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

[Review of nutrition and hydration in relation to physical exercise during pregnancy]

Introduction

Studies on nutritional recommendations for pregnant women who exercise are scarce. The objective of this article is not to focus on the diet of pregnant women as a whole, but to review those aspects of it that may be related to physical exercise. To this end, the nutritional and hydration recommendations contained in the main clinical practice guides on physical exercise during pregnancy are collected, including the first Spanish guides. Likewise, the energy requirements required by pregnant women who perform physical exercise during pregnancy for adequate gestational weight gain are addressed, aspects related to macronutrients in the aforementioned population group, and two specific topics, such as nutritional needs in the adolescent who practices physical exercise during pregnancy and eating disorders in pregnant athletes It is concluded by stating that pregnant women who exercise regularly should eat a varied and balanced diet, such as the Mediterranean diet, avoid long periods of fasting to avoid the appearance of hypoglycemia and maintain adequate fluid intake before, during and after physical exercise. Pregnant adolescents who engage in physical exercise require nutritional supervision to achieve adequate gestational weight gain. The pregnant athlete with an eating disorder has a higher risk of complications during pregnancy and childbirth, gynecological, fetal and neonatal, and, therefore, requires close monitoring by specialists in maternal-fetal medicine.

Physical Activity during Pregnancy and Risk of Gestational Diabetes Mellitus: A Meta-Review

BACKGROUND

Nowadays, pregnant women require more individualized attention in their assistance process during pregnancy. One of the aspects that requires the most focus is the suitability of carrying out physical activity. The objective of this meta-review is to find out the effects of physical activity during pregnancy on the incidence of GDM compared to women who do not perform physical activity.

METHODS

A search was conducted in Cochrane, CSIC, Ebscohost, Proquest, Pubmed, Scielo, and Scopus. The search focused on systematic reviews and meta-analyses published in the last five years. The AMSTAR-2 scale was used as a quality assessment tool for the final sample.

RESULTS

A total of 18 systematic reviews and meta-analyses were included. Sixteen of them found out that physical activity during pregnancy has preventive effects for GDM compared with women who lacked physical activity. Among the studies, we found a reduction in the risk of GDM of between 24% and 38% and odds ratios ranging between 0.39 and 0.83 calculated for a 95% CI. Only two studies did not find statistically significant effects. Other variables such as type and duration of physical activity, overweight and obesity, gestational age, etc., were also considered.

CONCLUSIONS

Physical activity prevents the incidence of GDM. The main characteristics that enhance this preventive effect are starting at the initial stages of pregnancy and maintaining during the whole pregnancy as well as combining strength and aerobic exercise at a low to moderate intensity.

Quality of life in women with normal pregnancy

Pregnancy affects a woman's physiological and psychological state. One of the most important aspects that requires attention is the quality of life of pregnant women. The quality of life of women during this period is influenced by a number of factors, such as back and pelvic pain, physiotherapy and physical activity, and also sexual satisfaction. Eighty-five women aged 21-40 years (30.80 ± 5.05) in pregnancy trimesters participated in the study: 17 women were in the first trimester, 32 women were in the second, and 36 women in the third trimester. The World Health Organisation Quality of Life (WHOQOL-BREF), Oswestry Disability Index (ODI) and the Sexual Satisfaction Scale for Women SSS-W-R15 were used to answer the research hypotheses. Respondents also provided information on questions regarding physiotherapy treatments and physical activity. Quality of life (WHOQOL-BREF) and disability due to back pain (ODI) showed a statistical association and relationship (p-value = 0.045, rho = - 0.22). Quality of life (WHOQOL-BREF) has an association with sexual satisfaction in pregnant women (SSS-W-R15) (p-value = 0.003, rho = 0.32). The trimester of pregnancy has an effect on ODI (p-value = 0.027). A significant effect occurred in a detailed comparison between the first and third trimesters of pregnancy (p-value = 0.026). The trimester also has an impact on quality of life (WHOQOL-BREF) (p-value = 0.002). In a detailed analysis, a significant effect occurred between the first and third trimesters of pregnancy (p-value = 0.001). Moreover, the trimester of pregnancy has an impact on sexual satisfaction (SSS-W-R15) (p-value = 0.027). After detailed statistical analysis, a significant effect occurred between trimesters one and three of pregnancy (p-value = 0.046). On the other hand, the number of days of physical activity performed by pregnant women per month and the type of physical activity had no effect on the ODI (p-value = 0.071). The type of physical activity performed by pregnant women also has no effect on ODI (p-value = 0.023). The number of physiotherapy treatments used has no effect on the ODI (p-value = 0.156). Type of physiotherapy treatment has no effect on ODI (p-value = 0.620). Normal pregnancy quality of life (WHOQOL) is related to ODI and sexual satisfaction (SSS-W-R15), while the trimester of pregnancy also has an impact on quality of life, disability due to back pain and sexual satisfaction.

