Labor and Birth · Physiologic Birth
Katz M et al., 1986 · Obstet Gynecol
Effective tocolytic therapy depends on the ability to make an early diagnosis of preterm labor. This study was designed to assess whether daily ambulatory home monitoring of uterine activity could facilitate early diagnosis of preterm labor. Of 76 patients at high risk for preterm labor who used daily ambulatory tocodynamometry, approximately half developed preterm labor. Evaluation when the diagnosis of preterm labor was first established has shown that in 8% of the patients the cervix was dilated more than 2 cm, shortened to less than 0.5 cm in 23%, and the fetal membranes were intact in all subjects. The same evaluation in 76 nonrandom contemporary controls matched for risk factors, maternal age, and parity has shown that more than 50% had a cervix dilated more than 2 cm, 38% had a cervix shorter than 0.5 cm, and 24% had rupture of the fetal membranes. Ultimately, 88% of the monitored patients and 59% of controls delivered at term. Comparisons between these groups indicate that intermittent home tocodynamometry may indeed be useful in making the early diagnosis of preterm labor.
Preterm Birth · Prediction
Hobel CJ et al., 1994 · Am J Obstet Gynecol
The primary objective of this prospective study was to test whether preterm birth prevention education plus increased clinic visits and selected prophylactic interventions reduce preterm birth. Eight West Los Angeles prenatal county clinics, comparable with respect to selected demographics, were randomized to be either experimental or control clinics. High-risk patients in all clinics were identified with a risk scoring system derived from a similar population. High-risk patients (N = 1774) in experimental clinics were offered a program of education and more frequent visits and were randomized to receive various secondary intervention protocols in addition to the basic interventions of education and more frequent visits. Control clinic patients (N = 880) received standard county care. Preterm birth rates were 19% lower among the experimental high-risk patients (7.4% vs 9.1%), and differences were significant (p < 0.05) when preterm risk was taken into account. There was no evidence to suggest that the secondary interventions provided added benefit over the primary intervention protocol of preterm birth prevention education and increased visits. The 19% reduction in preterm birth rate observed in the experimental clinics suggest an overall program benefit from a protocol that offered education, more frequent visits, and greater attention given to patients while the selected interventions were applied.
Preterm Birth · Prediction
Dyson DC et al., 1998 · N Engl J Med
Preterm birth is a major cause of perinatal morbidity and mortality. Whether the rate of preterm birth can be reduced by frequent contact between nurses and pregnant women or home monitoring of uterine activity is not known. We randomly assigned 2422 pregnant women with known risk factors for preterm labor (including 844 women who were pregnant with twins) to receive education and to have one of the following: weekly contact with a nurse, daily contact with a nurse, or daily contact with a nurse and home monitoring of uterine activity. The nurses elicited the women's own assessments of their symptoms and signs of preterm labor. The primary end point was the incidence of birth at less than 35 weeks' gestation. Secondary end points included cervical status at the time preterm labor was diagnosed and birth weight. There were no significant differences among the groups in the incidence of birth at less than 35 weeks (14 percent in the weekly-contact group, 13 percent in the daily-contact group, and 14 percent in the home-monitoring group), in the mean amount of cervical dilatation at the time preterm labor was diagnosed (1.8 cm, 1.5 cm, and 1.4 cm, respectively), or in such neonatal outcomes as birth weights of less than 1500 g or less than 2500 g. However, daily contact with a nurse increased the mean number of unscheduled visits to obstetricians (1.2 in the weekly-contact group, 1.8 in the daily-contact group, and 2.3 in the home-monitoring group) and the proportion of women who received prophylactic tocolytic drugs (12 percent, 14 percent, and 19 percent, respectively). Women who have daily contact with a nurse, with or without home monitoring of uterine activity, have no better pregnancy outcomes than women who have weekly contact with a nurse.
Preterm Birth · Prediction
Owen J et al., 2001 · JAMA
Although shortened cervical length has been consistently associated with spontaneous preterm birth, it is not known when in gestation this risk factor becomes apparent. To determine whether sonographic cervical findings between 16 weeks' and 18 weeks 6 days' gestation predict spontaneous preterm birth and whether serial evaluations up to 23 weeks 6 days' gestation improve prediction in high-risk women. DESIGN, SETTING, Blinded observational study performed between March 1997 and November 1999 at 9 university-affiliated medical centers in the United States in 183 women with singleton gestations who previously had experienced a spontaneous birth before 32 weeks' gestation. Certified sonologists performed 590 endovaginal sonographic examinations at 2-week intervals. Cervical length was measured from the external os to the functional internal os along a closed endocervical canal. Funneling and dynamic cervical shortening were also recorded. Spontaneous preterm birth before 35 weeks' gestation, analyzed by selected cutoff values of cervical length. Forty-eight women (26%) experienced spontaneous preterm birth before 35 weeks' gestation. A cervical length of less than 25 mm at the initial sonographic examination was associated with a relative risk (RR) for spontaneous preterm birth of 3.3 (95% confidence interval [CI], 2.1-5.0; sensitivity = 19%; specificity = 98%; positive predictive value = 75%). After controlling for cervical length, neither funneling (P =.24) nor dynamic shortening (P =.054) were significant independent predictors of spontaneous preterm birth. However, using the shortest ever observed cervical length on serial evaluations, after any dynamic shortening, the RR of a cervical length of less than 25 mm for spontaneous preterm birth increased to 4.5 (95% CI, 2.7-7.6; sensitivity = 69%; specificity = 80%; positive predictive value = 55%). Compared with a single cervical measurement at 16 weeks' to 18 weeks 6 days' gestation, serial measurements at up to 23 weeks 6 days significantly improved the prediction of spontaneous preterm birth in a receiver operating characteristic curve analysis (P =.03). Cervical length assessed by endovaginal sonography between 16 weeks' and 18 weeks 6 days' gestation, augmented by serial evaluations, predicts spontaneous preterm birth before 35 weeks' gestation in high-risk women.
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