What are the criteria for use of tocolytic therapy to treat preterm labor?

Updated: May 04, 2021
  • Author: Michael G Ross, MD, MPH; Chief Editor: Carl V Smith, MD  more...
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Criteria that indicate consideration of tocolytic therapy include more than 6 contractions per hour resulting in a demonstrated cervical change or presumed prior cervical change (transvaginal cervical length < 2.5 cm, >50% cervical effacement, or cervical dilation ≥2 cm). If contractions are present without cervical change, management options include continued observation or therapeutic sleep (eg, morphine sulphate 10-15 mg subcutaneous).

When using strict criteria in women at 24 0/7 to 33 6/7 weeks’ gestation for “false preterm labor” (one contraction or less in 10 min, cervical dilation < 2 cm, and no evidence of cervical change over 2 h of observation), Chao et al demonstrated that these patients had a greater incidence of late preterm (34-36 weeks’ gestation) but not early preterm delivery (< 34 weeks’ gestation), compared with a control obstetric population. [24] However, those patients with cervical dilation of 1 cm were more likely to delivery prior to 34 weeks’ gestation. Although this study provides some guidance as to management, a negative FFN result and/or evidence of abated contractions may be of additional value in discharging patients with false preterm labor. In addition, measures of absolute or change in cervical length (effacement), in addition to dilation, may be of value in discriminating true versus false preterm labor.

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