Quantitative analysis for grading uterine electromyography activities during labor.

BACKGROUND: The strength of uterine contraction is one of the decisive factors for labor progression and parturition. Clinicians usually encounter difficulties in early identification of inadequate contractions and in oxytocin treatment. Electromyography-an emerging technology for uterine contraction monitoring-can quantify the intensity of myoelectric activity of uterine contraction. Therefore, grading patients with different uterine contraction intensities by electromyography is of great significance to the clinical intensive management of uterine contraction and labor process. OBJECTIVE: This study aimed to quantify and grade electromyography activity during the latent phase of the first stage of labor and explore its relationship with oxytocin treatment and length of labor. STUDY DESIGN: We performed a retrospective cohort study to identify electromyography parameters as a predictor for oxytocin treatment and length of labor among a cohort of term singleton primipara (n=508) during the latent phase who delivered in Guangzhou between August 2018 and December 2021. The electromyography parameters were graded according to the quartile method, and the significance of grading and delivery outcome was explored. Univariate and multivariate logistic regression were used to determine the predictors of oxytocin treatment. RESULTS: Maternal gestational age (adjusted risk ratio, 1.2; 95% confidence interval, 1.0-1.5), root mean square (adjusted risk ratio, 0.01; 95% confidence interval, 0.004-0.03), and power (adjusted risk ratio, 0.02; 95% confidence interval, 0.01-0.05) were significant predictors of oxytocin argumentation. The low electromyography activity group had a longer first stage labor and total labor time and were more likely to use oxytocin. CONCLUSION: Electromyography parameters root mean square and power had high predictive values for later oxytocin treatment among patients with spontaneous labor. Patients with low-grade electromyography were more likely need oxytocin treatment. Electromyography grading is very important for its clinical promotion and use, and it could lead to more reliable analyses of oxytocin treatments and eventually to more effective interventions to prevent prolonged labor.

Nicotine ameliorates inflammatory mediators in RU486 induced preterm labor model through activating cholinergic anti-inflammatory pathway.

BACKGROUND: Preterm birth is a global public health threat. Inflammatory reaction is thought to mediate preterm birth. The role of nicotine, an anti-inflammatory agent that is mediated by cholinergic anti-inflammatory pathways (CAP), remains unclear in the pathogenesis. METHODS: Pregnant rats were randomly divided into four groups (20 rats each): pregnant control group (P), RU486-treated group (PTL), RU486 and nicotine-treated group (PTL + N), RU486, nicotine and α-BGT treated group (PTL + N + A). Rats were administered RU486 (1.0 mg/kg) by subcutaneous injection on gestational day (GD) 18 to establish PTL model. Subcutaneous injection of nicotine (1 mg/kg) was administered daily from GD 16 to 18. α-BGT (1 µg/kg) was administrated subcutaneously in two sessions and each session was 30 min prior to nicotine. TNF-α, IL-1ß, IL-4, IL-6, IL-10 in myometrium and serum were detected by Luminex. Macrophage infiltration and α7nAChR were detected by IHC. RESULTS: We established a RU486-induced preterm labor rat model. Preterm labor was associated with a striking upregulation inflammatory mediators and increased macrophage infiltration. Nicotine significantly prolonged gestation (P < 0.05) and α-BGT treatment reversed the prolonged interval (P < 0.05). The cytokines all markedly elevated at 12 h, but deceased after delivery (P < 0.05). The IL-1ß and TNF-α in serum were significantly increased in PTL group vs P group (P < 0.05), and decreased after nicotine treatment (P < 0.05). The cytokines IL-1ß, IL-4, IL-6, IL-10 and TNF-α in myometrium increased as the same trend as in serum. Nicotine treatment also downregulated the expression of α7nAChR in pregnant tissue. CONCLUSION: We confirmed the increased inflammation in preterm birth. Nicotine was able to down-regulate the inflammatory mediates and prolong the pregnant duration in PTL model, which might be induced by activating α7nAChR through CAP. This study provides a novel evidence supporting the future development of therapeutic target for preterm birth.

