Abstracts of Recent Research on Pregnancy Exercise
J Phys Act Health. 2013 May 10. [Epub ahead of print]
Exercise Throughout Pregnancy Does Not Cause Preterm Delivery. A Randomized, Controlled Trial.
Source Social Sciences of Physical Activity and Sports, Technical University of Madrid, Spain.
BACKGROUND: In spite of an extensive knowledge of the physiologic features of exercise during pregnancy, we still lack a comprehensive understanding of the effects of different types, intensities and duration of exercise throughout pregnancy on maternal and fetal well being. The aim of the present study was to examine the influence of an aerobic exercise program throughout pregnancy on gestational age at the moment of delivery.
METHODS: This study was a randomized controlled trial. Three hundred and twenty Caucasian (Spanish) healthy pregnant women with singleton gestation were randomly assigned to either an exercise (n=160) or a control (n=16 0) group. Gestational age (weeks) and other outcomes were measured. The exercise program included 85 sessions (general fitness class, three times/week, 55–60 min/session from weeks 8–10 to weeks 38–39 of pregnancy) .
RESULTS: Two hundred and ninety women were analyzed (exercise group EG, n=138, control group CG, n=152). The mean gestational age did not differ between groups (EG= 39.7± 1.3 vs CG= 39.6±1.1 weeks, p=0.81). Relative to preterm deliveries in EG we found 6 (4.3%) and 11 (7.2 %) in CG, (p=0.73).
CONCLUSIONS: A supervised program of moderate exercise performed throughout pregnancy is not a risk of preterm delivery for heal thy pregnant women.
J Nutr Metab. 2013;2013:285948. doi: 10.1155/2013/285948. Epub 2013 Apr 9.
Potential mechanisms of exercise in gestational diabetes.
Source Department of Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada V6T 1Z3.
Abstract Gestational diabetes mellitus (GDM) is defined as glucose intolerance first diagnosed during pregnancy. This condition shares same array of underlying abnormalities as occurs in diabetes outside of pregnancy, for example, genetic and environmental causes. However, the role of a sedentary lifestyle and/or excess energy intake is more prominent in GDM. Physically active women are less likely to develop GDM and other pregnancy-related diseases. Weight gain in pregnancy causes increased release of adipokines from adipose tissue; many adipokines increase oxidative stress and insulin resistance. Increased intramyocellular lipids also increase cellular oxidative stress with subsequent generation of reactive oxygen species. A well-planned program of exercise is an important component of a healthy lifestyle and, in spite of old myths, is also recommended during pregnancy. This paper briefly reviews the role of adipokines in gestational diabetes and attempts to shed some light on the mechanisms by which exercise can be beneficial as an adjuvant therapy in GDM. In this regard, we discuss the mechanisms by which exercise increases insulin sensitivity, changes adipokine profile levels, and boosts antioxidant mechanisms.
Ethiop J Health Sci. 2013 Mar;23(1):59–64.
Effect of aerobic exercise training on maternal weight gain in pregnancy: a meta-analysis of randomized controlled trials.
Source Biomedical Technology Department, School of Health Technology, Federal University of Technology, Owerri, Imo State, Nigeria. siklam_86@ yahoo.co.uk
BACKGROUND: Weight gains in pregnancy within the recommended guidelines are associated with healthy fetal and maternal outcomes; higher weight gains are associated with fetal macrosomia. This study was a systemic review of randomized controlled trials on the effect of aerobic training on maternal weight in pregnancy.
METHODS: The study data source was publications through May 2012 in the MEDLINE (PubMed) database. The citation lists of randomized controlled trials on the effect of aerobic training and maternal weight were extracted. Data on participants’ characteristics, study quality, population, intervention, treatment outcome (maternal weight gain) were collected and analyzed.
RESULTS: There were 11 randomized controlled studies using body weight (kg) as measure of treatment outcome. A total of 1177 subjects were recruited in the 11 studies. The mean± SD weight gain (kg) for the exercise (11.31± 7.44kg) and control (14.42± 6.60kg) groups; Meta-analysis result indicated significant effect of aerobic training on maternal weight (t= -7.580, p= .000) at p< 0.05.
CONCLUSION: It was concluded that aerobic training is an effective tool in maternal weight gain control in pregnancy. More randomized controlled trials are warranted.
BJOG. 2013 Mar 26. doi: 10.1111/1471–0528.12191. [Epub ahead of print]
Risk of cardiovascular disease after pre-eclampsia and the effect of lifestyle interventions: a literature-based study.
Source Division of Obstetrics and Prenatal Medicine, Department of Obstetrics and Gynaecology, Erasmus MC, Rotterdam, the Netherlands.
