Semi-Fowler's positioning, lateral tilts, and their effects on nonstress tests

Maternal posture-physiology interactions in human pregnancy: a narrative review

There are several well-known medical conditions in which posture and gravity interact with natural history, including pregnancy. In this review, we provide a comprehensive overview of interactions between maternal posture and maternal physiology and pathophysiology at rest during pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 644 studies from 1991 through 2021, inclusive, that met our inclusion criteria. We present a narrative review of the resulting literature and highlight discrepancies, research gaps, and potential clinical implications. We organize the results by organ system and, commencing with the neurological system, proceed in our synthesis generally in the craniocaudal direction, concluding with the skin. The circulatory system warranted our greatest and closest consideration-literature concerning the dynamic interplay between physiology (heart rate, stroke volume, cardiac output, blood pressure, and systemic vascular resistance), pathophysiology (e.g., hypertension in pregnancy), and postural changes provide an intricate and fascinating example of the importance of the subject of this review. Other organ systems discussed include respiratory, renal, genitourinary, gastrointestinal, abdominal, and endocrine. In addition to summarizing the existing literature on maternal posture-physiology interactions, we also point out gaps and opportunities for further research and clinical developments in this area. Overall, our review provides both insight into and relevance of maternal posture-physiology interactions vis à vis healthcare's mission to improve health and wellness during pregnancy and beyond.

Impact of maternal posture on fetal physiology in human pregnancy: a narrative review

In numerous medical conditions, including pregnancy, gravity and posture interact to impact physiology and pathophysiology. Recent investigations, for example, pertaining to maternal sleeping posture during the third trimester and possible impact on fetal growth and stillbirth risk highlight the importance and potential clinical implications of the subject. In this review, we provide an extensive discussion of the impact of maternal posture on fetal physiology from conception to the postpartum period in human pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 242 studies from 1991 through 2021, inclusive, that met our inclusion criteria. Herein, we provide a synthesis of the resulting literature. In the first section of the review, we group the results by the impact of maternal posture at rest on the cervix, uterus, placenta, umbilical cord, amniotic fluid, and fetus. In the second section of the review, we address the impact on fetal-related outcomes of maternal posture during various maternal activities (e.g., sleep, work, exercise), medical procedures (e.g., fertility, imaging, surgery), and labor and birth. We present the published literature, highlight gaps and discrepancies, and suggest future research opportunities and clinical practice changes. In sum, we anticipate that this review will shed light on the impact of maternal posture on fetal physiology in a manner that lends utility to researchers and clinicians who are working to improve maternal, fetal, and child health.

Do different positions during a non-stress test affect the maternofetal physiological parameters and comfort in pregnant women?

BACKGROUND

A non-stress test (NST) is an essential diagnostic test performed during pregnancy to assess fetal well-being. It is a recording of fetal movements besides fetal heart rate, indicating fetal biophysiological well-being. As maternal physiology is altered in various positions, apt positioning during the NST is essential for accurate results while ensuring maternal comfort. This study aims to evaluate the effect of different maternal positions, left lateral and semi-fowler's, on NST reactivity, maternal blood pressure, heart rate, and comfort in pregnant women while performing the NST.

MATERIALS AND METHODS

This crossover study evaluated 50 healthy pregnant women between 32 and 40 weeks of gestation with no obstetric complications for the effect of maternal positions on maternofetal physiological parameters and comfort. The NST was performed for 20 min in each position with a washout period of 10 min. The maternofetal physiological parameters were recorded by a calibrated sphygmomanometer and the electrocardiograph interpretations. The maternal comfort was assessed using a maternal comfort rating scale (MCRS) for each position after the NST. Relevant descriptive and inferential statistics are applied to compute the results.

RESULTS

Statistically, there was a significant difference in the mean maternal blood pressure and heart rate between the left lateral and semi-fowler's positions at 0 and 20 min (P = 0.001), whereas within the groups, in the same position at 0 and 20 min, no significant difference was found. There was no significant difference in NST reactivity (P = 0.79) in different positions. There was no significant difference between the MCR scores of women in either of the positions (Z = -1.64, df = 49, P = 0.100).

CONCLUSION

Semi-fowler's position demonstrated favorable maternal blood pressure and heart rate during the NST in the third trimester of pregnancy, though it was clinically not significant. There was no significant difference in the comfort of women in both positions. Hence, either of the positions can be implemented in practice as an alternative position while performing the NST, based on the women's preference.

