Monitoring women at risk for preterm labor

Biomarkers for Preterm Delivery

Preterm birth occurring before the thirty-seventh gestational week complicates 4.5%-18% of pregnancies worldwide. The pathogenesis of spontaneous preterm delivery is not fully understood. Among the factors held to be responsible for its pathogenesis, the most emphasized is the inflammatory process. Studies in terms of the prediction of preterm delivery are basically divided into 3 categories: 1) Prediction in pregnant women who are asymptomatic and without risk factors, 2) Prediction in pregnant women who are asymptomatic and have risk factors, 3) Prediction in symptomatic pregnant women who have threatened preterm labour. In this chapter, the topic of biomarkers in relation to preterm delivery is discussed. The most commonly used markers in published studies are fetal fibronectin, cervical pIGFBP-1 and cervical length measurement by transvaginal ultrasound. For prediction in symptomatic pregnant women applying to the hospital with threatened preterm labour, the markers used are fetal fibronection, insulin-like growth factors (IGFs) and inflammatory markers. Preterm labour prediction with markers checked in the first and second trimesters are fetal fibronection, insulin-like growth factors (IGFs), micro RNAs, progesterone, circulating microparticles (CMPs), inflammatory markers, matrix metalloproteinases, aneuploidy syndrome screening test parameters and other hormones.

Prediction and Prevention of Spontaneous Preterm Birth: ACOG Practice Bulletin, Number 234

Preterm birth is among the most complex and important challenges in obstetrics. Despite decades of research and clinical advancement, approximately 1 in 10 newborns in the United States is born prematurely. These newborns account for approximately three-quarters of perinatal mortality and more than one half of long-term neonatal morbidity, at significant social and economic cost (1-3). Because preterm birth is the common endpoint for multiple pathophysiologic processes, detailed classification schemes for preterm birth phenotype and etiology have been proposed (4, 5). In general, approximately one half of preterm births follow spontaneous preterm labor, about a quarter follow preterm prelabor rupture of membranes (PPROM), and the remaining quarter of preterm births are intentional, medically indicated by maternal or fetal complications. There are pronounced racial disparities in the preterm birth rate in the United States. The purpose of this document is to describe the risk factors, screening methods, and treatments for preventing spontaneous preterm birth, and to review the evidence supporting their roles in clinical practice. This Practice Bulletin has been updated to include information on increasing rates of preterm birth in the United States, disparities in preterm birth rates, and approaches to screening and prevention strategies for patients at risk for spontaneous preterm birth.

Multifractal analysis of uterine electromyography signals to differentiate term and preterm conditions

In this study, an attempt has been made to identify the origin of multifractality in uterine electromyography signals and to differentiate term (gestational age > 37 weeks) and preterm (gestational age ≤ 37 weeks) conditions by multifractal detrended moving average technique. The signals obtained from a publicly available database, recorded from the abdominal surface during the second trimester, are used in this study. The signals are preprocessed and converted to shuffle and surrogate series to examine the source of multifractality. Multifractal detrended moving average algorithm is applied on all the signals. The presence of multifractality is verified using scaling exponents, and multifractal spectral features are extracted from the spectrum. The variation of multifractal features in term and preterm conditions is analyzed statistically using Student's t-test. The results of scaling exponents show that the uterine electromyography or electrohysterography signals reveal multifractal characteristics in term and preterm conditions. Further investigation indicates the existence of long-range correlation as the primary source of multifractality. Among all extracted features, strength of multifractality, exponent index, and maximum and peak singularity exponents are statistically significant ( p < 0.05) in differentiating term and preterm conditions. The coefficient of variation is found to be lower for strength of multifractality and peak singularity exponent, which reveal that these features exhibit less inter-subject variance. Hence, it appears that multifractal analysis can aid in the diagnosis of preterm or term delivery of pregnant women.

Home uterine monitoring for detecting preterm labour

BACKGROUND

To reduce the morbidity and mortality associated with preterm birth, home uterine activity monitoring aims for early detection of increased contraction frequency, and early intervention with tocolytic drugs to inhibit labour and prolong pregnancy. However, the effectiveness of such monitoring is disputed.

OBJECTIVES

To determine whether home uterine activity monitoring is effective in improving the outcomes for women and their infants considered to be at high risk of preterm birth, when compared with care that does not include home uterine activity monitoring.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 June 2016), CENTRAL (Cochrane Library 2016, Issue 5), MEDLINE (1966 to 28 June 2016), Embase (1974 to 28 June 2016), CINAHL (1982 to 28 June 2016), and scanned reference lists of retrieved studies.

SELECTION CRITERIA

Randomised control trials of home uterine activity monitoring, with or without patient education programmes, for women at risk of preterm birth, compared with care that does not include home uterine activity monitoring.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risks of bias, extracted data and checked them for accuracy. We did not attempt to contact authors to resolve queries. We assessed the evidence using the GRADE approach.

