Hartmanns solution)

Question 6

What are the contraindications to use of nifedipine as tocolytic?

Answer 6

• Allergic to nifedipine
• Significant maternal cardiac disease - Hypotension
• Hepatic dysfunction
• Concurrent use of i.v. betamimetics
• Concurrent use of transdermal nitrates (GTN) or antihypertensive medication - Concurrent use of MgSO4
• (If women on high dose nifedipine (160mg/day) require concomitant infusion of MgSO4 in a conventional 4-6g i.v. bolus, there is a risk of significant hypotension. The risk is reduced by using a continuous infusion of MgSO4 in 1g/hr)

Question 7

What are the AE of nifedipine?

Answer 7

• Hypotension (in normotensive patients, the effects of nifedipine on blood pressure are
  minimal)
• Tachycardia, palpitation
• Flushing, Headache, dizziness
• Nausea
• Dyspnoea

Question 8

What is 2nd line tocolytic agent?
When is it indicated to use?

Answer 8

Atosiban (oxytocin antagonist)

Considered when
* In utero transfer of patients having preterm labor, already started on atosiban at other private/public hospitals
* Failed tocolysis with CCB
* Interolable side effects of other tocolytic drugs

Question 9

What is the 3rd line tocolytic agent?

Answer 9

Terbutaline

Question 10

Benefits of antenatal steroid injection?

Answer 10

• Significant reduction in rates of perinatal death, neonatal death, respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis and need for mechanical ventilation

Question 11

What is the precaution of using neonatal steroids?

Answer 11

• PPROM: observe for signs of infection
• Early preterm: single repat course of antenatal steroids if preterm birth does not occur within 7 days after the initial dose, and a subsequent clinical assessment demonstrates that there is a high risk of preterm birth in the next 7 days. Single use steroids –> less RDS and surfactant use and fewer serious morbidities.
• Maternal infection: for women with clinical sepsis or systemic infection