What is the role of fetal therapy in the treatment of preterm labor?

Updated: Dec 17, 2018
  • Author: Michael G Ross, MD, MPH; Chief Editor: Carl V Smith, MD  more...
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Answer

The administration of glucocorticoids is recommended in the absence of clinical infection whenever the gestational age is between 24 and 34 weeks. An attempt should be made to delay delivery for a minimum of 12 hours to obtain clinical benefits of antenatal steroids.

Recent data also suggest that glucocorticoids (i.e., betamethasone) may be beneficial in pregnant women at high risk of late preterm birth (within 7 days), between 34 0/7 weeks and 36 6/7 weeks of gestation who have NOT received a prior course of antenatal corticosteroids. [28] Administration of betamethasone led to a significant decrease in respiratory complications and the need for respiratory support, though hypoglycemia was more common in the infants exposed to betamethasone 24.0% versus 14.9% (RR, 1.61; 95% CI, 1.38–1.88). [21]

Importantly, administration of late preterm glucocorticoids is not indicated in women with clinical chorioamnionitis, multiple gestations, or pregestational diabetes, and tocolysis should not be used in an attempt to delay delivery in order to administer glucocorticoids in the late preterm period, nor should an indicated late preterm delivery (e.g., preeclampsia with severe features) be postponed for corticosteroid administration.

The recommended dosage of betamethasone consists of two 12 mg doses 24 hours apart while four doses of 6 mg of dexamethasone should be administered at 6-hour intervals. Whenever the following clinical conditions exist, the glucocorticoid regimen may require modification:

  • In the presence of insulin-dependent or gestational diabetes, the provider should be prepared for control of blood sugars.

  • In the event of an acutely distressed fetus, indicative of fetal hypoxia, the use of prophylactic steroids should not delay the delivery of an acutely distressed fetus.

Although the use of repeated doses of glucocorticoids remains controversial, a meta-analysis concluded that repeated doses of prenatal corticosteroids in women who remained at risk for preterm birth 7 or more days after an initial course reduced the risk of their infants developing respiratory distress syndrome and reduced serious infant outcomes (relative risk 0.83 and 0.84, respectively). Treatment with repeat doses was associated with a reduction in mean birthweight of approximately 76 g; however, no differences in growth assessments or disabilities at early childhood were noted in follow-up. [29] In view of these conclusions, clinicians may consider use of a single repeated dose of glucocorticoids (rescue dose) at least 7-14 days from the initial treatment if the patient remains at significant risk for preterm delivery within the next 7 days, at a gestational age less 34 weeks.


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