Diagnosis to Delivery: A Randomized Clinical Trial of Postmeal Walking in Women with Gestational Diabetes

PURPOSE

The aim of this study was to determine whether advice to perform postmeal walking could be an effective and feasible alternate to standard care continuous walking for the management of gestational diabetes (GDM).

METHODS

Forty women with GDM were randomized between 28 and 30 wk of gestation into either standard care (CTL; 30-min continuous walking, most days per week) or standard care with advice to PMW (daily 10-min walks after three main meals) for ~7 wk. The primary outcome for this randomized controlled trial was postprandial glucose assessed by continuous glucose monitors. Continuous glucose monitor and ActivPAL inclinometers (physical activity parameters) were each worn for 7 d at ~28 and ~35 wk gestation. Delivery outcomes were also collected. A linear mixed model compared the changes across time between groups.

RESULTS

Twenty-six women (PMW: n = 12, CTL: n = 14; age 34 ± 5 y) completed the trial. Mean 3 h postprandial glucose at dinner was higher in the PMW versus CTL group at baseline and across the intervention (main effect group, P = 0.04). Twenty-four hours, nocturnal, and fasting glucose were similar between groups. The PMW group spent ~57 min·d -1 more time sedentary and ~11 min·d -1 less time stepping versus CTL (main effect group: P = 0.02 and 0.05). Adherence to the prescribed 30 min·d -1 of physical activity was high, regardless of whether accumulated as 3 × 10-min or one single bout of walking.

CONCLUSIONS

Distributing activity as 10-min bouts after main meals did not improve postprandial glucose outcomes compared with standard-care control. More research on the optimal duration and intensity of postmeal walks to improve postprandial responses are needed. Strategies that mitigate sedentary time and increase the minutes of physical activity accumulated across the day in pregnancy are also warranted.

Behavior reallocations within 24-h movement profiles and change in cardiometabolic biomarkers during pregnancy

OBJECTIVE

The goal of this study was to investigate associations of reallocations within 24-h movement profiles and changes in cardiometabolic biomarkers from early to late pregnancy.

METHODS

In 137 individuals with prepregnancy overweight/obesity, waking movement was measured using wrist-worn accelerometers, sleep was self-reported, and biomarkers were measured in fasting serum samples at 12 and 32 weeks' gestation. We used compositional isotemporal substitution models.

RESULTS

On average, biomarkers increased 21%-83% across pregnancy. For those with guideline-recommended moderate/vigorous-intensity physical activity (MVPA) in early pregnancy, reallocating 30 min from MVPA to sleep, sedentary behavior, or light-intensity physical activity (LPA) was associated with a 0.6 mmol/L greater increase in total cholesterol (95% CI: -0.1 to 1.2) and a 0.7 mmol/L greater increase in low-density lipoprotein (LDL) cholesterol (95% CI: 0.1 to 1.3) from early to late pregnancy. For those with low MVPA in early pregnancy, reallocating 30 min from sleep, sedentary behavior, or LPA to MVPA was associated with a 0.6 mmol/L lower increase in total cholesterol (95% CI: -1.3 to 0.1) and a 0.8 mmol/L lower increase in LDL cholesterol (95% CI: -1.4 to -0.1) from early to late pregnancy. There were no associations with change in glucose, insulin, homeostatic model assessment for insulin resistance, very low-density lipoprotein, or high-density lipoprotein cholesterol, triglycerides, or free fatty acids.

CONCLUSIONS

Maintaining or achieving a 24-h movement profile with guideline-recommended amounts of MVPA may be beneficial for reducing pregnancy-induced increases in total and LDL cholesterol.

A narrative review of exercise dose during pregnancy

The current recommendations for prenatal exercise dose align with those from the American College of Sports Medicine; 150 min of moderate intensity every week of pregnancy. However, recent works suggest there may be a dose-dependent beneficial effect for mother and offspring; maternal and offspring health outcomes respond differently to low, medium, and high doses of prenatal exercise. It is, therefore, our aim to summarize the published evidence (years 1950-2023) for five metrics of prenatal exercise training commonly reported, that is, "FITT-V": Frequency (number of sessions), Intensity (metabolic equivalents "METs"), Time (duration of sessions), Type (exercise mode), Volume (exercise MET*mins). The target audience includes clinicians and health care professionals, as well as exercise professionals and physiologists. Data suggest that moderate exercise frequency (3-4 times weekly) appears safe and efficacious for mother and offspring, while there is contradictory evidence for the safety and further benefit of increased frequency beyond 5 sessions per week. Moderate (3-6 METs) and vigorous (>6 METs) intensity prenatal exercise have been shown to promote maternal and offspring health, while little research has been performed on low-intensity (<3 METs) exercise. Exercise sessions lasting less than 1 hr are safe for mother and fetus, while longer-duration exercise should be carefully considered and monitored. Taken together, aerobic, resistance, or a combination of exercise types is well tolerated at medium-to-high volumes and offers a variety of type-specific benefits. Still, research is needed to define (1) the "minimum" effective dose of exercise for mother and offspring health, as well as (2) the maximum tolerable dose from which more benefits may be seen. Additionally, there is a lack of randomized controlled trials addressing exercise doses during the three trimesters of pregnancy. Further, the protocols adopted in research studies should be more standardized and tested for efficacy in different populations of gravid women.

