Management of Preterm Labor Flashcards
Preterm birth
Birth between 20 0/7 weeks and 36 6/7 weeks of gestation
Preterm labor
Regular uterine contractions accompanied by a change in cervical dilation, effacement or both, or initial presentation with regular uterine contraction and dilation of at least 2 cm
Percentage of women with the clinical diagnosis of preterm labor who give birth in the next 7 days
10%
Therapeutic interventions associated with improved neonatal outcomes
antenatal corticosteroids and magnesium sulfate
Which tests can be used to stratify risk for preterm delivery in patients who present with preterm contractions?
fetal fibronectin testing and cervical length measurements are associated with preterm birth but the positive predictive value of these tests alone is poor and should not be used exclusively to direct management in the acute setting
Which patients with preterm labor are appropriate candidates for intervention?
Tocolytics
- at a gestational age at which a delay in delivery will provide benefit to the newborn
- Will benefit from the 48 hr effective window that tocolytics provide
- not at greater than 34 weeks gestation
Corticosteroids
- Not typically used in previability - exceptions may be following incidents which are known to induce preterm birth (abdominal surgery)
Tocolytics in preterm delivery guidelines
- Effective for up to 48 hrs
- not used in previability (due to risks of therapy to mother exceeding the small potential benefits to the fetus)
Contraindications to tocolysis
- IUFD
- Lethal fetal anomoly
- Nonreassuring fetal status
- Severe preeclampsia or eclampsia
- Maternal bleeding with hemodynamic instability
- Chorioamnionitis
- PPROM (in the absence of chorio, tocolysis may be used for maternal transport or steroid administration purposes)
- Maternal contraindications
Should women with preterm contractions but without cervical change be treated?
No, especially with < 2 cm dilation
Does the administration of antenatal corticosteroids improve neonatal outcomes? What are the recommendations?
Yes
- Single course of steroids for women 24-34 wks at risk of delivery in the next 7 days (including in women with ruptured membranes and twin gestation)
- May be considered in women at 23 weeks as well who are at risk in the next 7 days
Late preterm (34 0/7 wks - 36 6/7 wks) - data shows decrease in respiratory morbidity with steroids
Previable - based on family’s resuscitation desires
Beneficial effects of corticosteroids in preterm birth
Reduced:
- Respiratory distress syndrome
- intracranial hemorrhage
- necrotizing enterocolitis
- death
Indications for rescue course of steroids
Less than 34 wks, at risk of preterm delivery in the next 7 days, with prior course of steroids administered >14 days ago
- Can be given 7 days after initial course in certain cases.
- Lacking studies in the late preterm period
- Controversial in PPROM
- Given even if unlikely to receive full dose
Steroids and doses
Betamethasone - 2 12 mg doses intramuscularly given 24 hours apart
Dexamethasone - 4 6 mg doses intramuscularly every 12 hrs
- No benefit to accelerated dosing
What is the role for magnesium sulfate for fetal neuroprotection?
- Reduces the severity and risk of cerebral palsy in patients at <32 wks with risk of delivery
- No prolongation of pregnancy
- Increased incidence of minor maternal complications, but no increase in major maternal complications
Does tocolytic therapy improve neonatal outcomes?
No
Evidence-supported tocolytic agents
Beta-adrenergic receptor agonists, CCBs, and NSAIDs
Agents not supported by evidence
Magnesium sulfate, oxytocin antagonists, and transdermal nitroglycerin agents (maternal risk)
CCBs: Maternal side effects, fetal side effects, and contraindications
Maternal side effects: dizziness, flushing and hypotension; suppresion of HR, contractility and LVSP when used with Mg; elevated hepatic transaminases
Fetal side effects: none
Contraindications: hypotension and preload-dependent cardiac lesions (aortic insufficiency)
NSAIDs
Maternal side-effects: nausea, esophageal reflux, gastritis and emesis; platelet dysfunction is rarely an issue in women without an underlying bleeding disorder
Fetal side effects: in utero constriction of ductus arteriosis and oligohydramnios (most severe with >48 hr use)
- Necrotizing enterocolitis in preterm infants
- Patent ductus arteriosis in newborn
Contraindications: platelet dysfunction or bleeding disorder, hepatic dysfunction, gastrointestinal ulcerative disease, renal dysfunction, and asthma (in women with hypersensitivity to aspirin)
Beta-adrenergic receptor agonists
Maternal side-effects: tachycardia, hypotension, tremor, palpitations, SOB, chest discomfort, pulmonary edema, hypokalemia, and hyperglycemia
Fetal side effects: tachycardia
Contraindications: tachycardia-sensitive maternal heart disease and poorly-controlled DM
Magnesium sulfate
Maternal side-effects: flushing, diaphoresis, nausea, loss of DTRs, respiratory depression, cardiac arrest, decreased HR, contractility, LVSP, and neuromuscular blockade when used with CCBs
Fetal side-effects: fetal depression
Contraindications: myesthenia gravis
Pharmacologic treatment for uterine tachysystole
Terbutaline
Should tocolytics be used after acute therapy?
No, only atosiban (not yet FDA approved) has been shown to be better than placebo as a maintenance drug to prevent preterm birth
Is there a role for antibiotics in preterm labor?
No, antibiotics have actually been found to be associated with long-term harm in women with preterm labor and intact membranes
Is there a role for nonpharmacologic management of women with preterm contractions or preterm labor?
No
Is preterm labor managed differently in women with multiple gestations?
- Tocolytics have not been shown to be helpful and actually increase maternal complications in multifetal gestations
- Corticosteroids and magnesium sulfate are used the same as in singleton gestations.