Antenatal cardiotocography for fetal assessment

BACKGROUND

Cardiotocography (CTG) is a continuous recording of the fetal heart rate obtained via an ultrasound transducer placed on the mother's abdomen. CTG is widely used in pregnancy as a method of assessing fetal well-being, predominantly in pregnancies with increased risk of complications.

OBJECTIVES

To assess the effectiveness of antenatal CTG (both traditional and computerised assessments) in improving outcomes for mothers and babies during and after pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (26 June 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised trials that compared traditional antenatal CTG with no CTG or CTG results concealed; computerised CTG with no CTG or CTG results concealed; and computerised CTG with traditional CTG.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

Six studies (involving 2105 women) are included. Overall, the included studies were not of high quality, and only two had both adequate randomisation sequence generation and allocation concealment. All studies that were able to be included enrolled only women at increased risk of complications.Comparison of traditional CTG versus no CTG showed no significant difference identified in perinatal mortality (risk ratio (RR) 2.05, 95% confidence interval (CI) 0.95 to 4.42, 2.3% versus 1.1%, four studies, N = 1627, low quality evidence) or potentially preventable deaths (RR 2.46, 95% CI 0.96 to 6.30, four studies, N = 1627), though the meta-analysis was underpowered to assess this outcome. Similarly, there was no significant difference identified in caesarean sections (RR 1.06, 95% CI 0.88 to 1.28, 19.7% versus 18.5%, three trials, N = 1279, low quality evidence). There was also no significant difference identified for secondary outcomes related to Apgar scores less than seven at five minutes (RR 0.83, 95% CI 0.37 to 1.88, one trial, N = 396, very low quality evidence); or admission to neonatal special care units or neonatal intensive care units (RR 1.08, 95% CI 0.84 to 1.39, two trials, N = 883, low quality evidence), nor in the other secondary outcomes that were assessed.There were no eligible studies that compared computerised CTG with no CTG.Comparison of computerised CTG versus traditional CTG showed a significant reduction in perinatal mortality with computerised CTG (RR 0.20, 95% CI 0.04 to 0.88, two studies, 0.9% versus 4.2%, 469 women, moderate quality evidence). However, there was no significant difference identified in potentially preventable deaths (RR 0.23, 95% CI 0.04 to 1.29, two studies, N = 469), though the meta-analysis was underpowered to assess this outcome. There was no significant difference identified in caesarean sections (RR 0.87, 95% CI 0.61 to 1.24, 63% versus 72%, one study, N = 59, low quality evidence), Apgar scores less than seven at five minutes (RR 1.31, 95% CI 0.30 to 5.74, two studies, N = 469, very low quality evidence) or in secondary outcomes.

AUTHORS' CONCLUSIONS

There is no clear evidence that antenatal CTG improves perinatal outcome, but further studies focusing on the use of computerised CTG in specific populations of women with increased risk of complications are warranted.

Factors that increase reactivity during fetal nonstress testing

PURPOSE OF REVIEW

The most common method of antepartum fetal surveillance is the nonstress test (NST). Although it has satisfactory false-negative rates, dubious nonreactive results may challenge the physician. Any method or factor increasing the reactive NST results or shortening the time to attain a reactive test may be considerably useful.

RECENT FINDINGS

Most of the studies have found no effect of maternal glucose administration on fetal heart rate and fetal activity, specificity of NST, time to reactivity and percentage of reactive NST results when compared with the control group. Maternal intake of 70% cocoa or caffeine had stimulating action on the fetal reactivity, and this effect on the fetal heart rate was more marked with high concentrations of cocoa (80%). Studies on maternal positioning during NST had equivocal results. Fetal manipulation has no impact on the NST reactivity. Vibroacoustic and halogen light stimulation may be associated with a reduction in time to reactivity.

SUMMARY

These methods may increase the reactivity during a NST and may facilitate the antenatal fetal surveillance.

Antenatal cardiotocography for fetal assessment

BACKGROUND

Cardiotocography (CTG) is a continuous recording of the fetal heart rate obtained via an ultrasound transducer placed on the mother's abdomen. CTG is widely used in pregnancy as a method of assessing fetal well-being, predominantly in pregnancies with increased risk of complications.

OBJECTIVES

To assess the effectiveness of antenatal CTG (both traditional and computerised assessments) in improving outcomes for mothers and babies during and after pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (9 July 2012) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised trials that compared traditional antenatal CTG with no CTG or CTG results concealed; computerised CTG with no CTG or CTG results concealed; and computerised CTG with traditional CTG.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility, quality and extracted data.

