Placental alpha microglobulin-1 (PartoSure) test for the prediction of preterm birth: a systematic review and meta-analysis

Knowledge mapping for prediction of spontaneous preterm birth

INTRODUCTION

Preterm birth (PTB) before 37 weeks gestation, especially spontaneous premature birth (sPTB), poses significant global health challenges, with rising rates linked to advanced and multiple pregnancies. Despite efforts to understand the pathogenesis and related biomarkers of sPTB, accurate prediction is still difficult to achieve. Recent research in academic journals has focused on sPTB prediction, prompting our bibliometric analysis to understand the current situation and explore the new research direction.

METHODS

We used keywords in the Web of Science Core Collection (WoSCC) to search for articles related to sPTB prediction from 2004 to 2023. Subsequently, we primarily employed three distinct software tools (VOSviewer, CiteSpace, and Python) for conducting this bibliometric analysis.

RESULTS

Focusing on sPTB as the primary subject, a total of 647 papers have been published in 136 academic journals. There are the most publications from The United States (n = 245, 39.26 %), and the University of London contributed the most publications (n = 57, 8.81 %). The American Journal of Obstetrics and Gynecology is the most productive academic journal on sPTB prediction [n = 74, 11.44 %; impact factor (IF) = 8.7]. Through the co-occurrence and cluster analysis, we found that recent research has focused on is "pamg-1", "uterocervical angle", "twin pregnancy", "quantitative ultrasound", and "lactobacillus iners".

CONCLUSION

We utilized bibliometric software to perform a comprehensive analysis of the literature concerning sPTB prediction. Broadly, the primary focus of future sPTB prediction lies in the application of novel ultrasound and biological markers, as well as in predicting sPTB in twin pregnancies.

sCEACAM-1 levels in maternal blood in case of threatened preterm birth

INTRODUCTION

This study aims to investigate the role of CEACAM1 in preterm birth. Preterm birth is a phenomenon with numerous triggers, with the immune system hypothesized to play a significant role in the process, aligning with the concept of 'birth as an immunological rejection phenomenon'. There are several approaches to predict preterm birth, and the determination of sCEACAM1 levels, a member of the carcinoembryonic antigen family, may serve as a potential candidate biomarker.

METHODS

A single-center prospective case series study included 67 pregnant women aged 18 years or older who presented before 37 weeks of gestation with signs of preterm birth in the years 2021-2023. At the time of admission, CEACAM1 was determined in maternal blood.

RESULTS

The median sCEACAM1 levels were significantly higher in women who delivered preterm compared to those who delivered at term respectively, 5014 pg/ml (IQR: 3592-8826) vs. 3353 pg/ml (IQR: 2354-5049) (p = 0.016). The median sCEACAM1 level in the group with PPROM (premature preterm rupture of membranes) at 34 weeks' gestation was 7001 pg/ml (IQR: 5683-13509), while the median sCEACAM1 level in the group without PPROM at 34 weeks' gestation was 3884 pg/ml (IQR; 2461-4985) (p < 0.001).

CONCLUSIONS

Pregnant women with preterm birth and/or PPROM before 34 weeks' gestation have higher CEACAM1 levels compared to women with threatened preterm labor who finally had labot at term. The results suggest early activated immune system as a potential pathomechanism of preterm delivery.

Assessment of current biomarkers and interventions to identify and treat women at risk of preterm birth

Preterm birth remains an important global problem, and an important contributor to under-5 mortality. Reducing spontaneous preterm birth rates at the global level will require the early identification of patients at risk of preterm delivery in order to allow the initiation of appropriate prophylactic management strategies. Ideally these strategies target the underlying pathophysiologic causes of preterm labor. Prevention, however, becomes problematic as the causes of preterm birth are multifactorial and vary by gestational age, ethnicity, and social context. Unfortunately, current screening and diagnostic tests are non-specific, with only moderate clinical risk prediction, relying on the detection of downstream markers of the common end-stage pathway rather than identifying upstream pathway-specific pathophysiology that would help the provider initiate targeted interventions. As a result, the available management options (including cervical cerclage and vaginal progesterone) are used empirically with, at best, ambiguous results in clinical trials. Furthermore, the available screening tests have only modest clinical risk prediction, and fail to identify most patients who will have a preterm birth. Clearly defining preterm birth phenotypes and the biologic pathways leading to preterm birth is key to providing targeted, biomolecular pathway-specific interventions, ideally initiated in early pregnancy Pathway specific biomarker discovery, together with management strategies based on early, mid-, and-late trimester specific markers is integral to this process, which must be addressed in a systematic way through rigorously planned biomarker trials.

