Uterine Activity Monitoring Research Articles

4 Prediction of preterm labour in multiple pregnancies

Various methods of predicting preterm labour in both singleton and multiple pregnancies have been studied including risk scoring systems, home uterine activity monitoring, cervical assessment and biochemical methods. In practice, risk scoring systems for preterm delivery perform poorly. Consensus in the literature regarding the usefulness of home uterine activity monitoring is lacking and well designed randomized controlled trials are required. Transvaginal ultrasound assessment of the cervix appears to have a role to play in the prediction of preterm labour. The presence of IFN in cervicovaginal fluid in the late second and early third trimesters is an important risk factor for preterm labour in asymptomatic women with multiple pregnancies. Preterm labour may be mediated in part by inflammatory cytokines. The measurement of these inflammatory cytokines in cervical secretions may also prove helpful in the prediction of preterm labour. It is anticipated that an improved ability to predict preterm labour in both singleton and multiple pregnancies will depend on increasing understanding of the condition's pathophysiology.

5 Prevention of preterm birth in multiple pregnancy

Preterm birth is the greatest threat to the infants in a multiple pregnancy. This chapter focuses on strategies that aim to prevent preterm birth and concentrates on the evidence derived from randomized clinical trials and systematic review of randomized clinical trials. The options to avoid a multiple pregnancy are briefly considered. Interventions that aim to prolong pregnancy, including prophylactic cervical cerclage, prophylactic tocolysis, home uterine activity monitoring and hospitalization for bed rest, are critically appraised, as are interventions that aim to improve the outcome of preterm birth. Interventions that require additional evaluation are highlighted.

Monitoring Women at Risk for Preterm Labor

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.

Identifying twin gestations at low risk for preterm birth with a transvaginal ultrasonographic cervical measurement at 24 to 26 weeks' gestation

Objective: Because twins are a high-risk group for preterm birth, many clinicians routinely use prophylactic interventions such as home bed rest, hospital bed rest, oral tocolytics, or home uterine activity monitoring to prevent preterm delivery. We sought to identify twin gestations at low risk for spontaneous preterm birth with transvaginal ultrasonography of the cervix to avoid the unnecessary use of prophylactic interventions in these pregnancies. Study Design: We measured cervical length at 24 to 26 weeks' gestation by transvaginal ultrasonography in women with twin gestations referred to our prematurity prevention clinic. Each delivery was classified as (1) spontaneous preterm birth <34 weeks' gestation, (2) delivery at ≥34 weeks' gestation with intervention, or (3) delivery at ≥34 weeks' gestation without intervention. Intervention included strict bed rest at home or in the hospital, either parenteral or oral tocolysis, or both, or home uterine activity monitoring. Indicated preterm deliveries and patients with cerclage were excluded from this analysis. The ability of transvaginal cervical length to predict women who would deliver at ≥34 weeks without intervention was evaluated. A cervical length of 35 mm was chosen by scatter diagram as the best cutoff to discriminate between the group delivered at term without intervention and the other two groups. Results: Of 85 women with twin gestations who underwent ultrasonographic cervical length measurements at 24 to 26 weeks' gestation, 17 had spontaneous preterm birth at <34 weeks, 23 were delivered at ≥34 weeks but required intervention, and 45 were delivered at ≥34 weeks without intervention. The mean cervical length for those delivered at ≥34 weeks' gestation without intervention (36.4 ± 5.8 mm) was significantly greater ( p < 0.0001) than the mean for those delivered preterm (27.4 ± 8.5) and those delivered at ≥34 weeks' gestation who required intervention (27.7 ± 10.5 mm). The sensitivity, specificity, and positive and negative predictive values of a cervical length >35 mm for predicting delivery at ≥34 weeks' gestation are 49%, 94%, 97%, and 31%, respectively. Conclusion: A transvaginal ultrasonographic measurement of the cervix of >35 mm at 24 to 26 weeks in twin gestations can identify patients who are at low risk for delivery before 34 weeks' gestation.

A validation study of home uterine activity monitoring technology in Western Australia.