Uterine slow wave: directionality and changes with imminent delivery.

Objective.The slow wave (SW) of the electrohysterogram (EHG) may contain relevant information on the electrophysiological condition of the uterus throughout pregnancy and labor. Our aim was to assess differences in the SW as regards the imminence of labor and the directionality of uterine myoelectrical activity.Approach. The SW of the EHG was extracted from the signals of the Icelandic 16-electrode EHG database in the bandwidth [5, 30] mHz and its power, spectral content, complexity and synchronization between the horizontal (X) and vertical (Y) directions were characterized by the root mean square (RMS), dominant frequency (domF), sample entropy (SampEn) and maximum cross-correlation (CCmax) of the signals, respectively. Significant differences between parameters at time-to-delivery (TTD) ≤7 versus >7 days and between the horizontal versus vertical directions were assessed.Main results.The SW power significantly increased in both directions as labor approached (TTD ≤ 7d versus >7d (mean±SD):RMSx = 0.12 ± 0.10 versus 0.08 ± 0.06 mV;RMSy = 0.12 ± 0.09 versus 0.08 ± 0.05 mV), as well as the dominant frequency in the horizontal direction (domFx= 9.1 ± 1.3 versus 8.5 ± 1.2mHz) and the synchronization between both directions (CCmax= 0.44 ± 0.16 versus 0.36 ± 0.14). Furthermore, its complexity decreased in the vertical direction (SampEny= 6.13·10-2 ± 8.7·10-3versus 6.50·10-2 ± 8.3·10-3), suggesting a higher cell-to-cell electrical coupling. Whereas there were no differences between the SW features in both directions in the general population, statistically significant differences were obtained between them in individuals in many cases.Significance.Our results suggest that the SW of the EHG is related to bioelectrical events in the uterus and could provide objective information to clinicians in challenging obstetric scenarios.

A study of uterine inertia on the spontaneous of labor using uterine electromyography.

OBJECTIVE: The purpose of this study is to analyze uterine electromyography burst patterns in patients with spontaneous labor and patients with uterine inertia. MATERIALS AND METHODS: Uterine electromyography was recorded using 4 silver/silver chloride electrodes placed periumbilical. Thirty women in the spontaneous labor were enrolled. Uterine electromyography was also recorded from patients with uterine inertia before and after oxytocin treatment. EMG bursts were characterized by analysis of multiple variables including burst frequency, duration, root mean squared, amplitude, and total power. RESULTS: There were significant reductions (P < .01) in all EMG burst characteristics. In addition, uterine electromyography parameters were all increased after oxytocin treatment and were comparable (P > .05) to patients in spontaneous labor. CONCLUSIONS: Uterine electromyography can be used effectively to distinguish patients progressing with spontaneous labor from patients that develop uterine inertia. Uterine inertia is characterized by reduced EMG activity and failure of cervical dilation. Uterine electromyography is a quantitative, non-invasive assessment tool that contributes to the diagnosis, evaluation and management of patients with spontaneous labor and uterine inertia.

Uterine electromyography (EMG) measurements to predict preterm caesarean section in patients with complete placenta previa.