Trends in antenatal corticosteroid administration: did our timing improve?

OBJECTIVES

We aimed to analyze trends in the rate of effective antenatal corticosteroid prophylaxis (ACS) administrations across a spectrum of typical diagnoses associated with preterm birth.

METHODS

In this retrospective study we utilized delivery data after ACS from 2014 to 2020 at Charité Berlin, Germany. We evaluated the rate of effective ACS administrations defined as ≤10 days between last dose of ACS and delivery as well as the rate of post-ACS births on/after 37 + 0 weeks. We explored conditions associated with high rates of ineffective ACS administrations (>10 days before delivery). We analyzed the trend of ACS-effectiveness during the study period in the overall cohort and in placental dysfunction and cervical insufficiency diagnoses.

RESULTS

The overall rate of effective ACS administrations was 42 % (709/1,672). The overall percentage of deliveries after/at 37 + 0 weeks following ACS administration was 19 % (343). Placenta previa, twin pregnancy and isthmocervical insufficiency were associated with ineffective ACS (19-34 % effective i.e. ≤10 days before delivery). The overall ratio of effective ACS applications rose over time (p=0.002). Over the course of this study ACS effectiveness increased in placental dysfunction and isthmocervical insufficiency diagnoses (p=0.028; p=0.001).

CONCLUSIONS

Compared to a previous publication we found a decrease of post-ACS deliveries after/at 37 + 0 weeks (19 vs. 27 %). Ineffective ACS administrations are still frequent in patients with placenta previa, twin pregnancy and isthmocervical insufficiency. It remains to be investigated in future trials if the introduction of new diagnostic tools such as soluble Fms-like tyrosinkinase-1/placental growth factor (sFlt-1/PlGF) testing and placental alpha-microglobulin-1 (PAMG-1) testing directly led to an increased ACS effectiveness.

Timing of antenatal corticosteroids and survival without neurologic disabilities at 5½ years in children born before 35 weeks of gestation

BACKGROUND

The efficacy of antenatal corticosteroids for neonatal preterm complications wanes beyond 7 days after treatment. The neurodevelopmental effects of longer treatment-to-birth intervals have not been adequately evaluated.

OBJECTIVE

This study aimed to assess the impact of antenatal corticosteroid timing on survival without moderate or severe neurologic disabilities at 5½ years.

STUDY DESIGN

This was a secondary analysis of the EPIPAGE-2 study, a national population-based cohort (France) that recruited neonates in 2011 and followed them up at 5½ years (results first reported in 2021). Participants were children born alive between 24+0 and 34+6 weeks, with a complete corticosteroid course, delivery >48 hours after the first injection, and neither limitation of care decided before birth nor severe congenital malformation. The study included 2613 children, 2427 of whom were alive at 5½ years; 71.9% (1739/2427) had a neurologic assessment at this age; 1537 had a clinical examination (complete for 1532), and 202 were assessed with a postal questionnaire. Exposure was defined as the interval between the first injection of the last antenatal corticosteroid course and delivery in days, studied in 2 categories (days 3-7 and after day 7), in 4 categories (days 3-7, 8-14, 15-21, and after day 21), and continuously in days. The main outcome was survival at 5½ years without moderate/severe neurologic disabilities, defined as moderate/severe cerebral palsy, or unilateral or bilateral blindness or deafness, or Full-Scale Intelligence Quotient 2 standard deviations below the mean. A multivariate analysis with a generalized estimated equation logistic regression model assessed the statistical association between the main outcomes and the interval from the first corticosteroid injection of the last course to birth. Multivariate analyses were adjusted for potential confounders, defined with a directed acyclic graph: gestational age in days, number of corticosteroid courses, multiple pregnancy, and cause of prematurity in 5 categories. Because neurologic follow-up was complete in only 63.2% of cases (1532/2427), the analyses used imputed data.