Home uterine activity monitoring has been developed as an 'early warning' device to detect premature uterine activity, thereby encouraging earlier referral and tocolysis of women at risk of preterm delivery. This ambulatory monitoring system, utilizing a ring-guard tocodynamometer, was piloted in Western Australia to determine if it can reliably record and transmit antenatal uterine activity data in an Australian environment. Pregnant women were readily able to correctly apply and use the ambulatory monitoring device. The information collected was able to be transmitted using standard Australian telecommunications systems within our hospital environment. Validation studies with the ambulatory monitor and current external tocodynamometry hardware were performed. The ring-guard tocodynamometer detected more uterine activity at gestations less than 32 weeks compared with conventional external tocodynamometers. As term approached, however, the sensitivity of the ring-guard tocodynamometer decreased. A cross-sectional profile of antenatal uterine activity was developed for women at low risk of delivering preterm. A gradual increase in the number, duration and amplitude of uterine contractions as pregnancy advanced was observed.

Correlation of antepartum uterine activity and cervical change in twin gestation.

To determine the correlation between quantitative measurements of antepartum uterine activity and cervical change twin gestations. Forty women from our Twin Clinic constituted the study group. Participants had a cervical examination each week between 20 and 37 weeks gestation and a cervical score (CS) was calculated as follows: CS = cervical length (cms)-cervical dilation (cms) at the internal os. The women also performed blinded home uterine activity monitoring (HUAM) for a mean of 7.0 + 3.0 hrs/wk (+SD). Uterine activity was expressed as mean number of contractions/hour/week gestation based on the average of three independent reviewers. CS was determined by a single clinician unaware of the HUAM recordings. A significant change in the CS was defined as a reduction of at least 0.5 from the preceding week. Correlation coefficients were used to determine the association between uterine activity and change in the cervical score. Twin pregnancy was characterized by a rise from 0.2 + .03 contractions/hr at 20 weeks to 3.2 + 2.4 contractions/hr at 37 weeks gestation. CS fell from a mean of 2.6 + 0.2 at 20 weeks to -2.1 + 0.9 at 37 weeks gestation. There was a significant negative correlation (-0.317, p < .0001) between increasing uterine activity and decreasing CS. There were significantly more (p < .002) contractions during the 7 days preceding a significant reduction in CS (3.3 + 3.5 contractions/hr) than when the CS was unchanged (1.6 +/- 1.5 contractions/hr). In twin gestations, an increasing frequency of uterine contractions is strongly correlated with quantifiable cervical change between 20-37 weeks gestation. Persistent daytime contraction frequencies of > 3/hr represent a risk factor for cervical dilation and/or effacement.

Multicenter randomized clinical trial of home uterine activity monitoring: Pregnancy outcomes for all women randomized

OBJECTIVE: Our purpose was to evaluate the impact of home uterine activity monitoring on pregnancy outcomes among women at high risk for preterm labor and delivery. STUDY DESIGN: Women at high risk for preterm labor at three centers were randomly assigned to receive high-risk prenatal care alone (not monitored) or to receive the same care with twice-daily home uterine activity monitoring without increased nursing support (monitored). There were 339 women with singleton gestations randomized with caregivers blinded to group assignment. The two groups were medically and demographically similar at entry into the study. RESULTS: Women in the monitored group had prolonged pregnancy survival ( p = 0.02) and were less likely to experience a preterm delivery (relative risk 0.59; p = 0.04). Infants born to monitored women with singleton gestations were less likely to be of low birth weight (<2500 gm; relative risk 0.47, p = 0.003), and were less likely to be admitted to a neonatal intensive care unit (relative risk 0.5, p = 0.01). CONCLUSION: These data show, among women with singleton gestations at high risk for preterm delivery, that the use of home uterine activity monitoring alone, without additional intensive nursing care, results in improved pregnancy outcomes, including prolonged gestation, decreased risk for preterm delivery, larger-birth-weight infants, and a decreased need for neonatal intensive care. (Am J Obstet Gynecol 1996;175:1281-5.)

Prematurity: Assessment of uterine activity

Preterm delivery, and the complications associated with it, remains the most significant cause of perinatal morbidity and mortality in normally-formed babies. The incidence of preterm delivery remains constant at 6--10%, these deliveries being associated with up to 75% of neonatal mortality in the genetically normal fetus. Assessment of uterine activity is of critical importance in both the diagnosis and subsequent management of premature labour. Premature babies are particularly vulnerable to the stress of labour. Monitoring of both the fetal heart and uterine activity patterns assists the clinician in the management of labour. It allows early detection of abnormalities of the fetal heart rate, showing their relationship to uterine activity. Use of uterine activity monitoring when labour is augmented increases the efficiency and safety of oxytocin use. The methods used for the monitoring of uterine activity leading up to, and in, labour vary from clinical palpation of the uterus to the use of sophisticated electronic monitoring equipment. The choice of method employed is determined by the clinical situation, the availability of suitable equipment and the monitoring protocol of the obstetric unit concerned. The widespread introduction and use of electronic fetal monitoring devices, most of which provide some form of uterine activity assessment, has increased our knowledge of the dynamics of labour.