The objective of the study was to evaluate uterine electrical activity (EA) with EMG methods in pregnant women with complete placenta previa with preterm caesarean section (CS). This prospective study included 78 patients with complete placenta previa who were recorded for uterine EA activity from 32 to 34 weeks of gestation. The clinical and the uterine EMG burst characteristics, that are responsible for contractions, were compared between a preterm CS group (case group, n = 33) and an elective control group (control group, n = 45). The uterine EA burst duration was longer in the case group compared with the control group (28.79 ± 3.75 vs 19.35 ± 2.56 s; p < .001). Also, the number of burst per 30 min was also higher in the case group compared with the control group (3.28 ± 0.18 vs 1.72 ± 0.22; p < .001), Similarly, the RMS was higher in the case group compared with the control group (0.07 ± 0.01 vs 0.04 ± 0.01 mV; p = .041). In addition, the PDS was higher in the case group compared with the control group (0.47 ± 0.03 vs 0.39 ± 0.02 Hz; p = .023). This study demonstrates that women with complete placenta previa have higher uterine EA at 32-34 weeks of gestation and this is associated with a higher risk of preterm CS due to massive vaginal bleeding.IMPACT STATEMENTWhat is already known on this subject? Antepartum massive bleeding in complete placenta previa causes maternal and foetal mortality and morbidity, currently there is no effective method to predict it.What do the results of this study add? This study showed in patients with complete placenta previa who were delivered preterm via emergent caesarean section, the uterine electrical activity measured by uterine electromyography (EMG) at 32-34 weeks of gestation had an active patternWhat are the implications of these findings for clinical practice and/or further research? Uterine EMG is a potential tool to measure uterine electrical activity and can guide clinical management of patients with complete placenta previa, further study are needed to confirm its effectiveness in a large sample size.

Evaluation of cervical maturity by cervical collagen measurement using light-induced fluorescence (LIF) during pregnancy.

OBJECTIVE: The study aimed to evaluate cervical ripening by measuring cervical collagen levels in non-pregnant women, women with a normal pregnancy, and postpartum women by light-induced fluorescence (LIF). METHODS: Cervical collagen content in normal pregnant women (n = 165) at various times of gestation was measured by LIF with a collascope, which is specifically designed to measure fluorescence of collagen. Cervical LIF in non-pregnant women (n = 12) and postpartum women (n = 14) was also detected. The demographic characteristics of women at various times were recorded. The Bishop score at 40 to 41 gestational weeks (n = 37) before the onset of labor was analyzed. RESULTS: Cervical LIF values progressively declined from the non-pregnant state to late gestation (R = -0.836) and reached their lowest levels during parturition and then increased at postpartum. LIF values and the Bishop score were significantly negatively correlated (R = -0.83). In patients with a Bishop score ≥6, the first stage of labor was shortened with a decrease in LIF values (R = 0.718). CONCLUSIONS: Cervical collagen levels as measured by LIF could be a useful method for evaluating cervical maturity.

Nicotine protects fetus against LPS-induced fetal growth restriction through ameliorating placental inflammation and vascular development in late pregnancy in rats.

Our previous work has shown that nicotine suppressed lipopolysaccharide (LPS)-induced placental inflammation by inhibiting cytokine release as well as infiltration of leukocytes into the placenta through the cholinergic anti-inflammatory pathway. Nicotine also increased fetal survival and restored pup weight. In the present study, we aim to further investigate if fetal growth restriction (FGR) occurs with LPS treatment, and evaluate the protective effects of nicotine on fetuses in late gestation of rats. Pregnant Sprague-Dawley rats were divided into control group, nicotine group, LPS group and LPS + nicotine group. Rats were first pretreated with nicotine or vehicle by subcutaneous injection on gestation day (GD)14 and GD15, followed by LPS or vehicle intraperitoneal injection on GD16, and were killed on GD18. Loss of fetuses, number and weights of live fetuses and weights of placentas were recorded. Placentas were collected to evaluate placental pathology and determine inflammatory cytokines and vascular endothelial growth factor (VEGF) levels. We found that LPS treatment increased levels of placental inflammatory cytokines and placental pathological damage, decreased levels of VEGF, reduced number of live fetuses and induced FGR. Pretreatment with nicotine reversed LPS-induced high levels of placental inflammatory cytokines, low levels of placental VEGF and placental pathological damage, then rescued the number and weights of live fetuses. These data demonstrated that activation of the cholinergic anti-inflammatory pathway by nicotine protected fetus against LPS-induced FGR through ameliorating placental inflammation and vascular development in late pregnancy in rats. It may be an alternative therapeutic strategy for inflammation- induced FGR in late pregnancy.

