The effect of intrapartum dental support use among nulliparous during the second stage of labor - a randomized controlled study

Uterine electrical activity, oxytocin and labor: translating electrical into mechanical

PURPOSE

Uterine activity plays a crucial role in labor, especially when utero-tonic materials are administered. We aimed to determine the electrical responsiveness of the uterine musculature to labor augmentation with oxytocin using electrical uterine myography (EUM) technology, and to assess whether the kinetics of the EUM device may serve as a predictor for successful vaginal delivery.

METHODS

EUM prospectively measured electrical uterine activity in women with singleton gestations at term (≥ 37 + 0 weeks) undergoing labor augmentation by oxytocin administration. The results were reported as the EUM index, which represented the mean electrical activity in 10-min intervals and measured in units of microwatt per second (mW/s). Measurements were performed at least 30 min before oxytocin initiation and until at least four contractions per 10 min were recorded by standard tocodynamometry. The delta EUM index was defined as the difference between the mean EUM index before and after the initiation of oxytocin.

RESULTS

The mean EUM index increased significantly during oxytocin augmentation in all the parturients (P < 0.001). Mean and minimum (but not maximum) uterine electrical activity during oxytocin infusion correlated with the baseline uterine activity. The delta EUM index was not significantly affected by demographic or obstetric parameters. There was no correlation between the delta EUM index and time to delivery or the mean EUM index during oxytocin administration and time to delivery.

CONCLUSIONS

Uterine electrical activity as evaluated by EUM is significantly intensified following oxytocin administration, regardless of obstetrical characteristics, and is correlated with the baseline uterine electrical activity prior to oxytocin infusion.

Pushing/bearing down methods for the second stage of labour

BACKGROUND

Maternal pushing during the second stage of labour is an important and indispensable contributor to the involuntary expulsive force developed by uterine contraction. There is no consensus on an ideal strategy to facilitate these expulsive efforts and there are contradictory results about the influence on the mother and fetus.

OBJECTIVES

To evaluate the benefits and possible disadvantages of different kinds of techniques regarding maternal pushing/breathing during the expulsive stage of labour on maternal and fetal outcomes.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (19 September 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs assessing the effects of pushing/bearing down techniques (type and/or timing) performed during the second stage of labour on maternal and neonatal outcomes. Cluster-RCTs were eligible for inclusion, but none were identified. Studies using a cross-over design and those published in abstract form only were not eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data and assessed risk of bias. Data were checked for accuracy.

MAIN RESULTS

In this updated review, we included 21 studies in total, eight (884 women) comparing spontaneous pushing versus directed pushing, with or without epidural analgesia and 13 (2879 women) comparing delayed pushing versus immediate pushing with epidural analgesia. Our GRADE assessments of evidence ranged from moderate to very low quality; the main reasons for downgrading were study design limitations and imprecision of effect estimates. Overall, the included studies varied in their risk of bias; most were judged to be at unclear risk of bias. Comparison 1: types of pushing: spontaneous pushing versus directed pushingThere was no clear difference in the duration of the second stage of labour (mean difference (MD) 10.26 minutes; 95% confidence interval (CI) -1.12 to 21.64 minutes, six studies, 667 women, random-effects, I² = 81%) (very low-quality evidence). There was no clear difference in 3rd or 4th degree perineal laceration (risk ratio (RR) 0.87; 95% CI 0.45 to 1.66, one study, 320 women) (low-quality evidence), episiotomy (average RR 1.05; 95% CI 0.60 to 1.85, two studies, 420 women, random-effects, I² = 81%), duration of pushing (MD -9.76 minutes, 95% CI -19.54 to 0.02; two studies; 169 women; I² = 88%) (very low-quality evidence), or rate of spontaneous vaginal delivery (RR 1.01, 95% CI 0.97 to 1.05; five studies; 688 women; I² = 2%) (moderate-quality evidence). For primary neonatal outcomes such as five-minute Apgar score less than seven, there was no clear difference between groups (RR 0.35; 95% CI 0.01 to 8.43, one study, 320 infants) (very low-quality evidence), and the number of admissions to neonatal intensive care (RR 1.08; 95% CI 0.30 to 3.79, two studies, 393 infants) (very low-quality evidence) also showed no clear difference between spontaneous and directed pushing. No data were available on hypoxic ischaemic encephalopathy. Comparison 2: timing of pushing: delayed pushing versus immediate pushing (all women with epidural)For the primary maternal outcomes, delayed pushing was associated with an increase of 56 minutes in the duration of the second stage of labour (MD 56.40, 95% CI 42.05 to 70.76; 11 studies; 3049 women; I² = 91%) (very low-quality evidence), but no clear difference in third or 4th degree perineal laceration (RR 0.94; 95% CI 0.78 to 1.14, seven studies. 2775 women) (moderate-quality evidence) or episiotomy (RR 0.95; 95% CI 0.87 to 1.04, five studies, 2320 women). Delayed pushing was also associated with a 19-minute decrease in the duration of pushing (MD -19.05, 95% CI -32.27 to -5.83; 11 studies; 2932 women; I² = 95%) (very low-quality evidence) and an increase in spontaneous vaginal delivery (RR 1.07; 95% CI 1.02 to 1.11, 12 studies, 3114 women) (moderate-quality evidence).For the primary neonatal outcomes, there was no clear difference between groups in admission to neonatal intensive care (RR 0.98; 95% CI 0.67 to 1.41, three studies, n = 2197) (low-quality evidence) and five-minute Apgar score less than seven (RR 0.15; 95% CI 0.01 to 3.00; three studies; 413 infants) (very low-quality evidence). There were no data on hypoxic ischaemic encephalopathy. Delayed pushing was associated with a greater incidence of low umbilical cord blood pH (RR 2.24; 95% CI 1.37 to 3.68, 4 studies, 2145 infants) and increased the cost of intrapartum care by CDN$ 68.22 (MD 68.22, 95% CI 55.37, 81.07, one study, 1862 women).

AUTHORS' CONCLUSIONS

This updated review is based on 21 included studies of moderate to very low quality of evidence (with evidence mainly downgraded due to study design limitations and imprecision of effect estimates).Timing of pushing with epidural is consistent in that delayed pushing leads to a shortening of the actual time pushing and increase of spontaneous vaginal delivery at the expense of an overall longer duration of the second stage of labour and an increased risk of a low umbilical cord pH (based only on one study). Nevertheless, there was no clear difference in serious perineal laceration and episiotomy, and in other neonatal outcomes (admission to neonatal intensive care, five-minute Apgar score less than seven and delivery room resuscitation) between delayed and immediate pushing.Therefore, for the type of pushing, with or without epidural, there is no conclusive evidence to support or refute any specific style as part of routine clinical practice, and in the absence of strong evidence supporting a specific method or timing of pushing, the woman's preference and comfort and clinical context should guide decisions.Further properly well-designed RCTs, addressing clinically important maternal and neonatal outcomes are required to add evidence-based information to the current knowledge. Such trials will provide more complete data to be incorporated into a future update of this review.