MAIN RESULTS

Six studies (involving 2105 women) are included. Overall, the included studies were not of high quality, and only two had both adequate randomisation sequence generation and allocation concealment. All studies that were able to be included enrolled only women at increased risk of complications.Comparison of traditional CTG versus no CTG showed no significant difference identified in perinatal mortality (risk ratio (RR) 2.05, 95% confidence interval (CI) 0.95 to 4.42, 2.3% versus 1.1%, four studies, N = 1627) or potentially preventable deaths (RR 2.46, 95% CI 0.96 to 6.30, four studies, N = 1627), though the meta-analysis was underpowered to assess this outcome. Similarly, there was no significant difference identified in caesarean sections (RR 1.06, 95% CI 0.88 to 1.28, 19.7% versus 18.5%, three trials, N = 1279) nor in the secondary outcomes that were assessed.There were no eligible studies that compared computerised CTG with no CTG.Comparison of computerised CTG versus traditional CTG showed a significant reduction in perinatal mortality with computerised CTG (RR 0.20, 95% CI 0.04 to 0.88, two studies, 0.9% versus 4.2%, 469 women). However, there was no significant difference identified in potentially preventable deaths (RR 0.23, 95% CI 0.04 to 1.29, two studies, N = 469), though the meta-analysis was underpowered to assess this outcome. There was no significant difference identified in caesarean sections (RR 0.87, 95% CI 0.61 to 1.24, 63% versus 72%, one study, N = 59) or in secondary outcomes.

AUTHORS' CONCLUSIONS

There is no clear evidence that antenatal CTG improves perinatal outcome, but further studies focusing on the use of computerised CTG in specific populations of women with increased risk of complications are warranted.

Antenatal cardiotocography for fetal assessment

BACKGROUND

Cardiotocography (CTG) is a continuous recording of the fetal heart rate obtained via an ultrasound transducer placed on the mother's abdomen. CTG is widely used in pregnancy as a method of assessing fetal well-being, predominantly in pregnancies with increased risk of complications.

OBJECTIVES

To assess the effectiveness of antenatal CTG (both traditional and computerised assessments) in improving outcomes for mothers and babies during and after pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (April 2009).

SELECTION CRITERIA

Randomised and quasi-randomised trials that compared traditional antenatal CTG with no CTG or CTG results concealed; computerised CTG with no CTG or CTG results concealed; and computerised CTG with traditional CTG.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed eligibility, quality and extracted data.

MAIN RESULTS

Six studies (involving 2105 women) are included. Overall, the included studies were not of high quality, and only two had both adequate randomisation sequence generation and allocation concealment. All studies that were able to be included enrolled only women at increased risk of complications.Comparison of traditional CTG versus no CTG showed no significant difference identified in perinatal mortality (risk ratio (RR) 2.05, 95% confidence interval (CI) 0.95 to 4.42, 2.3% versus 1.1%, four studies, N = 1627) or potentially preventable deaths (RR 2.46, 95% CI 0.96 to 6.30, four studies, N = 1627, though the meta-analysis was underpowered to assess this outcome. Similarly, there was no significant difference identified in caesarean sections (RR 1.06, 95% CI 0.88 to 1.28, 19.7% versus 18.5%, three trials, N = 1279) nor in the secondary outcomes that were assessed.There were no eligible studies that compared computerised CTG with no CTG.Comparison of computerised CTG versus traditional CTG showed a significant reduction in perinatal mortality with computerised CTG (RR 0.20, 95% CI 0.04 to 0.88, two studies, 0.9% versus 4.2%, 469 women, graph 3.1.1). However, there was no significant difference identified in potentially preventable deaths (RR 0.23, 95% CI 0.04 to 1.29, two studies, N = 469), though the meta-analysis was underpowered to assess this outcome. There was no significant difference identified in caesarean sections (RR 0.87, 95% CI 0.61 to 1.24, 63% versus 72%, one study, N = 59) or in secondary outcomes.

AUTHORS' CONCLUSIONS

There is no clear evidence that antenatal CTG improves perinatal outcome, but further studies focusing on the use of computerised CTG in specific populations of women with increased risk of complications are warranted.

When it comes to pregnant women sleeping, is left right?

Pregnant women who lie in a supine position may develop syncopal symptoms. However, of those women who become symptomatic, only 2% to 4% have significant aortocaval compression. Even in this small minority of symptomatic women, there is no evidence of fetal compromise. The advice often given to pregnant women to lie on the left side is therefore not relevant. In some women, experiencing a pre-syncopal episode will cause them to avoid lying in the supine position.

The effects of different maternal positions on non-stress test: an experimental study

AIMS AND OBJECTIVES

To determine the effects of different maternal positions on non-stress test results and the preferences of mothers for involving positions.