Measurement of Uterine and Abdominal Muscle Electromyography in Pregnant Women for Estimation of Expulsive Activities during the 2nd Stage of Labor.

BACKGROUND: The progression of labor and delivery of the fetus is dependent upon uterine contractions and the voluntary effort of abdominal muscle contractions. A good monitor of uterine contractions and pushing is necessary for obstetrical care. Electromyography (EMG) is the underlying basis for contractility of muscle including the myometrium. OBJECTIVES: The aim of this study was to determine the relationship between EMG activity of uterine and abdominal muscles and the duration of the 2nd stage of labor in pregnant women. METHODS: EMG of both uterine and abdominal muscles was simultaneously recorded from electrodes placed on the abdominal surface of 45 active 2nd stage-laboring nulliparous patients. EMG was recorded using filters to separate uterine and abdominal EMG signals, and various EMG signal parameters were analyzed. The duration of the 2nd stage of labor and other maternal and fetal characteristics were also recorded. RESULTS: Uterine EMG bursts precede abdominal bursts and are accompanied by feelings of "urge to push" by the patients. Abdominal root mean square (RMS) and power, but not uterine EMG parameters, are reduced (p< 0.005) in patients with longer labors and linear regression analysis demonstrated a negative correlation to the duration of 2nd stage of labor (p < 0.001). Multivariate linear regression analysis of clinical characteristics (fetal weight, body mass index, placental location, etc.) and parameters of EMG showed that only abdominal RMS is negatively correlated with the duration of labor. CONCLUSIONS: (1) Uterine and abdominal EMG activities reflect the expulsive involuntary (uterine) and voluntary (abdominal) muscular activities during the 2nd stage of labor. (2) RMS and power of abdominal EMG diminish with longer labor when uterine EMG intensities are similar. (3) Recording of uterine and abdominal muscle activity provides objective evaluation of the muscle activity during the 2nd stage of labor and may aid in the evaluation of any interventions.

Effects of vaginal progesterone for maintenance tocolysis on uterine electrical activity.

AIM: The effectiveness of vaginal progesterone for maintenance tocolysis after arrested preterm labor remains controversial. Myometrial contractility can be assessed objectively and non-invasively after progesterone treatment by monitoring uterine electromyography (EMG). We examined the effects of vaginal progesterone on uterine EMG after successful acute tocolysis. METHODS: This was a randomized, double-blind, single-center study performed between 2012 and 2015. Thirty women who experienced preterm labor between 24 0/7 and 33 6/7 weeks were randomly allocated to groups administered either 400 mg vaginal progesterone or a placebo 48 h after acute tocolysis. EMG measurements were taken prior to and 1 h and 2 h following treatment. Mann-Whitney U tests were used to compare EMG power density spectrum peak frequency and peak amplitude, propagation velocity of EMG signals, and duration and number of EMG bursts in 30 min recordings between the groups (P < 0.05). RESULTS: EMG propagation velocity was higher in patients receiving the placebo compared to those treated with progesterone at 1 h (27.83 ± 10.66 vs 15.60 ± 2.94 cm/s) and 2 h (26.97 ± 13.39 vs 15.12 ± 2.58 cm/s) following treatment (P = 0.001). PDS peak frequencies were higher in the placebo compared to the progesterone group at 2 h following treatment (0.54 ± 0.11 vs 0.44 ± 0.06 Hz; P = 0.003). CONCLUSIONS: Treatment of 400 mg of vaginal micronized progesterone as maintenance tocolysis significantly reduces the propagation velocity of electrical signals within the myometrium and is associated with a shift toward lower uterine electrical signal frequencies.

Choline Supplementation During Pregnancy Protects Against Gestational Lipopolysaccharide-Induced Inflammatory Responses.