MAIN RESULTS

There were 15 included studies (6008 enrolled participants); 13 studies contributed data. Women using home uterine monitoring were less likely to experience preterm birth at less than 34 weeks (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.62 to 0.99; three studies, 1596 women; fixed-effect analysis) (GRADE high). This difference was not evident when we carried out a sensitivity analysis, restricting the analysis to studies at low risk of bias based on study quality (RR 0.75, 95% CI 0.57 to 1.00; one study, 1292 women). There was no difference in the rate of perinatal mortality (RR 1.22, 95% CI 0.86 to 1.72; two studies, 2589 babies) (GRADE low).There was no difference in the number of preterm births at less than 37 weeks (average RR 0.85, CI 0.72 to 1.01; eight studies, 4834 women; random-effects, Tau2 = 0.03, I2 = 68%) (GRADE very low). Infants born to women using home uterine monitoring were less likely to be admitted to neonatal intensive care unit (average RR 0.77, 95% CI 0.62 to 0.96; five studies, 2367 babies; random-effects, Tau2 = 0.02, I2 = 32%) (GRADE moderate). This difference was not maintained when we restricted the analysis to studies at low risk of bias (RR 0.86, 95% CI 0.74 to 1.01; one study, 1292 babies). Women using home uterine monitoring made more unscheduled antenatal visits (mean difference (MD) 0.48, 95% CI 0.31 to 0.64; two studies, 1994 women) (GRADE moderate). Women using home uterine monitoring were also more likely to have prophylactic tocolytic drug therapy (average RR 1.21, 95% CI 1.01 to 1.45; seven studies, 4316 women; random-effects, Tau2 = 0.03, I2 = 62%), but this difference was no longer evident when we restricted the analysis to studies at low risk of bias (average RR 1.22, 95% CI 0.90 to 1.65; three studies, 3749 women; random-effects, Tau2 = 0.05, I2 = 76%) (GRADE low). The number of antenatal hospital admissions did not differ between home groups (RR 0.91, 95% CI 0.74 to 1.11; three studies, 1494 women (GRADE low)). We found no data on maternal anxiety or acceptability.

AUTHORS' CONCLUSIONS

Home uterine monitoring may result in fewer admissions to a neonatal intensive care unit but in more unscheduled antenatal visits and tocolytic treatment; the level of evidence is generally low to moderate. Important group differences were not evident when we undertook sensitivity analysis using only trials at low risk of bias. There is no impact on maternal and perinatal outcomes such as perinatal mortality or incidence of preterm birth.

Vaginal electrohysterography: the design and preliminary evaluation of a novel device for uterine contraction monitoring in an ovine model (.)

OBJECTIVE

Tocodynamometry is the most common method of labor evaluation but most clinicians would agree it has limited utility before 26 weeks of gestation. The obesity epidemic has further reduced our ability to accurately detect uterine contractions using the tocodynamometer at any gestational age. We sought to design and test a novel contraction monitor that bypasses the maternal abdomen.

METHODS

An optimized version of an intravaginal electrohysterographic ring device was tested in an ovine model. The device and its methodology as well as the tocodynamometer were validated against the current gold standard uterine activity monitor, the intrauterine pressure catheter in six sheep at varying gestational ages.

RESULTS

Both the intravaginal ring device and the tocodynamometer correlated well with IUPC, r = 0.69 and 0.73, respectively (p < 0.001). The number of contractions detected by each monitor remained similar even after accounting for confounders.

CONCLUSIONS

These results suggest that uterine activity can be monitored from the vaginal interface in an ovine model and offers an alternative clinical tool for the detection of contractions in situations, in which tocodynamometry would be ineffective or intrauterine monitoring inappropriate.

Home uterine monitoring for detecting preterm labour

BACKGROUND

To reduce the morbidity and mortality associated with preterm birth, home uterine activity monitoring aims for early detection of increased contraction frequency, and early intervention with tocolytic drugs to inhibit labour and prolong pregnancy. However, the effectiveness of such monitoring is disputed.

OBJECTIVES

To determine whether home uterine activity monitoring is effective in improving the outcomes for women and their infants considered to be at high risk of preterm birth, when compared with conventional or other care packages that do not include home uterine monitoring.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2014), CENTRAL (The Cochrane Library 2014, Issue 8), MEDLINE (1966 to 31 August 2014), EMBASE (1974 to 31 August 2014), CINAHL (1982 to 31 August 2014) and scanned reference lists of retrieved studies.

SELECTION CRITERIA

Randomised control trials of home uterine activity monitoring, with or without patient education programmes, for women at risk for preterm birth, in comparison to the same care package without home uterine activity monitoring.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We did not attempt to contact authors to resolve queries.

MAIN RESULTS

There were 15 included studies (total number of enrolled participants 6008); 13 studies contributed data. Women using home uterine monitoring were less likely to experience preterm birth at less than 34 weeks (risk ratio (RR) 0.78; 95% confidence interval (CI) 0.62 to 0.99; three studies, n = 1596; fixed-effect analysis) (GRADE high). The significant difference was not evident when we carried out a sensitivity analysis, restricting the analysis to studies at low risk of bias based on study quality (RR 0.75; 95% CI 0.57 to 1.00, one study, 1292 women). There was no significant difference in the rate of perinatal mortality (RR 1.22; 95% CI 0.86 to 1.72; two studies, n = 2589) (GRADE low)There was no significant difference in the number of preterm births at less than 37 weeks (average RR 0.85; CI 0.72 to 1.01; eight studies, n = 4834; random-effects, T² = 0.03, I² = 68%) (GRADE very low). Infants born to women using home uterine monitoring were less likely to be admitted to neonatal intensive care unit (average RR 0.77; 95% CI 0.62 to 0.96; five studies, n = 2367; random-effects, T² = 0.02, I² = 32%) (GRADE moderate). The difference was not statistically significant when only high quality studies were included (RR 0.86; 95% CI 0.74 to 1.01; one study, n = 1292). Women using home uterine monitoring made more unscheduled antenatal visits (mean difference (MD) 0.49; 95% CI 0.39 to 0.62; two studies, n = 3707) (GRADE moderate). Women using home uterine monitoring were also more likely to have prophylactic tocolytic drug therapy (average RR 1.21; 95% CI 1.01 to 1.45; seven studies, n = 4316; random-effects. T² = 0.03, I² = 62%) but this difference was no longer significant when the analysis was restricted to higher quality studies (average RR 1.22; 95% CI 0.90 to 1.65, three studies, n = 3749,random-effects, T² = 0.05, I² = 76%) (GRADE low). One small study reported that the home uterine monitoring group spent fewer days in hospital antenatally. No data on maternal anxiety or acceptability were found.