RESULTS

Among 2613 children, 186 died between birth and 5½ years. Overall survival was 96.6% (95% confidence interval, 95.9-97.0), and survival without moderate or severe neurologic disabilities was 86.0% (95% confidence interval, 84.7-87.0). Survival without moderate or severe neurologic disabilities was lower after day 7 (85.0%) than during the interval from day 3 to day 7 (87.0%) (adjusted odds ratio, 0.70; 95% confidence interval, 0.54-0.89).

CONCLUSION

The association of a >7-day interval between antenatal corticosteroid administration and birth with a lower rate of survival without moderate or severe neurologic disabilities among children aged 5½ years emphasizes the importance of better targeting women at risk of preterm delivery to optimize the timing and thus benefits of treatment.

Further Evidence that an Episode of Premature Labor Is a Pathologic State: Involvement of the Insulin-Like Growth Factor System

INTRODUCTION

Approximately 47% of women with an episode of preterm labor deliver at term; however, their infants are at greater risk of being small for gestational age and for neurodevelopmental disorders. In these cases, a pathologic insult may disrupt the homeostatic responses sustaining pregnancy. We tested the hypothesis of an involvement of components of the insulin-like growth factor (IGF) system.

METHODS

This is a cross-sectional study in which maternal plasma concentrations of pregnancy-associated plasma protease (PAPP)-A, PAPP-A2, insulin-like growth factor-binding protein 1 (IGFBP-1), and IGFBP-4 were determined in the following groups of women: (1) no episodes of preterm labor, term delivery (controls, n = 100); (2) episode of preterm labor, term delivery (n = 50); (3) episode of preterm labor, preterm delivery (n = 100); (4) pregnant women at term not in labor (n = 61); and (5) pregnant women at term in labor (n = 61). Pairwise differences in maternal plasma concentrations of PAPP-A, PAPP-A2, IGFBP-1, and IGFBP-4 among study groups were assessed by fitting linear models on log-transformed data and included adjustment for relevant covariates. Significance of the group coefficient in the linear models was assessed via t-scores, with p < 0.05 deemed a significant result.

RESULTS

Compared to controls, (1) women with an episode of premature labor, regardless of a preterm or a term delivery, had higher mean plasma concentrations of PAPP-A2 and IGFBP-1 (each p < 0.05); (2) women with an episode of premature labor who delivered at term also had a higher mean concentration of PAPP-A (p < 0.05); and (3) acute histologic chorioamnionitis and spontaneous labor at term were not associated with significant changes in these analytes.

CONCLUSION

An episode of preterm labor involves the IGF system, supporting the view that the premature activation of parturition is a pathologic state, even in those women who delivered at term.

Preterm Birth and Corticotrophin-Releasing Hormone as a Placental Clock

Preterm birth worldwide remains a significant cause of neonatal morbidity and mortality, yet the exact mechanisms of preterm parturition remain unclear. Preterm birth is not a single condition, but rather a syndrome with a multifactorial etiology. This multifactorial nature explains why individual predictive measures for preterm birth have had limited sensitivity and specificity. One proposed pathway for preterm birth is via placentally synthesized corticotrophin-releasing hormone (CRH). CRH is a peptide hormone that increases exponentially in pregnancy and has been implicated in preterm birth because of its endocrine, autocrine, and paracrine roles. CRH has actions that increase placental production of estriol and of the transcription factor nuclear factor-κB, that likely play a key role in activating the myometrium. CRH has been proposed as part of a placental clock, with early activation of placental production resulting in preterm birth. This article will review the current understanding of preterm birth, CRH as an initiator of human parturition, and the evidence regarding the use of CRH in the prediction of preterm birth.

Prediction and prevention of preterm birth in pregnant women living with HIV on antiretroviral therapy

INTRODUCTION

The rate of spontaneous preterm-birth among pregnant women living with HIV on antiretroviral therapy (ART) is 3- to 4-fold higher when compared to HIV-negative women. The pathophysiology of preterm-birth related to HIV or ART remains unknown, especially as women living with HIV are often excluded from preterm birth studies.

AREAS COVERED

This review discusses the currently available evidence on the prediction and prevention of preterm-birth in pregnant women living with HIV. A review of the literature was conducted of primary articles between 2005 and 2021 measuring the association or lack thereof between combination ART and preterm birth, as well as of other predisposing factors to preterm birth in women living with HIV, including cervical length, vaginal microbiome, and cervico-vaginal biomarkers.