OBJECTIVES: To estimate the effects and mechanisms of choline, an essential nutrient and a selective α7 nicotinic acetylcholine receptor (α7nAChR) agonist, on the prevention of symptoms and the effects on the cholinergic anti-inflammatory pathways (CAP) in a lipopolysaccharide (LPS)-induced inflammatory response in a rat model. METHODS: Inflammation was induced by LPS treatment (1.0 µg LPS/kg body weight) on gestational day (GD) 14. Nonpregnant and pregnant Sprague Dawley rats were placed on a normal choline diet (1.1 g/kg) or supplemented choline diet (5.0 g/kg) from GDs 1 to 20. Systolic blood pressure (SBP), urinary albumin, and pregnancy outcomes were recorded. On GD 20, serum and placentas were assayed for cytokines. Western blots were used to determine the expression of placenta α7nAChR and components of the α7nAChR-CAP, including nuclear factor-κB (NF-κB) and protein kinase B (AKT). Immunohistochemistry was used to localize placental sites for the p65 subunit of NF-κB. RESULTS: Lipopolysaccharide significantly increased SBP and urinary albumin and decreased pregnancy outcomes, and these effects were partially reversed by higher choline treatment. Choline supplementation also significantly attenuated the LPS-induced increase in serum and placental inflammatory cytokines, decreased the expression of placental α7nAChR, lowered the activation of NF-κB signaling in placenta mononuclear cells, and inhibited placental AKT phosphorylation. CONCLUSION: This study confirms that LPS induces inflammatory conditions in pregnant rats and shows that choline supplementation protects against the inflammatory symptoms through its action on α7nAChR and CAP. These observations have important implications for the prevention and treatment of inflammatory responses associated with pregnancy.

Optimal routes of administration, vehicles and timing of progesterone treatment for inhibition of delivery during pregnancy.

OBJECTIVES: Progestins, notably progesterone (P4) and 17 alpha hydroxyprogesterone caproate, are presently used to treat pregnant women at risk of preterm birth. The aim of this study was to assess the optimal treatment options for progesterone (P4) to delay delivery using a sensitive bioassay for progesterone. STUDY DESIGN: Pregnant rats, known to be highly sensitive to progestins, were treated with P4, including Prochieve® (also known as Crinone®), in various vehicles from day 13 of gestation and in late gestation, days 19 to 22, and delivery times noted. Various routes of administration of P4 and various treatment periods were studied. RESULTS: Use of micronized P4 by rectal, subcutaneous injection (sc) and topical (transdermal) administration in various oils all significantly (P<0.05-<0.001) delay delivery, but vaginal Prochieve® did not. Administration of P4 in late gestation also prevented (P<0.001) delivery even when given 8h before delivery. CONCLUSIONS: Prochieve® possesses little biological activity to suppress delivery in a sensitive bioassay system and suggests that this preparation may be of little value in prevention and inhibition of preterm birth. Further, this study shows: 1) Inhibition of delivery is increased with P4 treatments when given subcutaneously or topically. 2) P4 in fish oil provides the best vehicle for topical treatment and may be an effective treatment of preterm birth. 3) P4 in fish oil also delays delivery even when treatment begins just prior to normal delivery. 4) To prevent preterm birth in pregnant women, randomized controlled studies are needed with a potent progestin using better formulations and routes of administration.

Uterine and Abdominal Muscle Electromyographic Activities in Control and PCEA-Treated Nulliparous Women During the Second Stage of Labor.