Preterm labour and delivery.

Preterm birth is a major cause of perinatal morbidity and mortality. It accounts for 5-10% of all births, and any treatment to prevent it could have a profound effect on neonatal outcome in both human and economic terms. The pathogenesis of both term and preterm birth remain poorly understood. Our ability to predict those at risk of preterm labour is also inaccurate, despite the creation of scoring systems, uterine activity monitoring, cervical ultrasound and several biochemical markers. Current drug therapies for preterm labour have not been shown in randomised controlled trials to significantly affect perinatal morbidity and mortality. Furthermore, most are associated with significant maternal or fetal side effects. Nitric oxide (NO) is a potent smooth muscle relaxant, produced when NO synthase acts on the amino acid L-arginine. Its presence has been demonstrated in human myometrium. We have conducted an observational study which has suggested that glyceryl trinitrate (GTN), and NO donor, may be effective in prolonging gestation. A randomised trial comparing GTN to intravenous ritodrine is currently recruiting patients; results will be available in the Spring of 1997. Few side effects have so far been encountered. Evidence suggests that GTN, an NO donor, should be a safe and effective tocolytic and early observations are encouraging; randomised trials currently underway should determine the significance of this breakthrough in the management of preterm labour.

Accuracy of maternal perception of preterm uterine activity

OBJECTIVE: Our purpose was to compare the accuracy of maternal perception of preterm uterine activity by self-palpation versus home uterine activity monitoring. STUDY DESIGN: A total of 72,962 uterine activity records of 778 women receiving home uterine activity monitoring services were analyzed. Simultaneously with home uterine activity monitoring, the women indicated by an electronic marker when they felt a ”contraction” through self-palpation. The perceptions of the women were compared to the tocodynamometrically measured uterine activity. RESULTS: Using self-palpation, women correctly identified 17.2% of contractions recorded by tocodynamometry. Overall mean percent correct correlation per patient was only 14.1%. Patients missed an average of 85.7% of their contractions. Patients incorrectly perceived contractions that were not present an average of 40.3% of the time. Singleton gestations had significantly better correct correlations than twin gestations. Multiparous women had improved correlations compared with primiparous women. No significant correlation was found between maternal perceptive ability and gestational age. CONCLUSION: Women were unable to perceive accurately the presence or absence of preterm uterine activity through self-palpation compared with simultaneous measurement by home uterine tocodynamometry. (A M J O BSTET G YNECOL 1996;174:672-5.)

