Possible beneficial effect of exercise, by reducing oxidative stress, on the incidence of preeclampsia

Leisure-time physical activity is associated with reduced risks of breast cancer and triple negative breast cancer in Nigerian women

BACKGROUND

Leisure-time physical activity(LTPA) is associated with a reduced risk of breast cancer, but this has less been investigated by cancer subtypes in Africans living in Sub-Saharan Africa(SSA). We examined the associations between LTPA and breast cancer including its subtypes in Nigerian women and explored the effect modification of body size on such associations.

METHODS

The sample included 508 newly diagnosed primary invasive breast cancer cases and 892 controls from the Nigerian Integrative Epidemiology of Breast Cancer(NIBBLE) Study. Immunohistochemical(IHC) analysis was available for 294 cases. Total metabolic equivalents(METs) per hour/week of LTPA were calculated and divided by quartiles(Q1 <3.75, Q2:3.75-6.69, Q3:6.70-14.74, Q4:14.75 ≤). We applied logistic regressions to estimate the adjusted Odds Ratios(ORs) between LTPA and breast cancer and by its molecular subtypes and whether age-adjusted associations are modified by BMI.

RESULTS

The mean age(Mean±SD) of cases vs. controls(45.5 ± 11.1vs.40.1 ± 9.0) was higher, and the mean total METs hour/week was higher in controls vs. cases(11.9 ± 14.9vs.8.3 ± 11.1,p-value<0.001). Overall, 43.2%(N = 127/294) were classified as HRP, and 41.8%(N = 123/294) as TNBC. Women in the higher LTPA quartiles(Q3-Q4) vs. Q1 had lower odds of having breast cancer(OR_Q4vs.Q1=0.51,95%CI:0.35-0.74) and TNBC(OR_Q4vs.Q1=0.51, 95%CI:0.27-0.96), but not HRP(OR_Q4vs.Q1=0.61,95%CI:0.34-1.09) after adjusting for age, age at first menarche, body size, breastfeeding, menopausal, parity, contraceptives, demographics, alcohol, smoking, and physical activity at home and work. Lastly, LTPA and its age-adjusted association with breast cancer was more pronounced in women with BMI< 30 vs. BMI 30 + .

CONCLUSIONS

LTPA may reduce the risk of breast cancer, especially TNBC, which is the more aggressive and prevalent molecular subtype of breast cancer in SSA.

Influence of Prenatal Aerobic Exercise on Fetal Morphometry

OBJECTIVE

The purpose of this study was to determine the effects of supervised prenatal aerobic exercise on fetal morphometrics at 36 weeks of gestation.

METHODS

This study used data from a, 24-week, two-arm randomized controlled trial: aerobic exercise (EX) and stretching/breathing comparison group (CON). Singleton pregnancies (< 16 weeks pregnant) and women aged 18 to 40 years, BMI between 18.5 and 34.99 kg/m², and no preexisting chronic health conditions were eligible. The EX group participated in 150 min of moderate-intensity weekly exercise while CON group participated in low-intensity stretching/breathing. Fetal morphometric outcomes included estimated fetal weight (EFW), ponderal index (PI), abdominal circumference (AC), anterior abdominal wall thickness (AAWT), fat mass, percent body fat, fat-free mass, assessed at 36 weeks gestation. Partial spearman rank correlations were performed, adjusting for 3^rd trimester weight gain.

RESULTS

Of the 128 pregnant women randomized, 83 (EX [n = 46] and CON [n = 37]) were eligible for analyses. Intention-to-treat analysis showed no differences in EFW (rho_s = - 0.13; p = 0.28), PI (rho_s = 0.03; p = 0.81), AC (rho_s = - 0.22; p = 0.09), AAWT (rho_s = - 0.11; p = 0.40), fat mass (rho_s = - 0.16; p = 0.23), percent body fat (rho_s = - 0.10; p = 0.43), and fat-free mass (rho_s = - 0.22; p = 0.08), after adjusting for 3rd trimester weight gain. Similar results were observed in the per protocol analyses.

CONCLUSIONS

For Practice Moderate-intensity aerobic exercise during pregnancy was not associated with select fetal morphometrics at 36 weeks gestation. Potential differences in offspring morphometrics may only appear in the postnatal period, as previously documented. Further research into offspring tissue composition after birth is encouraged, specifically studies investigating differences in cellular signaling pathways related to adipose and skeletal muscle tissue development.