Physical activity and sedentary time across pregnancy and associations with neonatal weight, adiposity and cord blood parameters: a secondary analysis of the DALI study

BACKGROUND/OBJECTIVES

Obesity during pregnancy is associated with neonatal adiposity, which is a risk factor for childhood obesity. Maternal physical activity (PA) and sedentary behaviours during pregnancy might modify this risk. We therefore studied associations between maternal PA and sedentary time (ST) during pregnancy and neonatal anthropometry and cord blood parameters and investigated whether associations differed by offspring sex.

SUBJECTS/METHODS

Participants of the Vitamin D And Lifestyle Intervention for Gestational Diabetes Mellitus Prevention (DALI) study with a BMI  ≥ 29 kg/m2 were analysed as a cohort. Maternal moderate-to-vigorous PA (MVPA) and ST were measured repeatedly with accelerometers across pregnancy. Associations between mean levels and changes in MVPA and ST and birthweight, neonatal adiposity (fat mass (FM)%) and cord blood parameters, including C-peptide, leptin and lipids, were analysed in 213 mother-child pairs with Bayesian multilevel models. Interactions with offspring sex were considered.

RESULTS

Almost all women decreased MVPA levels and increased ST throughout gestation. Both higher maternal mean MVPA and increasing MVPA were associated with lower offspring FM% in males (-0.520%; 95% CI: -1.011%, -0.031% and -4.649%; -7.876%, -1.432% respectively). In female offspring, mean ST was associated with lower cord blood C-peptide (-0.145 µg/l; -0.279 µg/l, -0.005 µg/l). No associations were found with birthweight or other cord blood parameters.

CONCLUSIONS

Maternal MVPA is associated with neonatal fat mass, but not birthweight, in male offspring. Our findings underline the importance of physical activity throughout pregnancy.

It's time to increase physical activity promotion among pregnant women in France

BACKGROUND

The lockdown linked to COVID-19 was shown to have negative effects on healthy behaviors in the general population, prompting the implementation of adapted public health measures. However, more vulnerable populations, such as pregnant women, were not specifically taken into account. At the time of writing this study, we know little about how the COVID-19 pandemic impacted the physical activity (PA) behavior of pregnant women in France. Given the many reports in the literature about women's low level of PA throughout pregnancy and the negative effects of the COVID-19 lockdown on behaviors in the general population; however, we might assume that their sedentary behaviors increased. The current study aimed to analyze the French recommendations and PA promotion among pregnant women.

MATERIALS AND METHODS

A literature search was done using PubMed for the key terms "physical activity/physical activity promotion," "pregnant women/pregnancy,", and "French population/France." All the relevant studies were included to support the argument for this narrative review.

RESULTS

Efforts to promote PA for pregnant women often seem ineffective and even unrealistic, and many women become overweight or obese during pregnancy. Health professionals need evidence-based guidelines and continuous training and skills development in order to convincingly encourage women to be more active during pregnancy and the postpartum period.

CONCLUSION

Health policies should strengthen PA promotion among pregnant women with detailed evidence-based guidelines on PA during postpartum.

A culturally tailored personaliseD nutrition intErvention in South ASIan women at risk of Gestational Diabetes Mellitus (DESI-GDM): a randomised controlled trial protocol

INTRODUCTION

South Asians are more likely to develop gestational diabetes mellitus (GDM) than white Europeans. Diet and lifestyle modifications may prevent GDM and reduce undesirable outcomes in both the mother and offspring. Our study seeks to evaluate the effectiveness and participant acceptability of a culturally tailored, personalised nutrition intervention on the glucose area under the curve (AUC) after a 2-hour 75 g oral glucose tolerance test (OGTT) in pregnant women of South Asian ancestry with GDM risk factors.