AUTHORS' CONCLUSIONS

Home uterine monitoring may result in fewer admissions to a neonatal intensive care unit but more unscheduled antenatal visits and tocolytic treatment, but the level of evidence is generally low to moderate. Important group differences were not evident when sensitivity analysis was undertaken using only high quality trials. There is no impact on maternal and perinatal outcomes such as perinatal mortality or incidence of preterm birth.

Salivary progesterone as a biochemical marker to predict early preterm birth in asymptomatic high-risk women

OBJECTIVE

To evaluate salivary progesterone as a predictor of early preterm birth (PTB) and compare it with transvaginal sonographic (TVS) cervical length in asymptomatic high-risk women.

DESIGN

Prospective study.

SETTING

Departments of Obstetrics and Gynaecology and Biochemistry at UCMS & GTBH, Delhi, India.

SAMPLE

Ninety pregnant women.

METHODS

The progesterone concentration in saliva of asymptomatic pregnant women at high risk for preterm delivery was estimated by immunoassay, and cervical length was measured by TVS, at the first antenatal visit at 24-28 weeks of gestation, and then repeated 3-4 weeks later.

MAIN OUTCOME MEASURES

Early PTB, mean and critical cut-off values of salivary progesterone, and a diagnostic value comparison of salivary progesterone with TVS cervical length.

RESULTS

The mean value of salivary progesterone was significantly lower in all women who delivered at <37 weeks of gestation (n = 38), compared with the term group (n = 52; P < 0.001). Salivary progesterone decreased significantly from the first to the second visit, with the maximum decrease observed in women who delivered at <34 weeks of gestation (29.6%, 95% CI 17.8-41.4%, P < 0.002). The single predictive critical cut-off value for salivary progesterone was 2575 pg/ml, below which more than 80% of women delivered prematurely before 34 weeks of gestation, with sensitivity, specificity, and positive and negative predictive values of 83% (95% CI 58.6-96.4%), 86% (95% CI 75.9-93.1%), 60% (95% CI 38.6-78.8%) and 95% (95% CI 87.1-99.0%), respectively. The TVS cervical length decreased significantly (P < 0.001) in the women who delivered prematurely.

CONCLUSIONS

Low salivary progesterone concentration can be used for predicting early PTB in asymptomatic high-risk women.

Home uterine monitoring for detecting preterm labour

BACKGROUND

To reduce the morbidity and mortality associated with preterm birth, home uterine activity monitoring aims for early detection of increased contraction frequency, and early intervention with tocolytic drugs to inhibit labour and prolong pregnancy. However, the effectiveness of such monitoring is disputed.

OBJECTIVES

To determine whether home uterine activity monitoring is effective in improving the outcomes for women and their infants considered to be at high risk of preterm birth, when compared with conventional or other care packages that do not include home uterine monitoring.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 November 2011), CENTRAL (The Cochrane Library 2011, Issue 4 of 4), MEDLINE (1966 to 30 November 2011), EMBASE (1974 to 30 November 2011), CINAHL (1982 to 30 November 2011) and scanned reference lists of retrieved studies.

SELECTION CRITERIA

Randomised control trials of home uterine activity monitoring, with or without patient education programmes, for women at risk for preterm birth, in comparison to the same care package without home uterine activity monitoring.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data and assessed risk of bias. Data were checked for accuracy. We did not attempt to contact authors to resolve queries.

MAIN RESULTS

There were 15 included studies (total number of enrolled participants 6008); 13 studies contributed data. Women using home uterine monitoring were less likely to experience preterm birth at less than 34 weeks (risk ratio (RR) 0.78; 95% confidence interval (CI) 0.62 to 0.99; three studies, n = 1596; fixed-effect analysis). However, this significant difference was not evident when we carried out a sensitivity analysis, restricting the analysis to studies at low risk of bias based on study quality (RR 0.75; 95% CI 0.57 to 1.00, one study, 1292 women). There was no significant difference in the rate of perinatal mortality (RR 1.22; 95% CI 0.86 to 1.72; two studies, n = 2589).There was no significant difference in the number of preterm births at less than 37 weeks (average RR 0.85; CI 0.72 to 1.01; eight studies, n = 4834; random effects, T(2) = 0.03, I(2) = 68%). Infants born to women using home uterine monitoring were less likely to be admitted to neonatal intensive care unit (average RR 0.77; 95% CI 0.62 to 0.96; five studies, n = 2367; random-effects, T(2) = 0.02, I(2) = 32%). Although this difference was not statistically significant when only high quality studies were included (RR 0.86; 95% CI 0.74 to 1.01; one study, n = 1292). Women using home uterine monitoring made more unscheduled antenatal visits (mean difference (MD) 0.49; 95% CI 0.39 to 0.62; two studies, n = 2807). Women using home uterine monitoring were also more likely to have prophylactic tocolytic drug therapy (average RR 1.21; 95% CI 1.01 to 1.45; seven studies, n = 4316; random-effects. T(2) = 0.03, I(2) = 62%) but this difference was no longer significant when the analysis was restricted to high quality studies (average RR 1.22; 95% CI 0.90 to 1.65, three studies, n = 3749,random effects, T(2) = 0.05, I(2) = 76%). One small study reported that the home uterine monitoring group spent fewer days in hospital antenatally. No data on maternal anxiety or acceptability were found.

AUTHORS' CONCLUSIONS

Home uterine monitoring may result in fewer admissions to a neonatal intensive care unit but more unscheduled antenatal visits and tocolytic treatment. There is no impact on maternal and perinatal outcomes such as perinatal mortality or incidence of preterm birth.

