The grades of evidence (I-III) and levels of recommendations (A-C) are defined at the end of the "Major Recommendations."
The following recommendations are based on good and consistent scientific evidence (Level A):
- There are no clear "first-line" tocolytic drugs to manage preterm labor. Clinical circumstances and physician preferences should dictate treatment.
- Antibiotics do not appear to prolong gestation and should be reserved for group B streptococcal prophylaxis in patients in whom delivery is imminent.
- Neither maintenance treatment with tocolytic drugs nor repeated acute tocolysis improve perinatal outcome; neither should be undertaken as a general practice.
- Tocolytic drugs may prolong pregnancy for 2 to 7 days, which may allow for administration of steroids to improve fetal lung maturity and the consideration of maternal transport to a tertiary care facility.
The following recommendations are based on limited or inconsistent scientific evidence (Level B):
- Cervical ultrasound examination and fetal fibronectin testing have good negative predictive value; thus, either approach or both combined may be helpful in determining which patients do not need tocolysis.
- Amniocentesis may be used in women in preterm labor to assess fetal lung maturity and intra-amniotic infection.
- Bed rest, hydration, and pelvic rest do not appear to improve the rate of preterm birth and should not be routinely recommended.
Definitions:
Grades of Evidence
I Evidence obtained from at least one properly designed randomized controlled trial
II-1 Evidence obtained from well-designed controlled trials without randomization
II-2 Evidence obtained from well-designed cohort or case-control analytic studies, preferably from more than one center or research group
II-3 Evidence obtained from multiple time series with or without the intervention. Dramatic results in uncontrolled experiments also could be regarded as this type of evidence.
III Opinions of respected authorities, based on clinical experience, descriptive
studies, or reports of expert committees
Levels of Recommendations
Level A - Recommendations are based on good and consistent scientific evidence.
Level B - Recommendations are based on limited or inconsistent scientific evidence.
Level C - Recommendations are based primarily on consensus and expert opinion.