OBJECTIVE: This study addresses the following questions. Do cardiovascular risk factors fully explain the odds ratio of cardiovascular risk after pre-eclampsia? What is the effect of lifestyle interventions (exercise, diet, and smoking cessation) after pre-eclampsia on the risk of cardiovascular disease?
DESIGN: Literature-based study.
METHODS: Data for the calculations were taken from studies identified by PubMed searches. First, the differences in cardiovascular risk factors after pre-eclampsia compared with an uncomplicated pregnancy were estimated. Second, the effects of lifestyle interventions on cardiovascular risk were estimated. Validated risk prediction models were used to translate these results into cardiovascular risk.
RESULTS: After correction for known cardiovascular risk factors, the odds ratios of pre-eclampsia for ischaemic heart disease and for stroke are 1.89 (IQR 1.76–1.98) and 1.55 (IQR 1.40–1.71), respectively. After pre-eclampsia, lifestyle interventions on exercise, dietary habits, and smoking cessation decrease cardiovascular risk, with an odds ratio of 0.91 (IQR 0.87–0.96).
Cardiovascular risk factors do not fully explain the risk of cardiovascular disease after pre-eclampsia. The gap between estimated and observed odds ratios may be explained by an additive risk of cardiovascular disease by pre-eclampsia. Furthermore, lifestyle interventions after pre-eclampsia seem to be effective in decreasing cardiovascular risk. Future research is needed to overcome the numerous assumptions we had to make in our calculations.
J Psychosom Obstet Gynaecol. 2013 May 6. [Epub ahead of print]
Influence of a single physical exercise class on mood states of pregnant women.
Abstract The aim of the research was to define the influence of a single physical exercise class on mood states of pregnant women and to establish the socio-demographic and personality predictors of mood changes. The sample was comprised of a total of 109 pregnant women aged 19–37 years. Of the group, 62 women participated in physical exercise for pregnant women (the experimental group) and 47 women participated in traditional childbirth education classes (the control group). Emotional states were assessed with the UWIST Mood Adjective Checklist; personality traits were measured with the NEO-FFI, LOT-R and STAI questionnaires. Socio-demographic data were collected with a survey developed by the authors. A single physical exercise class improved the emotional state of pregnant women significantly more than a traditional childbirth education class. Within the experimental group, a significant improvement of mood was observed in all dimensions, while in the control group only hedonic tone increased. Greater improvements in mood can be expected in a group of women who are younger, less optimistic, and who evaluate their health better but physical fitness worse. As a single session of exercise helps improve the mood of pregnant women, this may be an effective strategy to prevent the deterioration of mood state during pregnancy.
Nurs Health Sci. 2013 May 13. doi: 10.1111/nhs.12057. [Epub ahead of print]
American rural women’s exercise self-efficacy and awareness of exercise benefits and safety during pregnancy.
Source Department of Health & Kinesiology, Georgia Southern University.
Abstract Though the positive link between physical activity and maternal health is well documented, physical activity declines during pregnancy and, internationally, rural mothers are less likely than urban mothers to engage in physical activity. Some evidence suggests that self-efficacy is related to sustained engagement in physical activity. The purpose of this study was to examine self-efficacy, perceived benefits, and knowledge of safe exercise among 88 rural pregnant women in a southeastern region of the United States. Exercise self-efficacy was significantly related to maternal age and gestation. Women over age 26 years, and those in the second and third trimesters, scored significantly higher than younger women or those in the first trimester. Fifty-two percent (n = 46) of participants perceived that activity would decrease energy levels, 37.5% (n = 33) did not know that exercise can decrease the risk of gestational diabetes, and 47.6% (n = 41) were unaware that a mother who is overweight is more likely to have an overweight child. Results confirm a need for education to improve women’s knowledge about health benefits and safety information related to physical activity during pregnancy.
© 2013 Wiley Publishing Asia Pty Ltd.
J Matern Fetal Neonatal Med. 2012 Nov;25(11):2372–6. doi: 10.3109/14767058.2012.696165. Epub 2012 Jun 22.
Exercise during pregnancy reduces the rate of cesarean and instrumental deliveries: results of a randomized controlled trial.
Source Technical University of Madrid (UPM), Madrid, Spain. firstname.lastname@example.org
OBJECTIVE: In this study, the authors assessed the effects of a structured, moderate-intensity exercise program during the entire length of pregnancy on a woman’s method of delivery.
METHODS: A randomized controlled trial was conducted with 290 healthy pregnant Caucasian (Spanish) women with a singleton gestation who were randomly assigned to either an exercise (n = 138) or a control (n = 152) group. Pregnancy outcomes, including the type of delivery, were measured at the end of the pregnancy.