Risk of premature birth in multifetal pregnancy

The risk of preterm delivery ( < 37 weeks of gestation) is approximately nine times higher in women with multifetal pregnancies than in women with singleton pregnancies. However, it is possible that the risk will vary according to gestational week. To assess the risk of premature birth within 1 week by gestational age among multifetal pregnancies and compare the estimated risk with that of singleton pregnancies, we analyzed 6 036 475 infants born in singleton pregnancies and 90 887 infants born in multifetal pregnancies in Japan ( ≥ 22 weeks) over the 5-year period 1989–1993. An estimate of the risk of birth within 1 week at gestational week n was obtained by dividing the number of infants delivered at gestational week n by the number of infants delivered at or beyond gestational week n. The risk at 22 weeks was 0.9 per 1000 fetuses for singleton pregnancies and 5.0 per 1000 for multifetal pregnancies. The risk remained relatively stable until 27 weeks of gestation, then sharply increased toward 36 weeks of gestation in both singleton and multifetal pregnancies. The odds ratio for birth within 1 week for fetuses of multifetal pregnancies compared with fetuses of singleton pregnancies was 5.9 (95% CI, 5.4–6.5) at 22 weeks of gestation, increasing gradually with increasing gestational age until 33 weeks of gestation (13.7; 95% CI, 13.1–14.2) but declining thereafter to 8.8 (95% CI, 8.6–8.9) at 36 weeks of gestation. Results of data analysis for each year of the 5-year period did not differ substantially. Twin Research (2000) 3, 2–6.

Home uterine monitoring: a case of telemedicine failure?

The aim of the article is to explore and explain some of the controversies around home uterine monitoring, using a socio-technical interaction networks (STIN) approach. A Cochrane systematic review identified 15 included studies. A critique of these studies, using the eight components of the STIN framework, illustrated very clearly the different assumptions made about the purpose of home uterine monitoring, and helped to explain the different outcomes. The final mapping stage suggested that systems architecture choices included that of the role of monitoring support, to complement patient education or to enhance education for provider and patient. A similar choice concerned the type and extent of patient-care-provider contacts to be used. Using the STIN framework provided a useful perspective on the telemedicine aspects of home uterine monitoring, providing value beyond the systematic review conclusions alone.

Care for women with prior preterm birth

Women who have delivered an infant between 16 and 36 weeks' gestation have an increased risk of preterm birth in subsequent pregnancies. The risk increases with more than 1 preterm birth and is inversely proportional to the gestational age of the previous preterm birth. African American women have rates of recurrent preterm birth that are nearly twice that of women of other backgrounds. An approximate risk of recurrent preterm birth can be estimated by a comprehensive reproductive history, with emphasis on maternal race, the number and gestational age of prior births, and the sequence of events preceding the index preterm birth. Interventions including smoking cessation, eradication of asymptomatic bacteriuria, progestational agents, and cervical cerclage can reduce the risk of recurrent preterm birth when employed appropriately.

Goals and strategies for prevention of preterm birth: an obstetric perspective

Complications of prematurity surpass congenital malformations as the leading cause of infant mortality in the United States. Since 1990, there has been a steady rise in preterm birth, alarming health professionals from all disciplines. This review from a prenatal perspective confirms those concerns and describes the risks and opportunities that may attend efforts to improve the health of fetuses, newborns, and infants. Fetal and live-born outcomes are included.

Prevention of Preterm Birth

The preterm birth rate in the USA is nearing 13%. The recent rise has been attributed to increased indicated preterm births and multiple births following artificial conceptions. There are few obstetrical interventions that successfully delay or prevent spontaneous preterm birth or reduce the risk factors leading to indicated preterm birth. On the other hand, there are many strategies that have improved outcomes for those infants who are born preterm. These include the use of corticosteroids for fetal maturation and regionalization of perinatal care for high-risk mothers and their infants. Several interventions, including progesterone use and cerclage, demonstrate promise in reducing spontaneous preterm births. The most pressing need is to better define the populations of pregnant women for whom these and other interventions will effectively reduce preterm birth.

South Carolina Partners for Preterm Birth Prevention: a regional perinatal initiative for the reduction of premature birth in a Medicaid population

OBJECTIVE

The objective of the study was to improve the distribution of preterm deliveries in a Medicaid population through a regional perinatal risk assessment and case management initiative.

STUDY DESIGN

An innovative public/private partnership was initiated in the 8 county Lowcountry (LC) perinatal region to reduce preterm birth (PTB) among Medicaid recipient women. Eligible women were identified and underwent telephonic risk assessment, education, and access to a 24 hours, 7 days per week perinatal hotline. Women with predetermined risk factors for PTB were offered patient-centered case management. Medicaid claims and birth certificate data were used to compare obstetric outcomes for 2006 (intervention) and 2004 (control) in both the Lowcountry (LC; program) and Midlands (ML; nonprogram) perinatal regions.

RESULTS

There were 6356 Medicaid deliveries in the LC in 2006. Of these, 2111 were referred for telephonic risk assessment; 317 had identifiable PTB risk factors and consented to case management. Compared with 2004, there was a significant improvement in the distribution of preterm birth (P = .05) in the LC region, primarily confined to deliveries less than 28 weeks (1.6% vs 1.1%; P = .029, relative risk [RR] 0.75, 95% confidence interval [CI], 0.51-0.96). There were also reductions in the frequency (6.7% vs 5.8%; RR 0.86, 95% CI, 0.75-0.98; P = .04) and mean duration (25.0 vs 20.6 days; 95% CI, 1.03-7.77; P = .01) of neonatal intensive care unit (NICU) admissions. No changes were identified in the ML region.

CONCLUSION

A regional initiative of telephonic risk assessment and case management of Medicaid recipient women significantly reduced deliveries less than 28 weeks and NICU care.

Antepartum uterine contraction patterns in twin pregnancies with and without preterm labor and delivering before or after 36 weeks

OBJECTIVE

The purpose of this study was to identify differences in antepartum uterine contraction frequency (UCF) in twin pregnancies with and without preterm labor (PTL).