Oxidative stress and mitochondrial dysfunction in early-onset and late-onset preeclampsia

Preeclampsia is a pregnancy-specific syndrome with multisystem involvement which leads to foetal, neonatal, and maternal morbidity and mortality. This syndrome is characterized by the onset of clinical signs and symptoms and delivery before (early-onset preeclampsia, eoPE), or after (late-onset preeclampsia, loPE), the 34 weeks of gestation. Preeclampsia is a mitochondrial disorder where its differential involvement in eoPE and loPE is unclear. Mitochondria regulate cell metabolism and are a significant source of reactive oxygen species (ROS). The syncytiotrophoblast in eoPE and loPE show altered mitochondrial structure and function resulting in ROS overproduction, oxidative stress, and cell damage and death. Mitochondrial dysfunction in eoPE may result from altered expression of several molecules, including dynamin-related protein 1 and mitofusins, compared with loPE where these factors are either reduced or unaltered. Equally, mitochondrial fusion/fission dynamics seem differentially modulated in eoPE and loPE. It is unclear whether the electron transport chain and oxidative phosphorylation are differentially altered in these two subgroups of preeclampsia. However, the activity of complex IV (cytochrome c oxidase) and the expression of essential proteins involved in the electron transport chain are reduced, leading to lower oxidative phosphorylation and mitochondrial respiration in the preeclamptic placenta. Interventional studies in patients with preeclampsia using the coenzyme Q₁₀, a key molecule in the electron transport chain, suggest that agents that increase the antioxidative capacity of the placenta may be protective against preeclampsia development. In this review, the mitochondrial dysfunction in both eoPE and loPE is summarized. Therapeutic approaches are discussed in the context of contributing to the understanding of mitochondrial dysfunction in eoPE and loPE.

Cardiovascular Considerations in Caring for Pregnant Patients: A Scientific Statement From the American Heart Association

Cardio-obstetrics has emerged as an important multidisciplinary field that requires a team approach to the management of cardiovascular disease during pregnancy. Cardiac conditions during pregnancy include hypertensive disorders, hypercholesterolemia, myocardial infarction, cardiomyopathies, arrhythmias, valvular disease, thromboembolic disease, aortic disease, and cerebrovascular diseases. Cardiovascular disease is the primary cause of pregnancy-related mortality in the United States. Advancing maternal age and preexisting comorbid conditions have contributed to the increased rates of maternal mortality. Preconception counseling by the multidisciplinary cardio-obstetrics team is essential for women with preexistent cardiac conditions or history of preeclampsia. Early involvement of the cardio-obstetrics team is critical to prevent maternal morbidity and mortality during the length of the pregnancy and 1 year postpartum. A general understanding of cardiovascular disease during pregnancy should be a core knowledge area for all cardiovascular and primary care clinicians. This scientific statement provides an overview of the diagnosis and management of cardiovascular disease during pregnancy.

The Mechanisms and Effects of Physical Activity on Breast Cancer

Breast cancer is the most common cancer in women. An extensive part of this health problem can be prevented by an active lifestyle. Physical activity can reduce the risk of breast cancer, reduce the rate of recurrence, and increase the survival rate of patients with breast cancer. The aim of this review was to summarize our current knowledge regarding the effects of physical activity on breast cancer risk, recurrence, and survival. Furthermore, we investigated 5 possible underlying mechanisms through which physical activity has an influence on breast cancer (ie, a reduction of sex hormones, metabolic hormones, adipokines and oxidative stress, and an improvement of the immune function). In this review, we give a complete overview of this subject.

Physical activity and the risk of preeclampsia: a systematic review and meta-analysis

BACKGROUND

Physical activity has been hypothesized to reduce the risk of preeclampsia, but epidemiologic studies have not shown consistent results. Therefore, we conducted a systematic review and dose-response meta-analysis of epidemiologic studies.

METHODS

PubMed, Embase, and Ovid databases were searched for case-control and cohort studies of physical activity and preeclampsia up to 2 November 2012. We estimated summary relative risks (RRs) using a random effects model.

RESULTS

Fifteen studies were included. The summary RR for high versus low prepregnancy physical activity was 0.65 (95% confidence interval [CI] = 0.47-0.89, I = 0%; n = 5). In the dose-response analysis, the summary RR was 0.72 (0.53-0.99; I = 0%; n = 3) per 1 hour per day and 0.78 (0.63-0.96; I = 0%; n = 2) per 20 metabolic equivalent task (MET)-hours per week. The summary RR for high versus low physical activity in early pregnancy was 0.79 (0.70-0.91; I = 0%; n = 11). In the dose-response analysis, the summary RR per 1 hour per day was 0.83 (0.72-0.95; I = 21%; n = 7) and 0.85 (0.68-1.07; I = 69%; n = 3) per 20 MET-hours per week. A nonlinear association was observed for physical activity before pregnancy and risk of preeclampsia (test for nonlinearity, P = 0.03), but not for physical activity in early pregnancy (test for nonlinearity, P = 0.37), with a flattening of the curve at higher levels of activity. Both walking and greater intensity of physical activity were inversely associated with preeclampsia.