RESULTS: The percentage of cesarean and instrumental deliveries in the exercise group were lower than in the control group (15.9%, n = 22; 11.6%, n = 16 vs. 23%, n = 35; 19.1%, n = 29, respectively; p = 0.03). The overall health status of the newborn as well as other pregnancy outcomes was unaffected.
CONCLUSIONS: Based on these results, a supervised program of moderate-intensity exercise performed throughout pregnancy was associated with a reduction in the rate of cesarean, instrumental deliveries and can be recommended for healthy women in pregnancy.
Med Sci Sports Exerc. 2012 Dec;44(12):2263–9. doi: 10.1249/MSS.0b013e318267ad67.
Exercise in pregnancy: effect on fitness and obstetric outcomes-a randomized trial.
Source Professional Association, Austin, TX, USA. email@example.com
OBJECTIVE: A prospective randomized controlled trial was designed to assess the benefits and possible risks of aerobic exercise during pregnancy, using a fitness regimen based on the 2002 American College of Obstetricians and Gynecologists guidelines for exercise during pregnancy.
METHODS: Inactive women were randomized at 12–14 wk gestation to a group that remained sedentary or to a group that performed moderate aerobic exercise 45–60 min, 4 d·wk, through 36 wk gestation. Thirty-one subjects in each group completed the study.
RESULTS: Compared with women who remained sedentary, active women improved aerobic fitness (P < 0.05) and muscular strength (P < 0.01), delivered comparable size infants with significantly fewer cesarean deliveries (P < 0.01), and recovered faster postpartum (P < 0.05), at least related to the lower incidence of cesarean section. Active women developed no gestational hypertension (P = 0.16 compared with controls) and reported no injuries related to the exercise regimen. In the active group, there was one premature birth at 33 wk by a woman with a history of premature delivery of twins at 34 wk. There were no differences between groups in the incidence of gestational diabetes, musculoskeletal pains during pregnancy, flexibility on sit-and-reach test, mean length of pregnancy, neonatal Apgar scores, placenta weights, overall length of labor, weight gain during pregnancy, or weight retention postpartum.
CONCLUSION: Previously sedentary women who began exercising at 12–14 wk improved fitness and delivery outcomes.
Physical activity before and during pregnancy and risk of gestational diabetes mellitus: a meta-analysis.Tobia DK, Zhang C, van Dam RM, Bowers K, Hu FB. Diabetes Care. 2010 Sep 27.
The researchers concluded that higher levels of physical activity prior to pregnancy or in early pregnancy are associated with a significantly lower risk of developing GDM. The study search identified 7 pre-pregnancy and 5 early pregnancy studies, including 5 prospective cohorts, 2 retrospective case-controls, and 2 cross-sectional study designs. Pre-pregnancy physical activity was assessed in 34,929 total participants including 2,813 GDM cases, giving a pooled odds ratio of 0.45 (95% CI: 0.28–0.75) when comparing the highest vs. lowest categories. Exercise in early pregnancy was assessed in 4,401 total participants including 361 GDM cases, and was also significantly protective (OR=0.76, 95%CI: 0.70, 0.83).
Aerobic exercise during pregnancy improves health-related quality of life: a randomised trial. Montoya Arizabaleta AV et al. J Physiother. 2010;56(4):253–8.
The researchers concluded that a supervised 3-month program of primarily aerobic exercise during pregnancy improves health-related quality of life. The experimental group had improved their health-related quality of life more than the control group in the physical component summary of the questionnaire by 6 points, the physical function domain by 7 points, the bodily pain domain by 7 points and the general health domain by 5 points.
The experimental group completed a 3-month supervised exercise program, commencing at 16 to 20 weeks of gestation. Each session included walking (10 min), aerobic exercise (30 min), stretching (10 min), and relaxation (10 min). The control group continued usual activities and performed no specific exercise. The primary outcome was health-related quality of life assessed by the Colombian version of the Medical Outcome Study Short-Form Health Survey at baseline and immediately after the 3-month intervention.
Effects of Yoga:
For more than 30 years, DTP has included exercise components that are elements of yoga (centering, deep breathing, mindfulness/transcendence, isometrics and relaxation), because these are measurable, effective components within a total fitness package. Cardiovascular conditioning is our centerpiece — along with specific strength work — since these produce most of the benefits of prenatal fitness. Due to the growing popularity of prenatal yoga at the expense of cardiovascular conditioning and strength training, we have been seeking credible research evidence about yoga’s effect on pregnancy, birth and recovery.