STUDY DESIGN

Twin gestations enrolled for outpatient surveillance with twice daily electronic uterine activity monitoring and telephonic nursing assessment, without interventional delivery were identified. Mean UCF for each gestational week was compared between women without PTL or preterm delivery (PTD) < 36 weeks (controls) and those with a PTL diagnosis delivering at < 36 weeks (PTL/PTD group), and those with PTL with delivery > or = 36 weeks (PTL/GAD > or = 36 group).

RESULTS

Data from 7891 patients with 267,840 monitored hours were analyzed. UCF at each gestational week was significantly higher for patients experiencing PTL with or without PTD compared to control. UCF was similar for patients with PTL with or without PTD < 36.

CONCLUSION

Twin pregnancies complicated with PTL have a higher UCF than those that do not experience PTL. Outpatient surveillance may be beneficial in this population.

Primary, secondary, and tertiary interventions to reduce the morbidity and mortality of preterm birth

Interventions to reduce the morbidity and mortality of preterm birth can be primary (directed to all women), secondary (aimed at eliminating or reducing existing risk), or tertiary (intended to improve outcomes for preterm infants). Most efforts so far have been tertiary interventions, such as regionalised care, and treatment with antenatal corticosteroids, tocolytic agents, and antibiotics. These measures have reduced perinatal morbidity and mortality, but the incidence of preterm birth is increasing. Advances in primary and secondary care, following strategies used for other complex health problems, such as cervical cancer, will be needed to prevent prematurity-related illness in infants and children.

Physiology and electrical activity of uterine contractions

Presently, there is no effective treatment for preterm labor. The most obvious reason for this anomaly is that there is no objective manner to evaluate the progression of pregnancy through steps leading to labor, either at term or preterm. Several techniques have been adopted to monitor labor, and/or to diagnose labor, but they are either subjective or indirect, and they do not provide an accurate prediction of when labor will occur. With no method to determine preterm labor, treatment might never improve. Uterine electromyography (EMG) methods may provide such needed diagnostics.

Adenomyosis and risk of preterm delivery

OBJECTIVE

To evaluate the risk of preterm delivery in patients with adenomyosis.

DESIGN

A 1:2 nested case-control study.

SETTING

Tertiary-care institution.

POPULATION

A base cohort population of 2138 pregnant women who attended routine prenatal check-up between July 1999 and June 2005.

METHODS

From this base cohort population, gravid women with singleton pregnancy who delivered prior to the completion of 37 weeks of gestation were identified and formed the study group. Singleton gravid women who had term delivery and who matched with age, body mass index, smoking, and status of previous preterm delivery were recruited concurrently and served as control group. Preterm delivery cases were further divided into spontaneous preterm delivery and preterm premature rupture of membranes (PPROM) cases.

MAIN OUTCOME MEASURES

Risk analysis of preterm delivery between gravid women with and without adenomyosis.

RESULTS

One-hundred and four preterm delivery case subjects and 208 control subjects were assessed. Overall, gravid women with adenomyosis were associated with significantly increased risk of preterm delivery (adjusted odds ratio 1.96, 95% CI 1.23-4.47, P=0.022). For subgroup analysis, gravid women with adenomyosis had an adjusted 1.84-fold risk of spontaneous preterm delivery (95% CI 1.32-4.31, P=0.012) and an adjusted 1.98-fold risk of PPROM (95% CI 1.39-3.15, P=0.017).

CONCLUSIONS

Gravid women with adenomyosis were associated with increased risk of both spontaneous preterm delivery and PPROM. A common pathophysiological pathway may exist in these two disorders. Further in-depth biochemical and molecular studies are necessary to explore this phenomenon.

Low birth weight in the United States

Pregnancy outcomes in the United States and other developed countries are considerably better than those in many developing countries. However, adverse pregnancy outcomes are generally more common in the United States than in other developed countries. Low-birth-weight infants, born after a preterm birth or secondary to intrauterine growth restriction, account for much of the increased morbidity, mortality, and cost. Wide disparities exist in both preterm birth and growth restriction among different population groups. Poor and black women, for example, have twice the preterm birth rate and higher rates of growth restriction than do most other women. Low birth weight in general is thought to place the infant at greater risk of later adult chronic medical conditions, such as diabetes, hypertension, and heart disease. Of interest, maternal thinness is a strong predictor of both preterm birth and fetal growth restriction. However, in the United States, several nutritional interventions, including high-protein diets, caloric supplementation, calcium and iron supplementation, and various other vitamin and mineral supplementations, have not generally reduced preterm birth or growth restriction. Bacterial intrauterine infections play an important role in the etiology of the earliest preterm births, but, at least to date, antibiotic treatment either before labor for risk factors such as bacterial vaginosis or during preterm labor have not consistently reduced the preterm birth rate. Most interventions have failed to reduce preterm birth or growth restriction. The substantial improvement in newborn survival in the United States over the past several decades is mostly due to better access to improved neonatal care for low-birth-weight infants.

The impact of multiple gestations on late preterm (near-term) births

Multiple pregnancies currently account for 3% of all births in the United States but are disproportionately responsible for larger rates of prematurity and significant neonatal morbidity. The mean birth age for most multi-fetal pregnancies occurs during the late preterm period when both spontaneous preterm labor and iatrogenic premature birth because of obstetrical or maternal complications are common. Multiples pose numerous unique challenges, emphasizing the significant impact of plurality on late preterm births.

Deciding When It's Labor: The Experience of Women Who Have Received Antepartum Care at Home for Preterm Labor

OBJECTIVE

To describe how women who had received antepartum care at home for preterm labor managed subsequent episodes of preterm labor symptoms.

DESIGN

Grounded theory method.

SETTING

2 Canadian antepartum home care programs.

PARTICIPANTS

12 women who received antepartum care at home for preterm labor that had been diagnosed in hospital prior to 34 weeks gestation.