CONCLUSIONS

Our analysis suggests a reduced risk of preeclampsia with increasing levels of physical activity before pregnancy and during early pregnancy.

Impaired renal function and increased urinary isoprostane excretion in Ghanaian women with pre-eclampsia

Background

The cause of pre-eclampsia remains largely unknown, but oxidative stress (an imbalance favoring oxidant over antioxidant forces) has been implicated in contributing to the clinical symptoms of hypertension and proteinuria. Assessment of oxidative stress in pre-eclampsia using urinary isoprostane has produced conflicting results, and it is likely that renal function may affect isoprostane excretion. The aim of this study was to determine the role of oxidative stress in the pathophysiology of pre-eclampsia and to assess the effect of renal function on isoprostane excretion in pre-eclampsia in the Ghanaian population.

Methods

This was a case-controlled study, comprising 103 pre-eclamptic women and 107 normal pregnant controls and conducted at the Korle-Bu Teaching Hospital between December 2006 and May 2007. The study participants were enrolled in the study after meeting the inclusion criteria and signing their written informed consent. Oxidative stress was determined by measuring urinary excretion of isoprostane and total antioxidant capacity using an enzyme-linked immunosorbent assay technique. Renal function was assessed by calculating the estimated glomerular filtration rate using the Modification of Diet in Renal Disease formula.

Results

The pre-eclampsia group had significantly (P = 0.0006) higher urinary isoprostane excretion (2.81 ± 0.14 ng/mg creatinine) than the control group (2.01 ± 0.18 ng/mg creatinine) and a significantly (P = 0.0008) lower total antioxidant power (1.68 ± 0.05 mM) than the control group (1.89 ± 0.04 mM). Urinary isoprostane excretion showed a positive correlation with both mean arterial pressure (r = 0.261) and microalbuminuria (r = 0.510) in the pre-eclampsia cases. The pre-eclampsia group had a significantly lower estimated glomerular filtration rate than the control group (P < 0.001), indicating more renal impairment.

Conclusion

The increased urinary excretion of isoprostanes and decreased total antioxidant power in the in pre-eclampsia group suggest increased production of oxidants and depletion and/or reduction of maternal antioxidants. Increased oxidative stress may be important in the pathophysiology of pre-eclampsia by contributing to endothelial dysfunction, proteinuria, and hypertension.

Prenatal exercise research

In this review of recent research on prenatal exercise, studies from several different countries suggest that only approximately 40% of pregnant women exercise, even though about 92% are encouraged by their physicians to exercise, albeit with some 69% of the women being advised to limit their exercise. A moderate exercise regime reputedly increases infant birthweight to within the normal range, but only if exercise is decreased in late pregnancy. Lower intensity exercise such as water aerobics has decreased low back pain more than land-based physical exercise. Heart rate and blood pressure have been lower following yoga than walking, and complications like pregnancy-induced hypertension with associated intrauterine growth retardation and prematurity have been less frequent following yoga. No studies could be found on tai chi with pregnant women even though balance and the risk of falling are great concerns during pregnancy, and tai chi is one of the most effective forms of exercise for balance. Potential underlying mechanisms for exercise effects are that stimulating pressure receptors during exercise increases vagal activity which, in turn, decreases cortisol, increases serotonin and decreases substance P, leading to decreased pain. Decreased cortisol is particularly important inasmuch as cortisol negatively affects immune function and is a significant predictor of prematurity. Larger, more controlled trials are needed before recommendations can be made about the type and amount of pregnancy exercise.

Prenatal stretching exercise and autonomic responses: preliminary data and a model for reducing preeclampsia

PURPOSE

Preeclampsia is a leading cause of perinatal mortality and morbidity, and it increases maternal risk for future cardiovascular disease. The purpose of the study was to explore the relationships among stretching exercise, autonomic cardiac response, and the development of preeclampsia.

DESIGN

Secondary data analysis.

METHODS

Heart rate and pulse pressure were longitudinally examined in this secondary data analysis among women who engaged in stretching exercise daily from 18 weeks of gestation to the end of pregnancy compared with women who did walking exercise daily during the same time period. A total of 124 women were randomized to either stretching (n=60) or walking (n=64) in the parent study.

FINDINGS

Heart rates in the stretching group were consistently lower than those in the walking group.

CONCLUSIONS

Based on the results of this secondary data analyses, a physiologic framework for possible beneficial effects of stretching exercise by enhancing autonomic responses on reducing risks for preeclampsia is proposed and discussed.

CLINICAL RELEVANCE

If the protective effect is established, stretching exercise can be translated into nursing intervention for prenatal care.