EXPERT OPINION

Further research into the effect of ART exposure on preterm-birth risk is critical, and development of preterm-birth predictive tools in this population should be a priority. Vaginal progesterone supplementation deserves further investigation as a therapeutic option to prevent recurrent preterm birth in pregnant women living with HIV. The ProSPAR study, a multicenter randomized controlled trial studying progesterone supplementation in pregnant women on protease inhibitor-based regimens, has been designed but is not yet recruiting patients.

Current Resources for Evidence-Based Practice, January 2022

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes a discussion of breastfeeding while employed and commentaries on reviews focused on mammography test characteristics and sexual health for gynecologic cancer survivors. It also includes a quick update on a USPSTF review for aspirin as pre-eclampsia prophylaxis.

Prediction of Spontaneous Preterm Birth in At-risk Women Using Thrombospondin 1 from Cervicovaginal Fluid: A Prospective Observational Study

Introduction Thrombospondin 1, desmoplakin and stratifin are putative biomarkers for the prediction of preterm birth. This study aimed to validate the predictive capability of these biomarkers in patients at risk of preterm birth.

Materials and Methods We included 109 women with symptoms of threatened spontaneous preterm birth between weeks 20 0/7 and 31 6/7 of gestation. Inclusion criteria were uterine contractions, cervical length of less than 25 mm, or a personal history of spontaneous preterm birth. Multiple gestations were also included. Samples of cervicovaginal fluid were taken before performing a digital examination and transvaginal ultrasound. Levels of cervicovaginal thrombospondin 1, desmoplakin and stratifin were quantified by enzyme-linked immunosorbent assays. The primary endpoint was spontaneous preterm birth before 34 + 0 weeks of gestation.

Results Sixteen women (14.7%) delivered before 34 + 0 weeks. Median levels of thrombospondin 1 were higher in samples where birth occurred before 34 weeks vs. ≥ 34 weeks of gestation (4904 vs. 469 pg/mL, p < 0.001). Receiver operator characteristics analysis resulted in an area under the curve of 0.86 (p < 0.0001). At an optimal cut-off value of 2163 pg/mL, sensitivity, specificity, positive predictive value and negative predictive value were 0.94, 0.77, 0.42 and 0.99, respectively, with an adjusted odds ratio of 32.9 (95% CI: 3.1 – 345, p = 0.004). Multiple gestation, cervical length, and preterm labor had no impact on the results. Survival analysis revealed a predictive period of more than eight weeks. Levels of desmoplakin and stratifin did not differ between groups.

Conclusion Thrombospondin 1 allowed long-term risk estimation of spontaneous preterm birth.

Placental α-microglobulin-1 in cervicovaginal fluid and cervical length to predict preterm birth by Thai women with symptoms of labor

Background

Presence of placental α microglobulin-1 (PAMG-1) in cervicovaginal fluid is a bedside test to predict preterm delivery.

Objective

To determine whether the accuracy of a positive PAMG-1 test result to predict preterm birth within 7 days and 14 days in our hospital setting can be improved by adding cervical length.

Methods

We recruited 180 pregnant women who attended the labor ward of Siriraj Hospital, Thailand, from 2016 to 2018 for this prospective observational study of diagnostic accuracy. We used data from 161 women who met inclusion criteria including symptoms of preterm labor between 200/7 and 366/7 weeks' gestation without ruptured membranes and with cervical dilatation <3 cm and effacement <80%. Presence of PAMG-1 in cervicovaginal fluid was tested using a PartoSure kit, cervical length was measured by transvaginal ultrasound, and the time to spontaneous delivery was calculated.

Results

Pregnant women with labor pain who had cervical length <30 mm (45/161; 28%) went into delivery within 7 days, and women with a cervical length <15 mm (11/14; 79%) went into delivery within 7 days. When the PAMG-1 test result was positive and cervical length was ≤15 mm, the positive predictive value (PPV) was 83%; and when cervical length was ≤30 mm the PPV was 69%. The optimal cut off from receiver operating characteristic curve analysis showed that a cervical length <25 mm and PAMG-1 positive result has a PPV of 80% to predict preterm birth within 7 days and 90% within 14 days. The area under the curve (95% confidence interval) for a positive PAMG-1 result and cervical length ≤25 mm to predict preterm birth <7 days was 0.61 (0.50, 0.73) and <14 days was 0.60 (0.49, 0.70).