BACKGROUND

The non-stress test (NST) has become a common tool in diagnosing fetal risks. The major problem encountered in the application of the non-stress test has been obtaining erroneous non-reactive non-stress test results when, indeed, the fetus is healthy and oxygenation is sufficient.

STUDY DESIGN

Experiment design with randomly assigned four positions: supine, left lateral, semi-fowler and sitting up. The sample included 408 women in a university hospital in Turkey. Women were randomly assigned to four groups in equal numbers of 102. Data collection and analysis. Data were collected through two instruments: Demographic and Pregnancy History Form and NST tracing. Main outcome measures were percentage of reactive NST and number of minutes for reactivity in each position.

RESULTS

There were significant (P < 0.05) differences among four groups. Supine position showed the least fetal reactivity. In terms of time to reactivity, there were no statistically significant differences. Qualitative data showed that pregnant women were least comfortable in supine position reporting back pain and shortening of breath.

CONCLUSION

Supine position yields the lowest non-reactivity in tandem with physical discomfort such as back pain and difficulty in breathing.

RELEVANCE TO CLINICAL PRACTICE

Sitting up, semi-fowler and left lateral positions are recommended to be used during the non-stress test. In addition, the preferences of the pregnant women should be determined before the test to minimize discomfort which, when it occurs, may signal physiological alterations experienced during the test.

Maternal position during non-stress test and fetal heart rate patterns

OBJECTIVE

The aim of the study was to determinate whether maternal position during the non-stress test (NST) in different weeks of pregnancy influences fetal heart rate patterns.

MATERIALS AND METHODS

A total of 1055 NST lasting 30 min were performed in 368 autochthonous mothers with low-risk pregnancies. On the basis of maternal position during the test we divided into three groups: reclining, sitting, and walking. The cardiotocographic parameters considered were: number of minutes of reactive NST with minimum length, number of fetal movements, fetal heart rate baseline, number of large accelerations, number of dubious NST, and number of variable decelerations.

RESULTS

Fetal heart rate patterns in low-risk pregnancies were studied using NST in different gestational ages and in different maternal positions. Differences in heart rate were found in relationship to both gestational age and maternal position. The minimum length of NST necessary to record at least three large accelerations was significantly different in relationship to both gestational age and maternal position. The number of fetal movements perceived by the mother was greater in the reclining position than in sitting or walking. Together with the progression of pregnancy, the number of dubious NST decreased in all subgroups, especially in the sitting position. The greatest number of variable decelerations was observed in the reclining position and it was increased with pregnancy progression. The NST duration did not vary greatly in the reclining position, but in the sitting position or during walking, the time taken to record the three large accelerations required to define the trace as reactive, decreased significantly with the progression of pregnancy

CONCLUSIONS

Non-stress test in sitting position or during walking should be encouraged because fetal reactivity is more quickly observed.

Computer analysis of the fetal heart rate

Computer analysis of the fetal heart rate is a technology of the Information Age commercially available for research and clinical practice. Intelligent systems are engineered with algorithms or neural networks designed to simulate expert knowledge. Automated analysis has provided objective, standardized, and reproducible data used to research fetal heart rate responses in the antepartum and intrapartum setting. Perinatal information systems can integrate FHR analysis and data management.

The relationship of maternal position to the results of brief nonstress tests: a randomized clinical trial

OBJECTIVE

This study was undertaken to determine whether maternal posture (left lateral recumbent vs semi-Fowler position) had any effect on nonstress test results when the test was performed for a shortened period (10 minutes).

STUDY DESIGN

In this randomized clinical trial of 108 patients with singleton pregnancies at 32 to 42 weeks' gestation, patients were randomly assigned to a "sitting first" (semi-Fowler position) or a "supine first" (left lateral recumbent position) group at the initial visit. The order of position was alternated at subsequent visits. Ten minutes of fetal heart rate monitoring was performed in each position at each visit. Computer analysis of the nonstress test was used to interpret each 10-minute segment for reactivity. Statistical analyses were performed on the paired nonstress test unit (sitting and supine).

RESULTS

There were no adverse clinical outcomes among the participants. Logistic regression analysis showed that both the sequence of the nonstress test and the position were significant and independent factors related to nonstress test reactivity. Tests performed during the second 10 minutes and tests performed with the patient in the semi-Fowler position were more likely to have reactive results.

CONCLUSION

The semi-Fowler position is a superior position for conducting a nonstress test in a short period. Use of this position could decrease the need for prolonged monitoring, thus leading to a more time-effective evaluation of patients at risk.