Despite the length of time it has been available, there is little data to establish yoga’s efficacy beyond reducing some discomforts and perhaps improving body trust, often through the use of positions, breathing skills and mindfulness that are also common childbirth preparation and comfort measures. The relaxation element — achievable through any standard alpha brain wave producing method — can help promote promote progress in early labor, as the Relaxation Response (per Benson) is known to help the body release oxytocin in early labor (per Odent). However, the only study of the correlation among labor onset, yoga and the length of the first stage was very small. It was performed in Thailand and we cannot find any record of exactly what was performed during the six sessions over the course of pregnancy.
Yoga during pregnancy: effects on maternal comfort, labor pain and birth outcomes. Chuntharapat S, et al. Complement Ther Clin Pract. 2008 May;14(2):105–15. Epub 2008 Mar 4.
This study examined the effects of a yoga program on maternal comfort, labor pain, and birth outcomes. 74-primigravid Thai women were randomized. The yoga program involved six, 1-h sessions at prescribed weeks of gestation. A variety of instruments were used to assess maternal comfort, labor pain and birth outcomes. The experimental group was found to have a shorter duration of the first stage of labor. No differences were found, between the groups, regarding pethidine usage, labor augmentation or newborn Apgar scores at 1 and 5 min.
We also found a small, non-randomized study that indicated chronic practice of yoga produces similar affects.
Effects of a prenatal yoga programme on the discomforts of pregnancy and maternal childbirth self-efficacy in Taiwan. Sun YC, et al. Midwifery. 2010 Dec;26(6):e31-6. Epub 2009 Feb 25.
This non-randomized study aimed to provide yoga to primigravidas in the third trimester of pregnancy to decrease discomforts associated with pregnancy and increase childbirth self-efficacy. Low risk, sedentary primigravidas were targeted. The program was 12–14 weeks, with at least three sessions per week. Each workout lasted for 30 minutes. Program participants reported significantly fewer pregnancy discomforts than the control group (38.28 vs 43.26, z=-2.58, p=0.01) at 38–40 weeks of gestation and exhibited higher outcome and self-efficacy expectancies during the active stage of labour (104.13 vs 83.53, t=3.24, p=0.002; 99.26 vs 77.70, t=3.99, p ? 0.001) and the second stage of labour (113.33 vs 88.42, t=3.33, p=0.002; 102.19 vs 79.40, t=3.71, p ? 0.001) compared with the control group. Interestingly, the researchers concluded that the provision of booklets and videos on yoga during pregnancy may contribute to a reduction in pregnancy discomforts and improved childbirth self-efficacy.
Efficacy of yoga on pregnancy outcome. Narendran S, et al. J Altern Complement Med. 2005 Apr;11(2):237–44.
The only matched-control study we have seen that reports any beneficial outcomes for yoga participants vs. controls was a small study conducted in India. Women participated daily in supervised 1-hour sessions, while controls walked. The daily yoga participants’ outcomes were improved compared with controls, including a reduction in IUGR, in conjunction with infection and PIH. It is important to keep in mind that these outcomes occurred in a setting where under-weight, over-work and infection-related complications are common.
It is interesting to note that aerobic fitness provides the same benefits as those seen in these studies, while also reducing the need for augmentation or other interventions, as well as reducing the risk of fetal distress.
During the second stage of labor, the transition to an ergotropic reflex promotes the release of oxytocin as the body changes from a parasympathetic state in the first stage to a sympathetic state in the second stage (that is why we call the end of the first stage transition). The physiology of pushing requires a very aggressive approach. Our in-house data suggest that we have found a balance for helping women develop the necessary traits to accomplish both the passive state required by the first stage and the endurance capacity to become aggressive during expulsion. We measure this in the reduction of our cesarean rate by 1/2 to 1/3 compared to the local population.
There is evidence of inverse risk for cesarean as the amount and intensity of aerobic conditioning increases. These studies are also fairly small, although they are numerous and have produced consistent results concerning dose-effect. There is growing interest within the health care field that supporting prenatal aerobics could help reduce the cesarean rate. There is no information from any credible sources concerning the relationship of yoga to type of birth. The only available statistical information is the coincidental correlation that as the cesarean rate has risen in the U.S., so has the population that participates in prenatal yoga.
Yoga remains an illusive subject of study. So much depends on who is teaching and what they are teaching. Unlike aerobics, strength, range of motion, relaxation response, balance, coordination and training specificity — all of which we can prescribe and measure — the popular term yoga has lost meaning. How much of exactly what is necessary to produce effects? What are those effects? Are they beneficial? These questions are yet to be answered.