METHODS AND ANALYSIS

A total of 190 South Asian pregnant women with at least 2 of the following GDM risk factors-prepregnancy body mass index>23, age>29, poor-quality diet, family history of type 2 diabetes in a first-degree relative or GDM in a previous pregnancy will be enrolled during gestational weeks 12-18, and randomly assigned in a 1:1 ratio to: (1) usual care, plus weekly text messages to encourage walking and paper handouts or (2) a personalised nutrition plan developed and delivered by a culturally congruent dietitian and health coach; and FitBit to track steps. The intervention lasts 6-16 weeks, depending on week of recruitment. The primary outcome is the glucose AUC from a three-sample 75 g OGTT 24-28 weeks' gestation. The secondary outcome is GDM diagnosis, based on Born-in-Bradford criteria (fasting glucose>5.2 mmol/L or 2 hours post load>7.2 mmol/L).

ETHICS AND DISSEMINATION

The study has been approved by the Hamilton Integrated Research Ethics Board (HiREB #10942). Findings will be disseminated among academics and policy-makers through scientific publications along with community-orientated strategies.

TRIAL REGISTRATION NUMBER

NCT03607799.

Optimizing Blood Glucose Control through the Timing of Exercise in Pregnant Individuals Diagnosed with Gestational Diabetes Mellitus

This study aimed to evaluate the effectiveness of moderate intensity walking on postprandial blood glucose control for pregnant individuals with (GDM) and without gestational diabetes mellitus (NON-GDM). Using a randomized cross-over design, individuals completed 5 days of exercise (three 10-min walks immediately after eating (SHORT), or one 30-min walk (LONG) outside of 1 h after eating). These protocols were preceded and separated by 2-days of habitual exercise (NORMAL). Individuals were instrumented with a continuous glucose monitor, a physical activity monitor for 14-days, and a heart rate monitor during exercise. Participants completed a physical activity enjoyment scale (PACES) to indicate their protocol preference. The GDM group had higher fasting, 24-h mean, and daily peak glucose values compared to NON-GDMs across all conditions (effect of group, p = 0.02; p = 0.02; p = 0.03, respectively). Fasting, 24-h mean, and daily peak glucose were not influenced by the SHORT or LONG exercise (effect of intervention, p > 0.05). Blood glucose values were higher among the GDM group for at least 1 h after eating, yet the exercise intervention had no effect on 1 or 2 h postprandial glucose values (effect of intervention, p > 0.05). Physical activity outcomes (wear time, total activity time, and time spent on each intensity) were not different between the groups nor interventions (effect of group, p > 0.05; effect of intervention, p > 0.05,). There were no differences between the groups or interventions for the PACES score (effect of group, p > 0.05; effect of intervention, p > 0.05). To conclude, there were no differences between the groups or exercise protocols on blood glucose control. More research is warranted to elucidate higher exercise volumes in this outcome for individuals with GDM.

The Influence of Exercise-Associated Small Extracellular Vesicles on Trophoblasts In Vitro

Exercise induces the release of small extracellular vesicles (sEVs) into circulation that are postulated to mediate tissue cross-talk during exercise. We previously reported that pregnant individuals released greater levels of sEVs into circulation after exercise compared to matched non-pregnant controls, but their biological functions remain unknown. In this study, sEVs isolated from the plasma of healthy pregnant and non-pregnant participants after a single bout of moderate-intensity exercise were evaluated for their impact on trophoblasts in vitro. Exercise-associated sEVs were found localized within the cytoplasm of BeWo choriocarcinoma cells, used to model trophoblasts in vitro. Exposure to exercise-associated sEVs did not significantly alter BeWo cell proliferation, gene expression of angiogenic growth factors VEGF and PLGF, or the release of the hormone human chorionic gonadotropin. The results from this pilot study support that exercise-associated sEVs could interact with trophoblasts in vitro, and warrant further investigation to reveal their potential role in communicating the effects of exercise to the maternal–fetal interface.

Prenatal Exercise and Cardiovascular Health (PEACH) study: impact of meal timing and pre-exercise blood glucose values on glycemic responses to acute exercise in pregnancy

We retrospectively analyzed data from 28 participants engaging in moderate-intensity aerobic exercise (265 sessions; 25-40 min) between 18-34 weeks gestation (NCT02948439). The mean change in blood glucose (BG) from pre- to post-acute exercise session was -1.0 ± 1.2 mmol/L. Pre-exercise BG significantly predicted the change in BG (p < 0.001), even when controlling for meal timing, exercise duration, and gestational age. Hypoglycemia only occurred in 3% of sessions. Therefore, in healthy pregnancy the change in BG during exercise is small and primarily related to pre-exercise BG values.