OBJECTIVE: Patient-controlled epidural analgesia (PCEA), used to relieve pain during delivery, delays labor but the mechanism is unknown. The aim was to investigate the effects of PCEA on uterine and abdominal muscles electromyographic (EMG) activity during the second stage of labor. METHODS: This study included 45 nulliparous pregnant women without PCEA, 42 women with standard PCEA treatment given during the first stage of labor and stopped near the end of the first stage, and 22 women with standard PCEA treatment with continued use throughout the first and second stages of labor. The EMG signals were recorded from the abdominal surface using PowerLab hardware and LabChart software (ADInstruments, New South Wales, Australia) and filtered to separate uterine and abdominal EMG. Various EMG burst parameters were obtained. RESULTS: There are no differences ( P > .05) in the age, body mass index, fetal weight, and Apgar scores between the patients from the various groups. PCEA (both stopped and continued) inhibits ( P < .05) duration, number of bursts, and root mean square of uterine EMG. PCEA also produces statistically significant ( P < .001) reductions in abdominal EMG. The decrease in EMG activity is accompanied by a significant ( P < .001) prolongation of the second stage duration (PCEA continued = 95.08 ± 8.60 minutes, PCEA stopped = 79.39 ± 6.25 minutes, no PCEA = 61.00 ± 7.23 minutes). CONCLUSION: PCEA suppresses uterine and abdominal muscle EMG during the second stage of labor but inhibition depends upon the treatment schedule. PCEA prolongs the duration of labor by inhibition of uterine and abdominal muscle and neural activity.

Simultaneous Recording and Analysis of Uterine and Abdominal Muscle Electromyographic Activity in Nulliparous Women During Labor.

OBJECTIVE: To record and characterize electromyography (EMG) from the uterus and abdominal muscles during the nonlabor to first and second stages of labor and to define relationships to contractions. METHODS: Nulliparous patients without any treatments were used (n = 12 nonlabor stage, 48 during first stage and 33 during second stage). Electromyography of both uterine and abdominal muscles was simultaneously recorded from electrodes placed on patients' abdominal surface using filters to separate uterine and abdominal EMG. Contractions of muscles were also recorded using tocodynamometry. Electromyography was characterized by analysis of various parameters. RESULTS: During the first stage of labor, when abdominal EMG is absent, uterine EMG bursts temporally correspond to contractions. In the second stage, uterine EMG bursts usually occur at same frequency as groups of abdominal bursts and precede abdominal bursts, whereas abdominal EMG bursts correspond to contractions and are accompanied by feelings of "urge to push." Uterine EMG increases progressively from nonlabor to second stage of labor. CONCLUSIONS: (1) Uterine EMG activity can be separated from abdominal EMG events by filtering. (2) Uterine EMG gradually evolves from the antepartum stage to the first and second stages of labor. (3) Uterine and abdominal EMG reflect electrical activity of the muscles during labor and are valuable to assess uterine and abdominal muscle events that control labor. (4) During the first stage of labor uterine, EMG is responsible for contractions, and during the second stage, both uterine and abdominal muscle participate in labor.

Effect of obesity on preterm delivery prediction by transabdominal recording of uterine electromyography.

OBJECTIVE: It has been shown that noninvasive uterine electromyography (EMG) can identify true preterm labor more accurately than methods available to clinicians today. The objective of this study was to evaluate the effect of body mass index (BMI) on the accuracy of uterine EMG in predicting preterm delivery. MATERIALS AND METHODS: Predictive values of uterine EMG for preterm delivery were compared in obese versus overweight/normal BMI patients. Hanley-McNeil test was used to compare receiver operator characteristics curves in these groups. Previously reported EMG cutoffs were used to determine groups with false positive/false negative and true positive/true negative EMG results. BMI in these groups was compared with Student t test (p < 0.05 significant). RESULTS: A total of 88 patients were included: 20 obese, 64 overweight, and four with normal BMI. EMG predicted preterm delivery within 7 days with area under the curve = 0.95 in the normal/overweight group, and with area under the curve = 1.00 in the obese group (p = 0.08). Six patients in true preterm labor (delivering within 7 days from EMG measurement) had low EMG values (false negative group). There were no false positive results. No significant differences in patient's BMI were noted between false negative group patients and preterm labor patients with high EMG values (true positive group) and nonlabor patients with low EMG values (true negative group; p = 0.32). CONCLUSION: Accuracy of noninvasive uterine EMG monitoring and its predictive value for preterm delivery are not affected by obesity.