Current Status of Home Uterine Activity Monitoring

Current Status of Home Uterine Activity Monitoring

A metaanalysis of home uterine activity monitoring

OBJECTIVE: Our purpose was to assess by metaanalysis the evidence from randomized clinical trials regarding home uterine activity monitoring. STUDY DESIGN: Six randomized controlled trials of home uterine activity monitoring, the same six trials reviewed by the U.S. Preventive Services Task Force on home uterine activity monitoring, were studied. Data were extracted from published reports of the six trials. In addiiton, unpublished data were obtained by personal communication from the trials' principal investigators. Insofar as possible, the principle of intention-to-treat was maintained. Data regarding twins were handled by use of numbers of pregnancies rather than numbers of infants as sample sizes. Stratified metanalysis were conducted according to whether the trial did or did not control in study design for the nursing contact factor that accompanies home uterine activity monitoring. In addition, stratified metaanalysis were conducted for singleton and twin pregnancies. The four outcomes investigated were incidence of preterm birth, incidence of preterm labor combined with cervical dilatation >2 cm, infant referral to the intensive care unit, and mean birth weight. RESULTS: Overall, for all pregnancies home uterine activity monitoring was associated with a statistically significant reduction of 52% in risk of preterm labor combined with cervical dilatation >2 cm (relative risk = 0.48, p = 0.001) and a statistically significant increase of 86 gm in mean birth weight ( p = 0.038). When stratified by singleton or twin pregnancy, the pooled results generally differed by strata. Among singleton pregnancies, home uterine activity monitoring was associated with a statistically significant reduction of 24% in risk of preterm birth (relative risk 0.76, p = 0.037) and a statistically significant increase of 126 gm in mean birth weight ( p = 0.009). Among twin pregnancies, there was a statistically significant effect of home uterine activity monitoring with a reduction of 56% in risk of preterm labor combined with cervical dilatation >2 cm (relative risk 0.44, p = 0.005). There were no statistically significant effects found overall and in any stratum with regard to infant referral to the intensive care unit. Metaanalysis of studies that controlled in design for the nursing contact factor that accompanies home uterine activity monitoring showed either no difference or stronger pooled effects compared with metaanalyses of those studies that did not control for nursing contact. This suggest that the potential bias attributed to the nursing contact feature that accompanies home uterine activity monitoring is not as appreciable as home uterine activity monitoring critics have suggested. CONCLUSIONS: Metaanalysis of existing clinical trial evidence regarding home uterine activity monitoring reveals statistically significant benefits of home uterine activity monitoring. Of the outcomes investigated, home uterine activity monitoring is associated with reductions in risks of preterm birth (in singleton pregnancies only) and preterm labor combined with cervical dilatation >2 cm, as well as with increased mean birth weight (in singleton pregnancies only).

A multicenter randomized controlled trial of home uterine monitoring: Active versus sham device

OBJECTIVE: Our purpose was to determine the efficacy of a home uterine activity monitoring system for early detection of preterm labor and reduction of preterm birth. STUDY DESIGN: A randomized, controlled, double-blinded trial was performed in which pregnant women between 24 and 36 weeks' gestation and at high risk for preterm labor or birth were assigned to receive twice daily nursing contact and home uterine activity monitoring with either active (data revealed) or sham (data concealed) devices. Study end points included mean cervical dilatation and its mean change from a previous visit at preterm labor diagnosis, preterm birth rate, and infant outcomes. Analysis of variance or logistic models including terms for site and group-by-site interaction effects were constructed for all variables. RESULTS: Of 1355 patients enrolled, 1292 were randomized, 1165 used home uterine activity monitoring devices, and 842 (72.3%) completed the study. Both device groups had similar demographics, enrollment and delivery gestational ages, discontinuation rates, risk factors, birth weights, cervical dilatation at enrollment and at preterm labor diagnosis, change in cevical dilatation at preterm labor diagnosis, rates of preterm labor and birth, and neonatal intensive care requirements. Power to detect a difference in cervical dilatation ≥1 cm at diagnosis of preterm labor was 0.99 for all risk factors. CONCLUSIONS: Uterine activity data obtained from home uterine activity monitoring, when added to daily nursing contact, were not linked to earlier diagnosis of preterm labor or lower rates of preterm birth or neonatal morbidity in pregnancies at high risk for preterm labor and birth.

A randomized multicenter trial assessing a home uterine activity monitoring device used in the absence of daily nursing contact

OBJECTIVE: To evaluate the effectiveness of home uterine activity monitoring in the early detection of preterm labor among women with a history of preterm delivery. STUDY DESIGN: Two hundred eighteen women from four centers were prospectively randomized to routine high-risk prenatal care alone (not monitored) or to the same prenatal care with twice-daily home uterine activity monitoring without daily nursing support (monitored). All women had a history of preterm delivery. The primary study end point was cervical status as measured by cervical dilatation at the time of diagnosis of preterm labor. RESULTS: The two study group populations at entry into the study were similar in medical and demographic characteristics. Of 187 women completing the trial, 21 (24.4%) of the women in the monitored group ( n = 86) and 22 (21.8%) of the women in the unmonitored (control) group ( n = 101) experienced preterm labor (not significant). Mean cervical dilatation at the time of diagnosis of preterm labor was 1.7 cm in the monitored group and 2.8 cm in the unmonitored group ( n = 0.004). A total of 52.4% of the women in the monitored group had a cervical dilatation of <2 cm when preterm labor was detected, compared with 18.2% of the women in the unmonitored group ( p = 0.019). The median duration of gestation after diagnosis of preterm labor was 21.0 days for the monitored group and 3.0 days for the unmonitored group ( p = 0.016). CONCLUSION: The diagnosis of preterm labor for women using home uterine activity monitoring without daily nursing contact was detected with less cervical dilatation than found in those women not monitored. This earlier detection of preterm labor demonstrates the utility and effectiveness of home uterine activity monitoring devices and may lead to improved neonatal outcomes.