RESULTS

The core psychosocial process was reconciling body knowledge and professional knowledge. Study participants reported knowing something's not right and followed decision guides to seek help. If, when they returned to the hospital to see what's going on, they felt dissonance between what their bodies were telling them (body knowledge) and what their health care providers were telling them (professional knowledge) an overriding tension developed between not wanting to take a risk for the baby versus not wanting to overreact. These women reestablished their baselines of nonthreatening symptoms at a higher level by setting a new normal to avoid the humiliation associated with appearing to overreact. Attempting to ignore recurring symptoms of preterm labor delayed help seeking and caused anxiety.

CONCLUSIONS

To avoid delayed help seeking, nursing interventions should be geared to reducing anxiety and validating the experiences of women with recurring preterm labor symptoms.

Predictors of preterm birth

OBJECTIVE

This is a systematic review to assess published scientific evidence on preterm birth predictors.

METHODS

An Internet search for predictors of preterm birth was performed and the evidence level of each method was evaluated.

RESULTS

There is strong evidence that preterm birth can be predicted using vaginal sonography to evaluate cervical characteristics, fetal fibronectin in cervicovaginal secretions and interleukin-6 in amniotic fluid. There is consistent evidence that digital cervical examination is a weak predictor, and controversy regarding home uterine activity monitoring. There is scanty evidence about the predictive ability of maternal history and perceptions of symptoms since the study design fails to provide high evidence level.

CONCLUSION

Cervical evaluation by vaginal sonography, fetal fibronectin and interleukin-6 are the best methods for predicting preterm birth.

Multiple gestations and late preterm (near-term) deliveries

Multiple gestations present unique challenges to the modern obstetrician. Many twin and high-order multiple pregnancies are delivered between 34 and 37 weeks' gestation either secondary to preterm labor or obstetrical complications necessitating intervention. Recognizing the increasing prevalence of multiple gestations and the impact of late preterm deliveries in modern practice, this review analyzes the impact of multiple pregnancies on perinatal outcomes, reviews the strategies to prevent preterm labor, and summarizes potential indications for late preterm delivery. In this paper, "late preterm" has been used instead of "near-term," as the former was considered more appropriate to reflect this subgroup of preterm infants in a workshop on this topic held in July 2005, organized by the National Institute of Child Health and Human Development.

Uterine contraction assessment

Few approaches to preterm birth prevention have been as thoroughly studied yet as enigmatic as uterine contraction assessment. Despite multiple randomized clinical trials (level 1 evidence), the effectiveness of home uterine contraction assessment as an adjunct to the clinical management of women at risk for preterm birth remains controversial. This article reviews these trials with particular attention to study design and patient inclusion criteria. The data are absolutely clear that home uterine contraction monitoring with or without frequent perinatal nursing contact can reduce the risk of preterm birth and improve perinatal outcomes and that both are independently superior to standard preterm birth prevention education and care.

Maternal physiology and complications of multiple pregnancy

Approximately 1% to 3% of all pregnancies in the United States are multiple gestations. The vast majority (97-98%) are twin pregnancies. Multiple pregnancies constitute significant risk to both mother and fetuses. Antepartum complications-including preterm labor, preterm premature rupture of the membranes, intrauterine growth restriction, intrauterine fetal demise, gestational diabetes, and preeclampsia-develop in over 80% of multiple pregnancies as compared with approximately 25% of singleton gestations. This article reviews in detail the maternal physiologic adaptations required to support a multiple pregnancy and the maternal complications that develop when these systems fail or are overwhelmed.

Use of uterine EMG and cervical LIF in monitoring pregnant patients

OBJECTIVES

Review the uterine electromyography (EMG) and cervical light-induced fluorescence (LIF) devices and their role in the evaluation of uterine and cervical function in comparison with present methods.

DESIGN

Review of recent studies.

SETTING

University of Texas Medical Branch Labour and Delivery Clinics.

POPULATION

Various groups of pregnant women.

METHODS

We have developed and recently improved non-invasive methods to evaluate quantitatively uterine electrical signals from the abdominal surface and cervical collagen.

MAIN OUTCOME MEASURES

Uterine EMG utilised power density spectrum (PDS) peak frequency and total power (P(0)) and cervical LIF utilising LIF ratio.

RESULTS

Human studies indicate that uterine and cervical performance can be successfully monitored during pregnancy using EMG and LIF, respectively, and the assessment of uterine and cervical function can both be used to influence patient management in a variety of conditions associated with labour, more than can currently available methods.

CONCLUSIONS

The potential benefits of the proposed instrumentation include the following: a reduction in the rate of preterm birth, improved maternal and perinatal outcome, better monitoring of treatment, decreased caesarean section rate and better research methods for understanding uterine and cervical function.

APN-physician collaboration in caring for women with high-risk pregnancies

PURPOSE

To examine: (a) frequency and focus of APN-physician collaborations in a clinical trial in which half of physician prenatal care for women with high-risk pregnancies was substituted with APN prenatal care delivered in women's homes; and (b) characteristics of women requiring greater numbers of collaborations.

DESIGN AND METHODS

Descriptive study with secondary analysis of data from 83 of the original trial's 85 intervention participants followed by APNs prenatally through 8 weeks postpartum. APN practices, recorded in logs, included APN interactions with the women and the physician, and type of APN contact (e.g., home visit, telephone call). Each APN-physician collaboration was coded for type, timing, and focus.

FINDINGS

Total number of APN-physician collaboration contacts was 351, with a mean of 4.5 and a range of 1 to 16 per woman. Focus of collaborations was: status updates (59%), new physical findings (21%), change in treatment (8%), patient concerns (7%) and medication adjustment (5%). No significant differences in numbers of collaborations were found according to age, primary diagnosis, marital status, type of health insurance, race, or income. Women with high school education received more collaborations than did those not completing high school or those with some postsecondary education. Prenatally, women with a first pregnancy required more collaborations than did multipara participants.