Nicotine inhibits LPS-induced cytokine production and leukocyte infiltration in rat placenta.

INTRODUCTION: Previous work conducted by our group has shown that nicotine reduces lipopolysaccharide (LPS)-induced systemic inflammatory responses and protects fetuses in pregnant Sprague-Dawley (SD) rats. In the present study, we aim to evaluate the influence of nicotine on rat placenta, including cytokine release, leukocyte infiltration, and α7 nicotinic acetylcholine receptor (α7-nAChR) expression. METHODS: Placental tissues of SD rats on gestation day 14 (GD14) were obtained and cultured in the presence or absence of LPS and/or nicotine. Culture media after 24 h were analyzed for cytokines release using Luminex. Other pregnant SD rats were first pretreated with nicotine on GD14 and GD15, followed by LPS injection on GD16. Placentas were collected on GD18 for H&E staining to evaluate leukocyte density and for real-time PCR and western blotting to identify the α7-nAChR expression in different groups. RESULTS: Nicotine suppresses LPS-stimulated placental proinflammatory cytokines (IL-1, IL-2, IL-6, TNF-α, IFN-γ) production except IL-17 in vitro, and reduces leucocytes infiltration in the placental chorionic plate caused by LPS in vivo. Moreover, LPS increases the α7-nAChR protein expression in placentas while pretreatment of nicotine inhibits it. DISCUSSION: These data show that nicotine suppresses LPS-induced placental inflammation by inhibition of cytokine release and infiltration of leukocytes into the placenta, and regulates the increased expression of α7-nAChR in placenta after LPS treatment. Nicotine and other nicotinic agonists may be an alternative therapeutic strategy for placental inflammation.

Changes in ectocervical surface area in women throughout pregnancy compared to non-pregnant and postpartum states.

OBJECTIVE: The objective of this study is to estimate changes in the surface area of the ectocervix (CA) in women during pregnancy and compare this to postpartum and non-pregnant states. METHODS: CA was evaluated in 210 normal nulliparous women divided into groups from early to late gestation, 40 postpartum women, and 25 non-pregnant women. CA in cm(2) was estimated from analysis of images taken with an endoscope of the cervical face and an mm scale. An mm scale was also used to determine fornix length and fornix area computed. RESULTS: The face, fornix, and total areas of the CA of non-pregnant and postpartum groups are significantly smaller (p < 0.001) than these areas in groups during pregnancy. Generally, the CA of the face, fornix, and total area are also less in early pregnancy compared with late gestation (p < 0.01 to <0.001). Total CA correlates with gestational age (r = 0.196, p < 0.004). CONCLUSIONS: (1) During pregnancy, CA slowly and progressively increases to >75% area compared with CA of non-pregnant patients and then reverts back to low CA postpartum. (2) Increases in CA during pregnancy occur in both the face and fornix areas. (3) Increases in CA reflect enlargement in cervical volume and remodeling during pregnancy.

Uterine electromyography during active phase compared with latent phase of labor at term.

INTRODUCTION: In a prospective study in a tertiary university hospital we wanted to determine whether uterine electromyography (EMG) can differentiate between the active and latent phase of labor. MATERIAL AND METHODS: Thirty women presenting at ≥37(0/7) weeks of gestation with regular uterine contractions, intact membranes, and a Bishop score <6. EMG was recorded from the abdominal surface for 30 min. Latent phase was defined as no cervical change within at least 4 h. Student's t-test was used for statistical analysis (p ≤ 0.05 significant). Diagnostic accuracy of EMG was determined by receiver operator characteristics (ROC) analysis. The integral of the amplitudes of the power density spectrum (PDS) corresponding to the PDS energy within the "bursts" of uterine EMG activity was compared between the active and latent labor groups. RESULTS: Seventeen (57%) women were found to be in the active phase of labor and 13 (43%) were in the latent phase. The EMG PDS integral was significantly higher (p = 0.02) in the active (mean 3.40 ± 0.82 µV) compared with the latent (mean 1.17 ± 0.33 µV) phase of labor. The PDS integral had an area under the ROC curve (AUC) of 0.80 to distinguish between active and latent phases of labor, compared with number of contractions on tocodynamometry (AUC = 0.79), and Bishop score (AUC = 0.78). The combination (sum) of PDS integral, tocodynamometry, and Bishop score predicted active phase of labor with an AUC of 0.90. CONCLUSIONS: Adding uterine EMG measurements to the methods currently used in the clinics could improve the accuracy of diagnosing active labor.