Activity Restriction and Hospitalization in Pregnancy: Can Bed-Rest Exercise Prevent Deconditioning? A Narrative Review

Evidence suggests that exercise during pregnancy is beneficial to both parent and fetus. However, there are high-risk pregnancy conditions that may warrant hospitalization. In our narrative review, we first describe the clinical implications for activity restriction in pregnancy, the effects of hospitalization, and the impact of bed rest on non-pregnant individuals. We provide examples of a 30 min bed-rest exercise program for hospitalized pregnant patients using the principal of suggested frequency, intensity, time (duration) of activity, and type of activity (FITT) using a resistance tool while in bed. If the individual is able to ambulate, we recommend short walks around the ward. Every minute counts and activity should be incorporated into a program at least 3 times per week, or every day if possible. As in all exercise programs, motivation and accountability are essential. Flexibility in timing of the exercise intervention is important due to the scheduling of medical assessments that may occur throughout the day for these hospitalized patients. Evidence suggests that by improving physical and emotional health through a bed-rest exercise program during a hospitalized pregnancy may help the individual resume demanding daily activity in the postpartum period and improve quality of life once birth has occurred. More research is necessary to improve the health of those individuals who are hospitalized during pregnancy, with follow up and support into the postpartum period.

The short-term effect of a mHealth intervention on gestational weight gain and health behaviors: The SmartMoms Canada pilot study

Gestational weight gain (GWG) has been shown to impact several maternal-infant outcomes. Since healthcare provider guidance on weight gain and healthy behaviors alone has failed to help women to meet guidelines during pregnancy, a practical adjunctive approach is to deliver evidence-based behavior change programs through mobile interventions. The present study aimed to assess the short-term effect of the SmartMoms Canada app to promote adequate GWG and healthy behaviors. Twenty-nine pregnant women were recruited in this app-based intervention trial to test whether a higher app usage (≥ 3.8 min·week^-1) between 12-20 gestational weeks and 24-28 gestational weeks improved GWG, diet, physical activity, and sleep, compared to women with a lower app usage (< 3.8 min·week^-1). Two-way mixed ANOVA for repeated measures was used to estimate the effect of the app usage and time, as well as their interaction on GWG and healthy behaviors. The likelihood ratio was used to examine the association between app usage categorization and GWG classification. Cramer's V statistic was used to estimate the effect size for interpretation of the association. Pregnant women using the SmartMoms Canada app more frequently had a higher moderate-to-vigorous physical activity (MVPA) daily average when compared with women with a lower usage (mean difference: 17.84 min/day, 95% CI: 2.44; 33.25). A moderate effect size (28.6% vs. 15.4%; Cramer's V = 0.212) was found for the association between app categorization and rate of GWG, representing a greater adherence to the GWG guidelines in women in the higher app usage group vs. the lower app usage group. Considering other physical activity, diet, and sleep variables, no app categorization effect was observed. A short-term higher usage of SmartMoms Canada app has a positive effect on objectively-measured MVPA.

Glycemic response to acute high-intensity interval versus moderate-intensity continuous exercise during pregnancy

The present study investigated the glycemic response to an acute high-intensity interval training (HIIT) session (10 one-minute intervals ≥90% HRmax interspersed with one-minute of active recovery) versus a moderate-intensity continuous training (MICT) session (30 min at 64%-76% HRmax ) during pregnancy. Twenty-four normoglycemic females with a singleton pregnancy (27.8 ± 4.7 weeks of gestation, 31.5 ± 4.1 years of age, body mass index: 25.2 ± 11.3) participated in a randomized crossover design study. A flash glucose monitor and accelerometer were worn continuously for 7 days recording glycemic response, physical activity, and sleep. Nutritional intake and enjoyment of the exercise were self-reported. Average heart rate during exercise was higher for HIIT (82 ± 4% HRmax ) compared with MICT (74 ± 4% HRmax ; p < 0.001) and participants achieved a peak heart rate of 92 ± 3% during HIIT (range 85%-97% HRmax ) compared with 81 ± 4% during MICT (p < 0.001). The change in glucose values from pre-to-postexercise were not different between conditions (HIIT: -0.62 ± 1.00 mmol/L; MICT: -0.81 ± 1.05 mmol/L; p = 0.300) with the exception that fewer individuals experienced postexercise hypoglycemia immediately following HIIT compared with MICT (8% versus 33% respectively; p = 0.041). Other glucose variables was not different between exercise protocols. Physical activity (p = 0.07) and caloric intake did not differ (p = 0.10). The majority of participants preferred HIIT (87.5%) and had greater perceived enjoyment compared to MICT (HIIT: 7.8 ± 1.5; MICT: 6.6 ± 2.0; p = 0.015). Sleep duration was 52 ± 73 min longer after participating in HIIT compared with the night prior (main effect for time p = 0.017); no significant changes for MICT. Overall, an acute session of HIIT appears to be well tolerated and demonstrates no adverse effects on maternal glycemic response.