Conclusions

Cervical length ranging 15-30 mm combined with a positive PAMG-1 test result has a high accuracy to predict imminent spontaneous delivery within 7 days by women with preterm labor and cervical dilatation <3 cm in clinical practice.

The Short Cervix: A Critical Analysis of Diagnosis and Treatment

A short cervix in the second trimester is a significant risk factor for spontaneous preterm birth, preterm prelabor rupture of membranes, and subsequent adverse perinatal outcome. The pathophysiology is complex and multifactorial with inflammatory and/or infectious processes often involved. Biomarkers have been developed in an effort to predict preterm birth with varying degrees of success. The treatment options of cerclage, progesterone, pessary, and combination therapy are reviewed. Evidence-based protocols are summarized for singleton and multiple gestation.

Accuracy of the combination of commercially available biomarkers and cervical length measurement to predict preterm birth in symptomatic women: A systematic review

An accurate prognostic method for preterm birth (PTB) could avoid unnecessary treatment(s) with potentially negative effects. The objective was to explore the prognostic accuracy of commercially available bedside cervicovaginal biomarker tests in combination with cervical length (CL) compared to CL measurement alone and/or a biomarker test alone, for PTB within 7 days after testing symptomatic women at 22-34 weeks. The MEDLINE, Cochrane, Embase and Web of Science databases were searched from inception to August 28th, 2019. Seven hundred and eight articles were identified and screened using Rayyan. Studies reporting on the predictive accuracy of combined tests compared to CL or biomarker alone for the prediction of PTB within 7 days of testing in symptomatic women with intact membranes were included. A piloted data extraction form was used. Direct comparisons of the prognostic accuracy of the combination test with CL measurement or a biomarker alone were done, as well as comparisons of prognostic accuracy of the included combination tests (indirect comparisons). Twelve articles were included (seven on fetal fibronectin, four on phosphorylated insulin-like growth factor binding protein-1, one comparing both). A variety of CL cut-offs was reported. The results could not demonstrate superiority of a combination method compared to single methods. Due to data scarcity and quality, the superiority of either predictive test for PTB, either combination or single, cannot be demonstrated with this systematic review. We recommend further research to compare available biomarkers.

A diagnostic profile on the PartoSure test

Introduction: Preterm birth (PTB) is common, occurring in over 10% of all live births globally, and is increasing worldwide. The limitations of traditional biomarkers of PTB, such as fetal fibronectin (fFN) and phosphorylated insulin-like growth factor-binding protein-1 (phIGFBP-1) have been well demonstrated in the literature. Therefore, augmenting clinical assessment with newer biomarkers, such as placental alpha macroglobulin-1 (PAMG-1); PartoSure, has the potential to improve disease monitoring and the best interventions. Areas covered: The present expert opinion evaluates the utility and limitations of PAMG-1; PartoSure as a biomarker for PTB in light of the current literature. Expert opinion: Although fFN, phIGFBP-1 and PAMG-1; PartoSure test had similar negative predictive value (NPV) and negative likelihood ratio (LR-), the PAMG-1; PartoSure test had the highest specificity, positive predictive value (PPV), and positive likelihood ratio (LR+) across all at-risk pregnant women. Although findings of this review may be encouraging, the PartoSure test should not be interpreted as absolute evidence for prediction of PTB. The PartoSure test result should always be used in conjunction with information available from the clinical evaluation of the pregnant woman and other diagnostic procedures such as cervical examination, assessment of uterine activity, and evaluation of other risk factors.

Role of cervical length and placental alpha microglobulin-1 to predict preterm birth

INTRODUCTION

Preterm labor is the leading cause of premature mortality and morbidity. Therefore, to rule-in and rule-out preterm delivery is a very important issue in our clinical practice.

OBJECTIVE

The aim of this study was to investigate the value of placental alpha microglobulin-1 (PAMG-1) molecule positivity in cervicovaginal secretions of women who have a CL <25 mm and presenting with preterm labor symptoms to predict spontaneous preterm birth within seven days.

MATERIALS AND METHODS

This was a prospective cohort study conducted in Ankara University Department of Obstetrics and Gynecology between August 2017 and February 2019 on the patients who had Preterm labor symptoms, <25 mm transvaginal cervical length (CL), clinically intact membranes. The primary outcome of the study was the power of CL and PAMG-1 positivity on the prediction of preterm birth in seven days.