Effects of Patient-Controlled Epidural Analgesia on Uterine Electromyography During Spontaneous Onset of Labor in Term Nulliparous Women.

OBJECTIVE: To investigate the effect of patient-controlled epidural analgesia (PCEA) on uterine electromyography (EMG) activity in term pregnant women during labor. METHODS: Nulliparous pregnant women in spontaneous term labor (N = 30) were enrolled (PCEA group, n = 20 and control group, n = 10). Five time periods (30 minutes each) were defined for noninvasive abdominal recordings and analysis of uterine EMG activity, that is, period I: before PCEA treatment with 2-cm cervical dilation; periods II to IV: each period successively at 30, 60, and 120 minutes after PCEA; and period V: second stage of labor with cervix at 10 cm dilation. Control patients without PCEA were monitored during the same times. The number of bursts/30 min, power density spectrum peak frequency, mean amplitude, and duration of uterine EMG bursts were measured to assess uterine EMG activity. Maternal, fetal, and labor characteristics were also recorded. Data were analyzed by analysis of variance followed by other tests. RESULTS: Electromyography parameters are significantly lower (P < .001) after PCEA (periods II to IV) compared to controls but similar between groups by period V (P > .05). Also, patients with PCEA have a slower rate of cervical dilation (P < .003, period IV only) and longer labor in both stage 1 and stage 2 (P < .05). All patients have similar (P > .05) positive labor outcomes. CONCLUSIONS: Patient-controlled epidural analgesia initially suppresses uterine EMG and slows cervical dilation thereby prolonging labor. However, the EMG activity recovers with labor progress with no effects on delivery outcomes.

Direct electrical stimulation softens the cervix in pregnant and nonpregnant rats.

OBJECTIVE: The objective of the study was to determine the effects of electrical stimulation (ES) on cervical ripening in pregnant and nonpregnant rats. STUDY DESIGN: Timed pregnant and nonpregnant Sprague-Dawley rats (n = 6-7/group) were used. Cervical ES for pregnant rats was performed in vivo on day 15 of gestation by inserting an electrical probe into the vagina in contact with the cervix. Parameters of ES varied from 0.1 to 0.2 mA, 10 pulses per second, 20 milliseconds pulse duration, and repeating pulses for 15, 30, 60, and 120 minutes for pregnant ES groups and similar times for sham control groups with electrode but without ES. Nonpregnant ES groups were stimulated with only 0.2 mA for 30 minutes. Cervical collagen was measured in controls and following ES at various times using light-induced fluorescence (LIF) of collagen. Photographs were taken following ES, and some rats were killed, the cervices were isolated, and cervical extensibility was estimated. RESULTS: LIF values of pregnant rats are significantly lower (P < .001) and extensibility greater (P < .05) in the ES treatment groups compared with the control groups on days 16 and 17 of pregnancy. Similarly LIF is lower (P < .05) and extensibility values greater (P < .05) in nonpregnant rats treated with ES. No adverse effects, including altered delivery time, pup weights, or damage to cervix, were produced by low current levels of ES needed to soften the cervix. CONCLUSION: The following conclusions were reached: (1) application of ES rapidly produces softening and ripening of the cervix in pregnant and nonpregnant rats; (2) ES treatment does not produce early delivery; (3) the exact mechanism for ES ripening is not yet known; and (4) ES might be used clinically to ripen the cervix when needed.