Development of the Get Active Questionnaire for Pregnancy: Breaking down barriers to prenatal exercise

Evidence-based guidelines represent the highest level of scientific evidence to identify best-practices for clinical/public health. However, the availability of guidelines do not guarantee their use, targeted knowledge translation strategies and tools are necessary to help promote uptake. Following publication of the 2019 Canadian Guideline for Physical Activity throughout Pregnancy, the Get Active Questionnaire for Pregnancy, and an associated Health Care Provider Consultation Form for Prenatal Physical Activity were developed to promote guideline adoption and use amongst pregnant individuals and health care providers. This paper describes the process of developing these tools. First, a survey was administered to qualified exercise professionals to identify the barriers and facilitators in using existing prenatal exercise screening tools. A Working Group of researchers and stakeholders then convened to develop an evidence-informed exercise pre-participation screening tool for pregnant individuals, building from previous tool and survey findings. Finally, end-user feedback was solicited through a survey and key informant interviews to ensure tools are feasible and acceptable to use in practice. The uptake and use of these documents by pregnant individuals, exercise and health care professionals will be assessed in future studies. Novelty Bullets • Evidence supports the safety/benefits of exercise for most pregnant individuals; however, exercise is not recommended for a small number of individuals with specific medical conditions. • The Get Active Questionnaire for Pregnancy and Health Care Provider Consultation Form for Physical Activity during Pregnancy identify individuals where prenatal exercise may pose a risk, while reducing barriers to physical activity participation for the majority of pregnant individuals.

Physical exercise in pregnancy: benefits, risks and prescription

OBJECTIVES

The aim of this article is to provide a comprehensive literature review, gathering the strongest evidence about the risks and benefits and the prescription of physical exercise during pregnancy.

CONTENT

Regular physical exercise during pregnancy is associated with numerous benefits. In general women are not adequately advised on this matter. Along with their concerns regarding the potential associated risks, it contributes to the abandonment or refusal to start exercising during pregnancy. A systematic review was conducted in MEDLINE including articles considered to have the highest level of scientific evidence. Fifty-seven articles, including 32 meta-analysis, 9 systematic reviews and 16 randomized controlled trials were included in the final literature review.

SUMMARY

Exercise can help preventing relevant pregnancy related disorders, such as gestational diabetes, excessive gestational weight gain, hypertensive disorders, urinary incontinence, fetal macrosomia, lumbopelvic pain, anxiety and prenatal depression. Exercise is not related with an increased risk of maternal or perinatal adverse outcomes. Compliance with current guidelines is sufficient to achieve the main benefits, and exercise type and intensity should be based on woman's previous fitness level.

OUTLOOK

Exercise in pregnancy is safe for both mother and fetus, contributing to prevent pregnancy related disorders. Exercise type and intensity should be adapted to woman's previous fitness level, medical history and characteristics of the ongoing pregnancy.

A prospective study of the relationships between movement and glycemic control during day and night in pregnancy

Both disturbed sleep and lack of exercise can disrupt metabolism in pregnancy. Accelerometery was used to objectively assess movement during waking (physical activity) and movement during sleeping (sleep disturbance) periods and evaluated relationships with continuous blood glucose variation during pregnancy. Data was analysed prospectively. 15-women without pre-existing diabetes mellitus wore continuous glucose monitors and triaxial accelerometers from February through June 2018 in Sweden. The relationships between physical activity and sleep disturbance with blood glucose rate of change were assessed. An interaction term was fitted to determine difference in the relationship between movement and glucose variation, conditional on waking/sleeping. Total movement was inversely related to glucose rate of change (p < 0.001, 95% CI (− 0.037, − 0.026)). Stratified analyses showed total physical activity was inversely related to glucose rate of change (p < 0.001, 95% CI (− 0.040, − 0.028)), whereas sleep disturbance was not related to glucose rate of change (p = 0.07, 95% CI (< − 0.001, 0.013)). The interaction term was positively related to glucose rate of change (p < 0.001, 95% CI (0.029, 0.047)). This study provides temporal evidence of a relationship between total movement and glycemic control in pregnancy, which is conditional on time of day. Movement is beneficially related with glycemic control while awake, but not during sleep.

A Technology-Based Pregnancy Health and Wellness Intervention (Two Happy Hearts): Case Study

BACKGROUND

The physical and emotional well-being of women is critical for healthy pregnancy and birth outcomes. The Two Happy Hearts intervention is a personalized mind-body program coached by community health workers that includes monitoring and reflecting on personal health, as well as practicing stress management strategies such as mindful breathing and movement.

OBJECTIVE

The aims of this study are to (1) test the daily use of a wearable device to objectively measure physical and emotional well-being along with subjective assessments during pregnancy, and (2) explore the user's engagement with the Two Happy Hearts intervention prototype, as well as understand their experiences with various intervention components.