CONCLUSIONS

Most APN-physician collaborative contacts were focused on monitoring women's physical and emotional status and discussing new physical findings. These collaborations were important in the original trial's successful pregnancy and infant outcomes and savings in health care dollars.

The changing association between prenatal participation in WIC and birth outcomes in New York City

We analyze the relationship between prenatal WIC participation and birth outcomes in New York City from 1988-2001. The analysis is unique for several reasons. First, we have over 800,000 births to women on Medicaid, the largest sample ever used to analyze prenatal participation in WIC. Second, we focus on measures of fetal growth distinct from preterm birth, since there is little clinical support for a link between nutritional supplementation and premature delivery. Third, we restrict the primary analysis to women on Medicaid who have no previous live births and who initiate prenatal care within the first four months of pregnancy. Our goal is to lessen heterogeneity between WIC and non-WIC participants by limiting the sample to highly motivated women who have no experience with WIC from a previous pregnancy. Fourth, we analyze a large sub-sample of twin deliveries. Multifetal pregnancies increase the risk of anemia and fetal growth retardation and thus may benefit more than singletons from nutritional supplementation. We find no relationship between prenatal WIC participation and measures of fetal growth among singletons. We find a modest pattern of association between WIC and fetal growth among U.S.-born Black twins. Our findings suggest that prenatal participation in WIC has had a minimal effect on adverse birth outcomes in New York City.

Towards improved neonatal outcome: future strategies

The role of the obstetrician is to help predict and prevent maternal/fetal infection/inflammation related to neonatal mortality and morbidity. Predictive studies have mainly focused on the high-risk phenotype. Currently, there is a scientific drive to analyse the genetic susceptibility of preterm birth (PTB). Studies of the combination of environmental and lifestyle risk factors with the known genotype may result in a better understanding of the causation of PTB. Predictive technical markers such as fibronectin, cervical length measurement and home uterine activity remain largely unproven. Current antenatal care has not achieved primary prevention of PTB. Tocolytics and antibiotics constitute the two key elements of secondary prevention. Tocolytics have a minimal benefit but should not be used to prolong an infected preterm pregnancy. The use of antibiotics in preterm premature rupture of membranes can prolong the pregnancy with a decrease in neonatal morbidity. Anti-inflammatory cytokines, cytokine inhibitors and soluble cytokine receptors are promising treatment options that could modulate the intra-amniotic inflammatory process.

Preterm deliveries among women with MacDonald cerclage performed due to cervical incompetence

OBJECTIVE

The study was aimed to assess the impact of obstetric risk factors for preterm delivery among women with MacDonald cerclage performed due to cervical incompetence.

STUDY DESIGN

A cohort study was conducted including all patients with MacDonald cerclage performed at 12-14 weeks gestation due to cervical incompetence (n = 793). Deliveries occurred between the years 1988 and 2002 in a University Medical Center. A multiple linear regression model was used to assess the impact of maternal characteristics as well as pregnancy complications on the length of pregnancy.

RESULTS

The following factors were found to be associated with preterm delivery among these patients, in the univariate analysis: nulliparity, fertility treatments, severe preeclampsia, second-trimester bleeding, premature rupture of membranes (PROM), chorioamnionitis and placental abruption. Using a multiple linear regression model, with backward elimination, the impact of these variables on the length of pregnancy was assessed (R(2) = 0.33, p < 0.001). The mean gestational age at birth among patients without risk factors was 38.1. Second-trimester bleeding reduced gestational age by 6.4 weeks, chorioamnionitis by 5.6 weeks, placental abruption by 5.1 weeks, PROM by 3.2 weeks and severe preeclampsia by 2.4 weeks.

CONCLUSIONS

Second-trimester bleeding, chorioamnionitis, placental abruption, PROM and severe preeclampsia are ominous signs for preterm delivery among patients with MacDonald cerclage performed due to cervical incompetence.

Current status of home uterine activity monitoring

A comprehensive evidence-based review of the clinical data leads to the conclusion that if patients at high risk for preterm birth (eg, prior preterm birth because of preterm labor, twins and higher-order multiple gestation, women who have preterm labor during the current pregnancy tocolyzed effectively) use the comprehensive system of HUAM correctly (ie, daily nursing care and twice-daily monitoring) with appropriate alarm rates and sensitive monitors, the incidence of early diagnosis of preterm labor, effective prolongation of pregnancy with fewer preterm births, and a reduction in neonatal morbidity is always demonstrated when the study group is compared with a control group consisting of women receiving standard care available to obstetricians in the United States. The authors expect that there will always be arguments regarding whether the monitor or the nurse contributes most to preterm birth reduction. Even when the alerts of detected contractions or patient-reported symptoms are sounded, the issue of prompt and effective medical intervention will always be hotly debated. The appropriate research design that tests HUAM while allowing various diagnostic and treatment modalities that physicians employ around the United States must be individualized. Physicians must make the decision, based on the evidence, regarding whether or not this system would benefit their patients. While investigators argue about research designs and statistical analyses, physicians simply want the best outcomes for their patients, which is what women and the whole of society also want. Based on the available evidence, it is clear that when the comprehensive system of HUAM is used appropriately in the right patients, everyone benefits.

The physiology of uterine contractions

Studies in animals and humans indicate that uterine performance can be successfully monitored during pregnancy using uterine electromyography. Uterine electromyography could be used to better define management in a variety of conditions associated with human labor. The potential benefits of the proposed instrumentation and method include: reducing the rate of preterm delivery, improving maternal and perinatal outcome, monitoring treatment, decreasing cesarean-section rate, and providing research methods to better understand uterine function.