RESULTS

Sensitivity and specificity values of PAMG-1 in our study population to predict spontaneous preterm birth in seven days were calculated 52.94% and 98.84%, respectively, negative predictive value (NPV) and positive predictive value (PPV) were calculated 91.4% and 90%, respectively. When we investigated our data according to different CL cutoffs, sensitivity and NPV for 20 mm cutoff were 88.24% and 96.3% that was better than PAMG-1, but specificity and PPV were 60.47% and 30.61%, respectively, that was more ineffective than PAMG-1. If we calculate the values according to 15 mm and 10 mm CL cutoffs sensitivity values were 58.8% and 23.53%, specificity values were 81.4% and 91.86%, NPV were 90.9% and 85.87%, PPV were 38.46% and 36.36%, respectively. Finally, accuracy value of PAMG-1 to predict spontaneous preterm birth in seven days was 91.26% that was better than other CL cutoffs (20 mm, 15 mm, and 10 mm).

CONCLUSION

PAMG-1 molecule with high NPV and PPV (91.4% and 90%) combination will contribute our clinical decision on the population who had preterm labor symptoms and a CL shorter than 25 mm.

Evaluation of placental alpha microglobulin-1(PAMG1) accuracy for prediction of preterm delivery in women with the symptoms of spontaneous preterm labor; a comparison with cervical length and number of contractions

Introduction: Since the capacity of tertiary centers is limited, identifying women with the risk of preterm delivery is crucial amongst women who refer to hospitals with threatened preterm labor.Objective: The purpose of the present study was to evaluate the accuracy of the placental alpha microglobulin-1 (PAMG-1) test for identifying women who referred to hospitals with signs of spontaneous preterm labor and ultimately delivered within ≤48 h and ≤7 of testing and ≤37 weeks of gestation and its comparison with cervical length of <25 mm and number of contractions.Materials and methods: A prospective observational study was performed on women with the signs of spontaneous preterm labor. Placental alpha microglobulin-1 (PAMG-1) was evaluated in vaginal secretion. Cervical length (CL) and number of contractions were evaluated and recorded. The test to- spontaneous- delivery interval was documented. Sensitivity (SN), specificity (SP), accuracy rate of the PAMG-1, cervical length of <25 mm and number of contractions in prediction of spontaneous preterm delivery within ≤48 h, ≤7 days and preterm delivery (≤37 weeks of gestation) were calculated.Results: One hundred eighty women finished the study. 44 women had positive PAMG-1 test and 58 women had cervical length of <25 mm. Women with a positive PAMG-1 were more likely to deliver within ≤48 h (p < .0001), ≤7 days (p < .0001), and before 37 weeks (p < .0001), compared to the women who had a negative test. For delivery within ≤48 h, ≤7 days and ≤37 weeks, specificity (SP) of the PAMG-1; was statistically higher than cervical length of <25 mm and contractions of 12-17/hr but not contractions of ≥18/hr. PAMG-1 showed a higher accuracy rate than cervical length of <25 mm, contractions of 12-17/hr and contractions of ≥18/hr for deliveries within ≤48 h (78.9, 55.3, 48.9, and 69.44%, respectively) and ≤7 days (76.1, 55.32, 55, and 65.56%, respectively). For deliveries before 37 weeks; the PAMG-1 test showed higher LR + than CL of <25 mm, contractions of 12-17/hr and contractions of ≥18/hr [10.24 (2.57-40.86), 2.01 (1.24-3.23), 1.30 (1.05-1.62), and 5.12 (1.24-21.11), respectively]. PPV for deliveries within ≤48 h and ≤7 days for PAMG-1 was greater than cervical length of <25 mm and number of contractions, however, NPV did not show a significant difference.Conclusion: PAMG-1 test showed a higher accuracy rate for prediction of delivery within ≤48 and ≤7 days in comparison with cervical length of <25 mm and number of contractions. Also, PAMG-1 test had a higher positive likelihood ratio for deliveries at ≤37 weeks. PPV for deliveries within ≤48 h and ≤7 days for PAMG-1 was greater than cervical length of <25 mm and number of contractions, however, NPV did not show a significant difference.