Victoria L Meah

Cardiac output and related haemodynamics during pregnancy: a series of meta-analyses

Objective Cardiac output, a fundamental parameter of cardiovascular function, has consistently been shown to increase across healthy pregnancy; however, the time course and magnitude of adaptation remains equivocal within published literature. The aim of the present meta-analyses was to comprehensively describe the pattern of change in cardiac output during healthy pregnancy. Method A series of meta-analyses of previously published cardiac output data during healthy, singleton pregnancies was completed. PubMed and Scopus databases were searched for studies published between 1996 and 2014. Included studies reported absolute values during a predetermined gestational age (non-pregnant, late first trimester, early and late second trimester, early and late third trimester, early and late postpartum). Cardiac output was measured through echocardiography, impedance cardiography or inert gas rebreathing. Observational data were meta-analysed at each gestational age using a random-effects model. If reported, related haemodynamic variables were evaluated. Results In total, 39 studies were eligible for inclusion, with pooled sample sizes ranging from 259 to 748. Cardiac output increased during pregnancy reaching its peak in the early third trimester, 1.5 L/min (31%) above non-pregnant values. The observed results from this study indicated a non-linear rise to this point. In the early postpartum, cardiac output had returned to non-pregnant values. Conclusion The present results suggest that cardiac output peaks in the early third trimester, following a non-linear pattern of adaptation; however, this must be confirmed using longitudinal studies. The findings provide new insight into the normal progression of cardiac output during pregnancy.

Prenatal exercise is not associated with fetal mortality: a systematic review and meta-analysis

Objective To perform a systematic review of the relationship between prenatal exercise and fetal or newborn death. Design Systematic review with random-effects meta-analysis and meta-regression. Data sources Online databases were searched up to 6 January 2017. Study eligibility criteria Studies of all designs were included (except case studies) if they were published in English, Spanish or French and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone [“exercise-only”] or in combination with other intervention components [eg, dietary; “exercise + co-intervention”]), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcome (miscarriage or perinatal mortality). Results Forty-six studies (n=2 66 778) were included. There was ‘very low’ quality evidence suggesting no increased odds of miscarriage (23 studies, n=7125 women; OR 0.88, 95% CI 0.63 to 1.21, I2=0%) or perinatal mortality (13 studies, n=6837 women, OR 0.86, 95% CI 0.49 to 1.52, I2=0%) in pregnant women who exercised compared with those who did not. Stratification by subgroups did not affect odds of miscarriage or perinatal mortality. The meta-regressions identified no associations between volume, intensity or frequency of exercise and fetal or newborn death. As the majority of included studies examined the impact of moderate intensity exercise to a maximum duration of 60 min, we cannot comment on the effect of longer periods of exercise. Summary/conclusions Although the evidence in this field is of ‘very low’ quality, it suggests that prenatal exercise is not associated with increased odds of miscarriage or perinatal mortality. In plain terms, this suggests that generally speaking exercise is ‘safe’ with respect to miscarriage and perinatal mortality.

Effects of prenatal exercise on fetal heart rate, umbilical and uterine blood flow: a systematic review and meta-analysis

Objective To perform a systematic review and meta-analysis examining the influence of acute and chronic prenatal exercise on fetal heart rate (FHR) and umbilical and uterine blood flow metrics. Design Systematic review with random-effects meta-analysis and meta-regression. Data sources Online databases were searched up to 6 January 2017. Study eligibility criteria Studies of all designs were included (except case studies) if published in English, Spanish or French, and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone [“exercise-only”] or in combination with other intervention components [eg, dietary; “exercise + co-intervention”]), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcomes (FHR, beats per minute (bpm); uterine and umbilical blood flow metrics (systolic:diastolic (S/D) ratio; Pulsatility Index (PI); Resistance Index (RI); blood flow, mL/min; and blood velocity, cm/s)). Results ‘Very low’ to ‘moderate’ quality evidence from 91 unique studies (n=4641 women) were included. Overall, FHR increased during (mean difference (MD)=6.35bpm; 95% CI 2.30 to 10.41, I2=95%, p=0.002) and following acute exercise (MD=4.05; 95% CI 2.98 to 5.12, I2=83%, p<0.00001). The incidence of fetal bradycardia was low at rest and unchanged with acute exercise. There were no significant changes in umbilical or uterine S/D, PI, RI, blood flow or blood velocity during or following acute exercise sessions. Chronic exercise decreased resting FHR and the umbilical artery S/D, PI and RI at rest. Conclusion Acute and chronic prenatal exercise do not adversely impact FHR or uteroplacental blood flow metrics.

