Effect of maternal position and uterine activity on periodic maternal heart rate changes before elective cesarean section at term

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.

A Novel, Cardiac-Derived Algorithm for Uterine Activity Monitoring in a Wearable Remote Device

Background: Uterine activity (UA) monitoring is an essential element of pregnancy management. The gold-standard intrauterine pressure catheter (IUPC) is invasive and requires ruptured membranes, while the standard-of-care, external tocodynamometry (TOCO)’s accuracy is hampered by obesity, maternal movements, and belt positioning. There is an urgent need to develop telehealth tools enabling patients to remotely access care. Here, we describe and demonstrate a novel algorithm enabling remote, non-invasive detection and monitoring of UA by analyzing the modulation of the maternal electrocardiographic and phonocardiographic signals. The algorithm was designed and implemented as part of a wireless, FDA-cleared device designed for remote pregnancy monitoring. Two separate prospective, comparative, open-label, multi-center studies were conducted to test this algorithm.

Methods: In the intrapartum study, 41 laboring women were simultaneously monitored with IUPC and the remote pregnancy monitoring device. Ten patients were also monitored with TOCO. In the antepartum study, 147 pregnant women were simultaneously monitored with TOCO and the remote pregnancy monitoring device.

Results: In the intrapartum study, the remote pregnancy monitoring device and TOCO had sensitivities of 89.8 and 38.5%, respectively, and false discovery rates (FDRs) of 8.6 and 1.9%, respectively. In the antepartum study, a direct comparison of the remote pregnancy monitoring device to TOCO yielded a sensitivity of 94% and FDR of 31.1%. This high FDR is likely related to the low sensitivity of TOCO.

Conclusion: UA monitoring via the new algorithm embedded in the remote pregnancy monitoring device is accurate and reliable and more precise than TOCO standard of care. Together with the previously reported remote fetal heart rate monitoring capabilities, this novel method for UA detection expands the remote pregnancy monitoring device’s capabilities to include surveillance, such as non-stress tests, greatly benefiting women and providers seeking telehealth solutions for pregnancy care.

Effect of positioning on blood pressure measurement in pregnancy

Blood pressure is the key vital sign to detecting hypertensive disorders in pregnancy. The importance of taking blood pressure properly was recently underscored by the publication of updated ACC/AHA guidelines for measuring blood pressure in patients. However, the recommended position of seating with arms and back supported is not always feasible to achieve clinically, especially for inpatient women who are pregnant. Therefore, it is clinically important to understand the effects of alternative patient positioning on blood pressure measurements. We conducted a review of studies which considered patient position on the effect of blood pressure in pregnancy. This review demonstrates that clinically significant differences may occur based on patient positioning. Despite the small number of primary studies that include pregnant women, notable reductions in blood pressure measurements have been observed in the left lateral recumbent position, a common position during labor or during monitoring, in comparison to measurements taken in the supported seated position. Ultimately, these differences could affect the clinical management of patients and care should be taken to document and consider the position in which the reading was taken.

Impact of physical activity on course and outcome of pregnancy from pre- to postnatal

A healthy lifestyle that includes physical activity has numerous positive effects on the mother and child during and after pregnancy. In this context physical activity plays a central role due to its influence on body composition. While visceral fatty tissue has a pro-inflammatory effect via so-called adipokines, myokines seem to have a more anti-inflammatory effect and thus prevent numerous diseases such as gestational hypertension or gestational diabetes. However, many women show a decreased level of physical activity during pregnancy when compared to pre-gestation levels. The reasons underlying this change are manifold and include concern about the effects of physical exertion on the unborn child. Gynaecologists and midwives are also often uncertain about what specific advice to give regarding physical activity. The present review describes, besides the underlying mechanisms, current physical activity recommendations and corresponding evidence with a focus on weight development in terms of obesity, gestational diabetes and foetal outcome.

Effects of maternal sleep position on fetal and maternal heart rate patterns using overnight home fetal ECG recordings

OBJECTIVE

To assess the effects of maternal position on maternal and fetal heart rate and heart rate variability (HRV) in healthy late gestation pregnancies using non-invasive techniques during overnight studies.

METHODS

In an observational study of women between 34 and 36 weeks of pregnancy conducted from September 1, 2013, to March 31, 2014, at Columbia University Medical Center, New York, US, maternal and fetal ECG recordings and position monitoring were undertaken through the night in the woman's own home. These data were used for time domain analyses of fetal and maternal heart rate and HRV.

RESULTS

Forty-two women were recruited to the study which showed that maternal position affected maternal heart rate (MHR), with left side sleeping associated with lower heart rate (left vs right P=0.017, left vs supine P=0.027) and higher overall HRV (left vs right P=0.032). MHR showed significant overnight changes (P=0.032). No significant positional or overnight effects were observed in fetal heart rate patterns.

CONCLUSION

This study uniquely incorporated analyses on maternal and fetal physiology and extended the knowledge of effects of maternal overnight sleep position on MHR in the natural sleep environment.

Effects of low maternal heart rate on fetal growth and birthweight

OBJECTIVE

To evaluate the association between birthweight and maternal heart rate (MHR) or heart rate variability (HRV) under resting conditions at 20-24 gestational weeks and 34 weeks or later (34+ weeks).

METHODS

Data were retrospectively reviewed from the Safe Passage Study, a prospective longitudinal cohort study of alcohol use in pregnancy and birth outcomes in Cape Town, South Africa, between August 2007 and January 2015. Using custom-designed software, MHR and indicators of HRV were obtained from the recorded maternal electrocardiograms and compared with birthweight and z-scores of birthweight adjusted for gestation and gender.

RESULTS

Data from 5655 women were included. MHR increased from 84.6 bpm at 20-24 weeks to 88.3 bpm at 34+ weeks. Increasing MHR from 70-80 to 80-90 and 90-100 bpm at 20-24 weeks was associated with increasing birthweight from 2940 to 2998 and 3032 g, respectively (P<0.05). MHR and HRV contributed 29% to the variability associated with birthweight, whereas maternal body mass index at recruitment contributed 44%. Similar associations were observed for MHR at 34+ weeks.

CONCLUSION

The observed association of low maternal heart rate with birthweight might help to identify pregnancies at risk of poor fetal growth.

Maternal heart rate patterns under resting conditions in late pregnancy

Objectives:

To describe maternal heart rate patterns observed during antenatal monitoring under resting conditions between the gestational ages of 34 to 38 weeks and to demonstrate its associations with uterine activity.

Methods:

Each participant had five high quality ECG electrodes attached to her anterior abdominal wall which were connected to the Monica AN24 device to collect raw electrical signals from the maternal and fetal ECG and signals of uterine activity. Proprietary software was then used to download the raw data and extract the maternal and fetal heart rate patterns and uterine activity.

Results:

Several distinct maternal heart rate patterns were observed. These included unusually high or low levels of variability, tachycardia, bradycardia, regular and irregular periodic changes and sporadic changes where the heart rate suddenly decreased or increased. Some of the fluctuations, especially decelerations of maternal heart rate, seemed to be associated with uterine activity.

Conclusion:

The clinical implications of these different patterns, for both the mother and fetus, needs to be explored further. There is a need for computerized analyses of the different maternal patterns during different gestational ages to determine its relevance.

Synopsis

Various maternal heart rate patterns under resting conditions in late pregnancy are described.