METHODS

A case study with a mixed design was used. We recruited a 29-year-old woman at 33 weeks of gestation with a singleton pregnancy. She had no medical complications or physical restrictions, and she was enrolled in the Medi-Cal public health insurance plan. The participant engaged in the Two Happy Hearts intervention prototype from her third trimester until delivery. The Oura smart ring was used to continuously monitor objective physical and emotional states, such as resting heart rate, resting heart rate variability, sleep, and physical activity. In addition, the participant self-reported her physical and emotional health using the Two Happy Hearts mobile app-based 24-hour recall surveys (sleep quality and level of physical activity) and ecological momentary assessment (positive and negative emotions), as well as the Perceived Stress Scale, Center for Epidemiologic Studies Depression Scale, and State-Trait Anxiety Inventory. Engagement with the Two Happy Hearts intervention was recorded via both the smart ring and phone app, and user experiences were collected via Research Electronic Data Capture satisfaction surveys. Objective data from the Oura ring and subjective data on physical and emotional health were described. Regression plots and Pearson correlations between the objective and subjective data were presented, and content analysis was performed for the qualitative data.

RESULTS

Decreased resting heart rate was significantly correlated with increased heart rate variability (r=-0.92, P<.001). We found significant associations between self-reported responses and Oura ring measures: (1) positive emotions and heart rate variability (r=0.54, P<.001), (2) sleep quality and sleep score (r=0.52, P<.001), and (3) physical activity and step count (r=0.77, P<.001). In addition, deep sleep appeared to increase as light and rapid eye movement sleep decreased. The psychological measures of stress, depression, and anxiety appeared to decrease from baseline to post intervention. Furthermore, the participant had a high completion rate of the components of the Two Happy Hearts intervention prototype and shared several positive experiences, such as an increased self-efficacy and a normal delivery.

CONCLUSIONS

The Two Happy Hearts intervention prototype shows promise for potential use by underserved pregnant women.

Acute fetal response to high-intensity interval training in the second and third trimesters of pregnancy

The majority of women do not meet the recommended levels of exercise during their pregnancies, frequently due to a lack of time. High-intensity interval training offers a potential solution, providing an effective, time-efficient exercise modality. This exercise modality has not been studied in pregnancy therefore, the objective of this study was to evaluate fetal response to a high-intensity interval training resistance circuit in the late second and early third trimesters of pregnancy. Fourteen active, healthy women with uncomplicated, singleton pregnancies participated in a high-intensity interval training resistance circuit between 28 + 0/7 and 32 + 0/7 weeks. A Borg rating of perceived exertion of 15-17/20 and an estimated heart rate of 80%-90% of maternal heart-rate maximum was targeted. Fetal well-being was evaluated continuously with fetal heart-rate tracings and umbilical artery Doppler velocimetry conducted pre-and post-exercise. Fetal heart rate tracings were normal throughout the exercise circuit. Post-exercise, umbilical artery end-diastolic flow was normal and significant decreases were observed in the mean systolic/diastolic ratios, pulsatility indexes and resistance indexes. Therefore, in a small cohort of active pregnant women, a high-intensity interval training resistance circuit in the late second and early third trimesters of pregnancy appears to be a safe exercise modality with no acute, adverse fetal effects but further study is required. Novelty: High-intensity interval training, at an intensity in excess of current recommendations, does not appear to be associated with any adverse fetal effects in previously active pregnant women. High-intensity interval training is an enjoyable and effective exercise modality in previously active pregnant women.

Exercise during Pregnancy: Developmental Programming Effects and Future Directions in Humans

Epidemiological studies show that low birth weight is associated with mortality from cardiovascular disease in adulthood, indicating that chronic diseases could be influenced by hormonal or metabolic insults encountered in utero. This concept, now known as the Developmental Origins of Health and Disease hypothesis, postulates that the intrauterine environment may alter the structure and function of the organs of the fetus as well as the expression of genes that impart an increased vulnerability to chronic diseases later in life. Lifestyle interventions initiated during the prenatal period are crucial as there is the potential to attenuate progression towards chronic diseases. However, how lifestyle interventions such as physical activity directly affect human offspring metabolism and the potential mechanisms involved in regulating metabolic balance at the cellular level are not known. The purpose of this review is to highlight the effects of exercise during pregnancy on offspring metabolic health and emphasize gaps in the current human literature and suggestions for future research.