Exercise for the prevention and treatment of low back, pelvic girdle and lumbopelvic pain during pregnancy: a systematic review and meta-analysis

Objective The purpose of this review was to investigate the relationship between prenatal exercise, and low back (LBP), pelvic girdle (PGP) and lumbopelvic (LBPP) pain. Design Systematic review with random effects meta-analysis and meta-regression. Data sources Online databases were searched up to 6 January 2017. Study eligibility criteria Studies of all designs were eligible (except case studies and reviews) if they were published in English, Spanish or French, and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone [“exercise-only”] or in combination with other intervention components [eg, dietary; “exercise + co-intervention”]), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcome (prevalence and symptom severity of LBP, PGP and LBPP). Results The analyses included data from 32 studies (n=52 297 pregnant women). ‘Very low’ to ‘moderate’ quality evidence from 13 randomised controlled trials (RCTs) showed prenatal exercise did not reduce the odds of suffering from LBP, PGP and LBPP either in pregnancy or the postpartum period. However, ‘very low’ to ‘moderate’ quality evidence from 15 RCTs identified lower pain severity during pregnancy and the early postpartum period in women who exercised during pregnancy (standardised mean difference −1.03, 95% CI −1.58, –0.48) compared with those who did not exercise. These findings were supported by ‘very low’ quality evidence from other study designs. Conclusion Compared with not exercising, prenatal exercise decreased the severity of LBP, PGP or LBPP during and following pregnancy but did not decrease the odds of any of these conditions at any time point.

MATERNAL CARDIAC TWIST PRE-PREGNANCY: POTENTIAL AS A NOVEL MARKER OF PRE-ECLAMPSIA

This article was published in Fetal and Maternal Medicine Review on 13 December 2013 (online), available at http://dx.doi.org/10.1017/S0965539513000156

Glucose responses to acute and chronic exercise during pregnancy: a systematic review and meta-analysis

Objective To perform a systematic review and meta-analysis to explore the relationship between prenatal exercise and glycaemic control. Design Systematic review with random-effects meta-analysis and meta-regression. Data sources Online databases were searched up to 6 January 2017. Study eligibility criteria Studies of all designs were included (except case studies and reviews) if they were published in English, Spanish or French, and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of acute or chronic exercise, alone (‘exercise-only’) or in combination with other intervention components (eg, dietary; ‘exercise+cointervention’) at any stage of pregnancy), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcome (glycaemic control). Results A total of 58 studies (n=8699) were included. There was ‘very low’ quality evidence showing that an acute bout of exercise was associated with a decrease in maternal blood glucose from before to during exercise (6 studies, n=123; mean difference (MD) −0.94 mmol/L, 95% CI −1.18 to −0.70, I2=41%) and following exercise (n=333; MD −0.57 mmol/L, 95% CI −0.72 to −0.41, I2=72%). Subgroup analysis showed that there were larger decreases in blood glucose following acute exercise in women with diabetes (n=26; MD −1.42, 95% CI −1.69 to −1.16, I2=8%) compared with those without diabetes (n=285; MD −0.46, 95% CI −0.60 to −0.32, I2=62%). Finally, chronic exercise-only interventions reduced fasting blood glucose compared with no exercise postintervention in women with diabetes (2 studies, n=70; MD −2.76, 95% CI −3.18 to −2.34, I2=52%; ‘low’ quality of evidence), but not in those without diabetes (9 studies, n=2174; MD −0.05, 95% CI −0.16 to 0.05, I2=79%). Conclusion Acute and chronic prenatal exercise reduced maternal circulating blood glucose concentrations, with a larger effect in women with diabetes.

Effects of prenatal exercise on incidence of congenital anomalies and hyperthermia: a systematic review and meta-analysis

