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Practice Guidelines
The committee on Practice Bulletins-Obstetrics of the American College of Obstetricians and Gynecologists (ACOG) has issued new recommendations on assessing risk factors for preterm birth. ACOG Practice Bulletin No. 31, which replaces Technical Bulletin No. 206 issued in June 1995, appears in the October 2001 issue of Obstetrics and Gynecology. These recommendations discuss risk factors, markers for predicting preterm birth, and clinical considerations.
Diagnosis and Predicting Risk
According to ACOG, preterm labor is defined as regular contractions associated with cervical change before 37 weeks' gestation. Spontaneous preterm birth includes preterm labor, preterm spontaneous rupture of membranes, and cervical incompetence. The pathophysiologic events that trigger preterm birth are largely unknown but may include decidual hemorrhage (abruption), uterine overdistention, and hormonal changes possibly mediated by fetal or maternal stress. Certain bacterial infections also have been associated with preterm labor, including Ureaplasma urealyticum, Mycoplasma hominis, Gardnerella vaginalis, and Peptostreptococcus and Bacteroides species. These organisms are usually of low virulence, and it is unclear whether they are etiologic or associated with an acute inflammatory response of another etiology.
Predicting risk of preterm labor is only valuable if there is an available intervention that is likely to improve the situation. Even though maternal tocolytic and steroid therapies may prolong pregnancy and decrease morbidity and mortality, they should be limited to those with true preterm labor at high risk for spontaneous preterm birth because of possible fetal and maternal consequences. Identifying women at risk allows for appropriate transfer to a facility...