Increased capillary vascularity in the femur of aged rats by exercise training

During aging, bone loss occurs in association with alteration of blood perfusion in the tissue. A number of studies have shown that repaired blood perfusion in various organs was improved by regular exercise, but the effect of exercise on bone microcirculation has not been studied fully yet. This study aimed to investigate the effect of exercise training on capillary vascularity in rat femur by directly observing the bone microcirculation under a laser scanning confocal microscope. Male Wistar rats were divided into three groups: sedentary-young (aged 4-6 months), sedentary-aged (aged 20-22 months) and trained-aged (aged 20-22 months). The exercise program included swimming training 5 days/week for 8 weeks. Using our newly devised window chamber, we directly observed the femur microcirculation of each group under a laser scanning confocal microscopic system. Based on the fluorescent image of microvasculature recorded at the surface of the femur, bone capillary vascularity (CV) was measured using computer software. Liver malondialdehyde (MDA) level was also measured to examine the relationship between CV and oxidative stress in aged rats. In the sedentary-aged group, the CV significantly decreased, but the MDA level significantly increased, compared with sedentary-young group. In the trained-aged group, CV was significantly higher, whereas the MDA level was significantly lower, compared with the sedentary-aged group. In both sedentary-young and sedentary-aged rats, the CV was linearly correlated with the MDA level. In conclusion, the swimming exercise could attenuate aged-induced suppression of CV, closely related to exercise-ameliorated oxidative stress in aged.

Adherence to walking or stretching, and risk of preeclampsia in sedentary pregnant women

Pregnant women at risk for preeclampsia may benefit from the positive effects of exercise, but they may be unlikely to adhere to an exercise program. A randomized trial was conducted with 124 sedentary pregnant women to compare the effects of walking exercise to a stretching exercise on adherence and on the preeclampsia risk factors of heart rate (HR), blood pressure, and weight gain. Walkers exercised less than stretchers both overall and as pregnancy advanced. HR and blood pressure were lower among stretchers than walkers, but weight gain did not differ between the groups. For sedentary pregnant women, a stretching exercise may be more effective than walking in mitigating the risk of preeclampsia due to higher adherence and possible cardiac-physiologic effects.

Overview of current state of research on pregnancy outcomes in minority populations

Pregnancy outcomes improved significantly over the 20th century in the United States but currently vary widely between women of different ethnic and racial backgrounds. The current health disparities that exist are based, in part, only on differences in socioeconomic status or education. There is wide variability in pregnancy outcomes within specific subgroups of women. Disparities may be due to underlying differences in health before pregnancy, differences in community norms, and individual lifestyle choices and to differences in health care delivery systems. Areas for needed research and promising new models of care are reviewed.

Clinical physiology of exercise in pregnancy: a literature review

OBJECTIVES

To review the existing literature on the physiology of exercise in pregnancy as a basis for clinical practice guidelines for prenatal exercise prescription.

METHODS

MEDLINE search for English language abstracts and articles published between 1966 and 2003 related to physiological adaptations to pregnancy, effects of pregnancy on responses to acute exercise and aerobic conditioning, effects of acute maternal exercise on indexes of fetal well-being, impact of physical conditioning on birth weight and other pregnancy outcomes, and use of exercise to prevent or treat gestational diabetes mellitus and preeclampsia.

RESULTS

Maximal aerobic power (VO(2)max, L/min) is well-preserved in pregnant women who remain physically active, but anaerobic working capacity may be reduced in late gestation. The increase in resting heart rate, reduction in maximal heart rate, and resulting smaller heart rate reserve render heart rate a less precise way of estimating exercise intensity. As rating of perceived exertion (RPE) is not altered by pregnancy, the use of revised pulse rate target zones along with Borg's RPE scale is recommended to prescribe exercise intensity during pregnancy. Responses to prolonged submaximal exercise (>30 min) in late gestation include a moderate reduction in maternal blood glucose concentration, which may transiently reduce fetal glucose availability. The normal response to sustained submaximal exercise is an increase in fetal heart rate (FHR) baseline. Transient reductions in FHR reactivity, fetal breathing movements, and FHR variability may also occur in association with more strenuous exercise. Controlled prospective studies have demonstrated that moderate prenatal exercise during the second and third trimesters is useful to improve aerobic fitness and maternal-fetal physiological reserve without affecting fetal growth.

CONCLUSIONS

The Physical Activity Readiness Medical Examination for Pregnancy is recommended for use by physicians and midwives to provide medical clearance for prenatal exercise. Evidence-based prenatal exercise guidelines are needed to counsel healthy and fit pregnant women on the safety of involvement in more strenuous physical conditioning. Future study is also recommended to determine the usefulness of prenatal exercise in the prevention and treatment of gestational diabetes mellitus and preeclampsia.