Objective To investigate the relationships between exercise and incidence of congenital anomalies and hyperthermia. Design Systematic review with random-effects meta-analysis . Data sources Online databases were searched from inception up to 6 January 2017. Study eligibility criteria Studies of all designs were eligible (except case studies and reviews) if they were published in English, Spanish or French, and contained information on population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone [“exercise-only”] or in combination with other intervention components [e.g., dietary; “exercise + co-intervention”]), comparator (no exercise or different frequency, intensity, duration, volume or type of exercise) and outcome (maternal temperature and fetal anomalies). Results This systematic review and meta-analysis included ‘very low’ quality evidence from 14 studies (n=78 735) reporting on prenatal exercise and the odds of congenital anomalies, and ‘very low’ to ‘low’ quality evidence from 15 studies (n=447) reporting on maternal temperature response to prenatal exercise. Prenatal exercise did not increase the odds of congenital anomalies (OR 1.23, 95% CI 0.77 to 1.95, I2=0%). A small but significant increase in maternal temperature was observed from pre-exercise to both during and immediately after exercise (during: 0.26°C, 95% CI 0.12 to 0.40, I2=70%; following: 0.24°C, 95% CI 0.17 to 0.31, I2=47%). Summary/Conclusions These data suggest that moderate-to-vigorous prenatal exercise does not induce hyperthermia or increase the odds of congenital anomalies. However, exercise responses were investigated in most studies after 12 weeks’ gestation when the risk of de novo congenital anomalies is negligible.

Effectiveness of exercise interventions in the prevention of excessive gestational weight gain and postpartum weight retention: a systematic review and meta-analysis

Objective Gestational weight gain (GWG) has been identified as a critical modifier of maternal and fetal health. This systematic review and meta-analysis aimed to examine the relationship between prenatal exercise, GWG and postpartum weight retention (PPWR). Design Systematic review with random effects meta-analysis and meta-regression. Online databases were searched up to 6 January 2017. Study eligibility criteria Studies of all designs in English, Spanish or French were eligible (except case studies and reviews) if they contained information on the population (pregnant women without contraindication to exercise), intervention (frequency, intensity, duration, volume or type of exercise, alone [“exercise-only”] or in combination with other intervention components [eg, dietary; “exercise + co-intervention”]), comparator (no exercise or different frequency, intensity, duration, volume or type of exercise) and outcomes (GWG, excessive GWG (EGWG), inadequate GWG (IGWG) or PPWR). Results Eighty-four unique studies (n=21 530) were included. ‘Low’ to ‘moderate’ quality evidence from randomised controlled trials (RCTs) showed that exercise-only interventions decreased total GWG (n=5819; −0.9 kg, 95% CI −1.23 to –0.57 kg, I2=52%) and PPWR (n=420; −0.92 kg, 95% CI −1.84 to 0.00 kg, I2=0%) and reduced the odds of EGWG (n=3519; OR 0.68, 95% CI 0.57 to 0.80, I2=12%) compared with no exercise. ‘High’ quality evidence indicated higher odds of IGWG with prenatal exercise-only (n=1628; OR 1.32, 95% CI 1.04 to 1.67, I2=0%) compared with no exercise. Conclusions Prenatal exercise reduced the odds of EGWG and PPWR but increased the risk of IGWG. However, the latter result should be interpreted with caution because it was based on a limited number of studies (five RCTs).

Functional hemodynamic testing in pregnancy: recommendations of the International Working Group on Maternal Hemodynamics

In the general population, functional hemodynamic testing, such as that during submaximal aerobic exercise and isometric handgrip, and the cold pressor test, has long been utilized to unmask abnormalities in cardiovascular function. During pregnancy, functional hemodynamic testing places additional demands on an already stressed maternal cardiovascular system. Dysfunctional responses to such tests in early pregnancy may predict the development of hypertensive disorders that develop later in gestation. For each of the above functional hemodynamic tests, these recommendations provide a description of the test, test protocol and equipment required, and an overview of the current understanding of clinical application during pregnancy. Copyright

Combined neonatal therapies for cardiac function in adulthood – live together, die alone?

The healthy development of a fetus and the continued health of a newborn child are of primary interest to all beings. Unfortunately, pregnancy does not always progress favourably and can result in premature birth. Preterm infants are at high risk of complications in the neonatal period, such as chronic lung disease, and may develop cardiorespiratory problems in later life. As a consequence, different therapeutic strategies have been developed to improve the cardiorespiratory health of neonates. One popular choice is the use of glucocorticoid therapy, such as dexamethasone, because it reduces the relatively high prevalence of chronic lung disease in prematurely born offspring. However, negative side-effects of neonatal dexamethasone therapies are also known. For instance, the beneficial short-term effects of glucocorticoid therapy are accompanied by a variety of severe long-term cardiovascular complications, including pathological cardiac and vascular remodelling, hypertension, renal damage and insulin resistance (for specific references see Niu et al. 2013). These negative cardiovascular outcomes highlight the need for alternative therapies that achieve improved maturation of the respiratory system and alleviation of acute inflammatory symptoms associated with neonatal chronic lung disease, as well as maintained survival of the offspring into adulthood. To date, little is known about neonatal therapies that achieve these ambitious aims.