Routine home uterine activity monitoring in patients with a cervical cerclage, is there an impact on outcome: [formula omitted], M. Nazir. Pennsylvania Hospital, Philadelphia, Pennsylvania

Routine home uterine activity monitoring in patients with a cervical cerclage, is there an impact on outcome: [formula omitted], M. Nazir. Pennsylvania Hospital, Philadelphia, Pennsylvania

The Role of Obstetrical Medical Technology in Preventing Low Birth Weight

Technology plays an important role in the practice of medicine, and it is essential that controlled clinical trials be conducted before new technologies are widely disseminated. In this article, information from the medical literature is summarized and critiqued for several common obstetric technologies which are aimed at reducing the incidence or sequelae of low birth weight and preterm birth. These technologies include home uterine activity monitoring, tocolytic drugs to suppress uterine contractions, corticosteriods to accelerate fetal lung maturity, bed rest to prevent preterm delivery, delivery methods, multifetal pregnancy reduction, and cervical cerclage. A major challenge to the practice of medicine is to find effective ways to modify physician behavior to encourage the use of proven, effective technologies, and discourage the use of unproven, ineffective technologies. Despite widespread use, most obstetrical technologies appear to have had little impact on reducing the incidence of low birth weight or preterm births, as rates of low birth weight and preterm birth have not decreased appreciably in the past 25 years. Uncovering the basic mechanisms responsible for the onset of preterm labor will undoubtedly facilitate the discovery of new technologies to prevent low birth weight and preterm births.

Risk Management and Legal Issues in Home Care: The Utilization of Nursing Staff

A sound, integrated risk-management program in home health care can significantly reduce the potential for inclusion in lawsuits. Focusing on two clinical patient care situations (the pregnant woman receiving home uterine activity monitoring and the female patient with acquired immune deficiency syndrome), this article presents the components of risk management and their practical implications for the delivery of nursing care in the home.

Defining reducible risk

In maternity care, costly high-technology interventions that have never been shown to be clinically effective continue to be used in the United States, while inexpensive and effective low-technology interventions continue to be underused. Three high-technology approaches to risk reduction-electronic fetal monitoring, cesarean section, and home uterine activity monitoring are contrasted with three low-technology approaches-prenatal care, smoking cessation, and nutrition supplementation. These technologies are examined in terms of current controversies over their safety, efficacy, and cost-effectiveness. Examination of these controversies illustrates how the medical technology industry, the regulatory process, and systems of social stratification contribute to social and cultural constructions of what are regarded as reducible birth risks.

Reanalysis of a Muitireported Trial on Home Uterine Activity Monitoring

A randomized multicenter study of home uterine activity monitoring using the "Term Guard," is widely cited in support of the Term Guard monitoring system. Critical appraisal of the data in the six reports of the study showed that all reports scored poorly on avoidance of allocation, exclusion, and assessment bias. In all of them the numbers of women for whom outcomes were reported were different, and none provided information on infant outcomes. Comparison of analyses and subanalyses showed inconsistencies that defied the laws of arithmetic. Reanalysis of the data, as well as could be done from the available information, showed that use of the Term Guard system was compatible with both an increase and a decrease in the frequency of preterm delivery (95% CI +2.2% to -16.5%). It is concluded that the reports of the multicenter study contain such high potential for bias and so many internal inconsistencies that they should be dismissed entirely.

Home Uterine Activity Monitoring for Preterm Labor

PRETERM birth is a leading cause of perinatal morbidity and mortality in the United States. Preterm neonates are thought to account for at least half of the mortality and morbidity among newborns without congenital anomalies.1These conditions represent a leading cause of years of potential life lost before the age of 65 years. Preterm births generate large societal costs by requiring neonatal intensive care and long-term treatment for complications. Both primary and secondary preventive measures have been proposed for the prevention of prematurity. Primary prevention includes efforts to reduce risk factors for prematurity, such as cessation of tobacco, alcohol, and other drug use, and programs to improve nutrition, socioeconomic conditions, and prenatal care. Secondary prevention involves the early detection and treatment of preterm labor. It has been suggested that the risk of preterm birth can be reduced significantly by the prompt initiation of treatment, which includes rest, hydration, and