Our unrequited love for simple explanation

In the complex and often perplexing field of perinatology, it is often tempting to extrapolate the results of the latest published study to our daily clinical practice, especially when the study appears to provide simple answers to difficult questions. This tendency is further encouraged by sensational media coverage and commentaries that, by necessity, further simplify the issues and hype the speculation. Without a critical appraisal of the study population, methodology, analysis and conclusions stated, globalizing a single study's results to anyone's clinical practice can be well-intentioned but misguided. As an example, approximately 1 year ago the results of an NICHD study involving home uterine activity monitoring (HUAM) were released. The study concluded that, while the likelihood of preterm delivery increased with an increased baseline frequency of uterine contractions, measurement of this contractility was not a clinically efficient predictor of preterm delivery. Through the media and editorials that followed, the study results became translated so as to indicate that HUAM was not effective in preventing preterm delivery or improving perinatal outcomes. In our desire for a simple and definitive conclusion on HUAM, key facts about this study were forgotten. In the NICHD study, uterine contraction data were blinded to both physician and patient, and only intermittent preterm monitoring was used with no provision for emergency monitoring; a study design that guaranteed patient management and outcomes would not be affected by HUAM. Using the NICHD HUAM study as an example to be learned from, we should be more critical and independent in our appraisal of published trials. Evidence-based medicine is only useful when we pay as much attention to the methodology as we do to the results.

Preventing low birth weight: is prenatal care the answer?

OBJECTIVES

To review the evidence of effectiveness of prenatal care for preventing low birth weight (LBW).

METHODS

We reviewed original research, systematic reviews, meta-analyses and commentaries for evidence of effectiveness of the three core components of prenatal care--risk assessment, health promotion and medical and psychosocial interventions--for preventing the two constituents of LBW: preterm birth and intrauterine growth restriction (IUGR).

RESULTS

Clinical risk assessment will fail to identify the majority of pregnancies at risk for preterm delivery or IUGR. While biophysical and biochemical modalities appear promising, their cost-effectiveness has not been demonstrated, nor can their routine use be recommended in the absence of effective interventions. Smoking cessation programs appear to be modestly effective. There is insufficient evidence to conclude a benefit for nutrition interventions, work counseling or preterm birth education. Only antenatal corticosteroid therapy has demonstrated a clear benefit in the tertiary prevention of preterm delivery. Interventions for which there is insufficient evidence to conclude a benefit include bed rest, hydration, sedation, cerclage, progesterone supplementation, antibiotic treatment, tocolysis without concomitant use of corticosteroids, thyrotropin-releasing hormone, psychosocial support and home visitation. Additionally, there is a paucity of evidence supporting the effectiveness of prenatal interventions, such as low-dose aspirin, bed rest, maternal hyperoxygenation, plasma volume expansion and antenatal fetal assessment, in preventing IUGR or its associated morbidity and mortality.

CONCLUSIONS

Neither preterm birth nor IUGR can be effectively prevented by prenatal care in its present form. Preventing LBW will require reconceptualization of prenatal care as part of a longitudinally and contextually integrated strategy to promote optimal development of women's reproductive health not only during pregnancy, but over the life course.

What have we learned about uterine contractions and preterm birth? The HUAM Prediction Study

Measurement of uterine contraction frequency has been employed as a screening test to identify women with increased risk of preterm birth, and as an aid in the early diagnosis of preterm labor. The National Institute of Child Health and Human Development Maternal-Fetal Medicine Units (NICHD MFMU) Network performed a prospective, blinded observational study of uterine contraction frequency to detect and predict preterm labor and birth, respectively. The goal of the study was to assess the sensitivity, specificity, and positive and negative predictive value of various measures of uterine contraction frequency. Data collected from 306 women revealed that contraction frequency was significantly greater in women who would ultimately deliver before rather than after 35 weeks' gestation. However, both sensitivity and positive predictive value of any measure of contraction frequency to predict preterm birth were poor. Contraction frequency did not increase significantly within 1 or 2 weeks of an episode of preterm labor. These results serve to explain the absence of an association between contraction-based surveillance and preterm birth in randomized trials conducted in women at risk of preterm birth.

Vaginal sonography and cervical incompetence

Uterine contractions, decidual activation, and cervical competence comprise the fundamental components in contemporary models of the spontaneous preterm birth syndrome, but their relative importance and interactive pathways remain poorly defined. Moreover, the traditional concept that the cervix is either competent or incompetent has been challenged because cervical competence more likely functions along a biologic continuum. Cervical incompetence is a clinical diagnosis characterized by recurrent painless dilation and spontaneous midtrimester birth. Although the efficacy of cerclage for cervical incompetence has never been fully confirmed in randomized clinical trials, the role of cerclage has been expanded to include women with "risk factors" for spontaneous preterm birth or nonreassuring sonographic cervical findings in the mid trimester. Evidence from randomized trials suggests that cerclage has limited efficacy in women with risk factors for cervical incompetence. Results of both retrospective cohort series and randomized trials of cerclage in women with shortened cervical length are inconclusive. We believe that women with a prior early spontaneous preterm birth and shortened midtrimester cervical length represent an ideal population for the conduct of a randomized trial of cerclage, which is currently underway.

Implementing preterm labor guidelines: a collaborative care improvement process

Health care organizations today are being challenged to deliver care that is cost-effective, satisfying to patients, and based on quality outcomes. Urgency created by inadequate bed capacity as well as financial opportunity prompted United Hospital's Birth Center to launch care improvement activities aimed at assessing appropriateness of antepartal length of stay. Collaboration between all members of the health care team enabled a steering committee to implement evidence-based provider practice guidelines targeting variance around preterm labor management. Other multidisciplinary strategies implemented include a home care prescreening process, case management, and establishment of a peer review process. Within the 1-year care improvement process, the Birth Center successfully decreased the length of stay for preterm labor patients from 6.9 days to 5.3 days. This article describes one institution's efforts to improve care by implementing guidelines for the inpatient management of preterm labor.