Management of preterm labor

Committee on Practice Bulletins-Obstetrics

ACOG Practice Bulletin No 127: Management of Preterm Labor, June 2012

Obstet Gynecol 2012;119:1308-17. Full text of ACOG Practice Bulletin available to ACOG members at http://www.acog.org/Resources_And_Publications/Practice_Bulletins/Committee_on_Practice_Bulletins_--_Obstetrics/Management_of_Preterm_Labor/

Preterm birth is the leading cause of neonatal mortality and the most common reason for antenatal hospitalization (1–4). In the United States, approximately 12% of all live births occur before term, and preterm labor preceded approximately 50% of these preterm births (5, 6). Although the causes of preterm labor are not well understood, the burden of preterm births is clear-preterm births account for approximately 70% of neonatal deaths and 36% of infant deaths as well as 25–50% of cases of long-term neurologic impairment in children (7–9). A 2006 report from the Institute of Medicine estimated the annual cost of preterm birth in the United States to be $26.2 billion or more than $51,000 per premature infant (10). However, identifying women who will give birth preterm is an inexact process. The purpose of this document is to present the various methods proposed to manage preterm labor and to review the evidence for the roles of these methods in clinical practice. Identification and management of risk factors for preterm labor are not addressed in this document.
Used with permission. Copyright the American College of Obstetricians and Gynecologists.

Management of preterm labor: Have we learned anything since 2003?

The answer is yes, with a few caveats.

In the last 9 years, we have learned at least 2 new things about the management of preterm labor or, really, about interventions for women likely to deliver early that reduce morbidity for their newborns. Sad but true, however, is that we really have not learned anything new that helps us prevent or delay preterm delivery. The other sad truth is that we are still employing useless interventions to attempt to delay preterm delivery and the American College of Obstetricians and Gynecologists (ACOG) continues to try to help us just stop, first with the recommendations in its 2003 practice bulletin and now by reaffirming that same information in the 2012 practice bulletin on the same subject.¹

First, the new things: Antenatal corticosteroids.

This is listed as a Level A recommendation in the 2012 bulletin.¹ A single course of corticosteroids is recommended for pregnant women between 24 and 34 weeks who are at risk of preterm delivery within 7 days. The reason for this recommendation, of course, is that numerous randomized trials and a Cochrane meta-analysis show a significant reduction in neonatal morbidity and mortality-including respiratory distress syndrome, necrotizing enterocolitis, and intraventricular hemorrhage-with corticosteroids.^2-4 New data from randomized trials also show that a single repeat course (2 doses) in women whose prior course was at least 7 days previously and who remain at risk of preterm delivery before 34 weeks significantly reduces neonatal morbidity.^5,6 This latter recommendation is listed as Level B in the 2012 bulletin.¹

Antenatal magnesium sulfate for fetal neuroprotection.

This intervention for fetal neuroprotection is new and listed as Level A¹ : Magnesium sulfate reduces the severity and risk of cerebral palsy in surviving infants if administered when birth is anticipated before 32 weeks.^7-11 It is also recommended that if a hospital elects to use magnesium sulfate for neuroprotection, guidelines be developed for inclusion criteria, treatment regimens, concurrent tocolysis, and monitoring in accordance with one of the larger trials. An excellent trial to use for possible guideline development is the Rouse trial.⁹

The other key Level A recommendation, which is similar between the 2 bulletins, is that any tocolysis is effective only for a short time (2 days), which reinforces that all we can really do is stop labor long enough to gain the neonatal benefit of antenatal corticosteroids and magnesium sulfate.¹