Prenatal Exercise and Cardiovascular Health (PEACH) Study: Impact on the Vascular System

PURPOSE

Healthy pregnancy is typically associated with favorable vascular adaptations to both structure and function of the peripheral arteries. Exercise is independently associated with improvements in peripheral vascular health; however, the impact of exercise on prenatal adaptations is unclear. Therefore, we hypothesized that a structured aerobic exercise intervention between the second and third trimester (TM2 and TM3, respectively) of pregnancy would augment the already-positive changes in vascular outcomes.

METHODS

We recruited 59 inactive pregnant women (<20 weeks gestation) and randomized them into control (standard care; n = 28) or exercise (moderate intensity aerobic exercise, 3-4 days/week, 25-40 minutes, 14 ± 1 weeks; n = 31) conditions. Before and after the intervention all women completed comprehensive peripheral vascular assessment, which included blood markers of vascular health, carotid distensibility metrics, measures of arterial stiffness (pulse wave velocity; PWV), and [superficial] femoral artery reactivity during cold pressor test (CPT).

RESULTS

Carotid artery diameter increased from 6.5 mm to 6.9 mm (p < 0.001) strain (%)decreased from 9.9% to 8.4% (p < 0.001). Carotid artery blood flow, compliance and distensibility coefficients, stiffness (β), distensibility (1/β), and Elastic modulus were not different across gestation. PWV was not different across gestation. Superficial femoral artery diameter was increased from 5.4 mm to 5.6 mm (p = 0.004) while blood flow, conductance, and resistance at rest and during CPT were not different across gestation. None of our measures of vascular health were impacted by exercise.

CONCLUSION

We did not observe an impact of aerobic exercise on altering the changes across pregnancy in blood vessel health. However, the present study was conducted in women who were overall at low risk for developing gestational hypertension and should be interpreted with caution. Future work in high-risk women is needed.

Postprandial interval walking-effect on blood glucose in pregnant women with gestational diabetes

BACKGROUND

During pregnancy, postprandial hyperglycemia may increase the risk of complications such as fetal macrosomia. However, evidence on beneficial effects of physical activity on postprandial hyperglycemia is sparse.

OBJECTIVE

This study aimed to investigate the effect of 20 minutes of postprandial interval walking on glycemic control and glycemic variability in pregnant women diagnosed as having gestational diabetes mellitus.

STUDY DESIGN

A crossover controlled trial including 14 pregnant women (gestational age 31.8±1.3 weeks) diagnosed as having gestational diabetes mellitus (75 g oral glucose load with 2-hour venous plasma glucose of ≥9.0 mmol/L) was conducted. Participants completed a 4-day intervention period and a 4-day control period with 3 days in between. In each study period, participants received a fixed and identical diet. In the intervention period, participants engaged in 20 minutes of postprandial interval walking after breakfast, lunch, and dinner. Interval walking comprised alternating 3 minutes of slow and fast intervals. Interstitial glucose concentrations were determined during both study periods with a continuous glucose monitor. The mixed effects model was used to compare differences between exercise and no exercise.

RESULTS

Of note, 20 minutes of postprandial interval walking significantly reduced glycemic control during daytime hours relative to the control period (4-day mean glucose, 5.31 [5.04-5.59] vs 5.53 [5.25-5.81] mmol/L [95.6 (90.7-100.6) vs 99.5 (94.5-104.6) mg/dL]; P<.05). On each individual trial day, interval walking significantly reduced glycemic control during daytime hours on day 1 (mean glucose, 5.19 [4.92-5.47] vs 5.55 [5.27-5.83] mmol/L [93.4 (88.6-98.5) vs 99.9 (94.9-104.9) mg/dL]; P=.00), day 2 (mean glucose, 5.32 [5.05-5.60] vs 5.57 [5.29-5.84] mmol/L [95.8 (90.9-100.8) vs 100.3 (95.2-105.1) mg/dL]; P=.00), and day 3 (mean glucose, 5.27 [5.00-5.54] vs 5.46 [5.19-5.74] mmol/L [94.9 (90.0-99.7) vs 98.3 (93.4-103.3) mg/dL]; P=.00), but not on day 4.

CONCLUSION

A total of 20 minutes of postprandial interval walking seems to be an effective way to control postprandial glucose excursions in women with gestational diabetes mellitus.

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.

The Effectiveness of Smoking Cessation, Alcohol Reduction, Diet and Physical Activity Interventions in Improving Maternal and Infant Health Outcomes: A Systematic Review of Meta-Analyses

Diet, physical activity, smoking and alcohol behaviour-change interventions delivered in pregnancy aim to prevent adverse pregnancy outcomes. This review reports a synthesis of evidence from meta-analyses on the effectiveness of interventions at reducing risk of adverse health outcomes. Sixty-five systematic reviews (63 diet and physical activity; 2 smoking) reporting 602 meta-analyses, published since 2011, were identified; no data were identified for alcohol interventions. A wide range of outcomes were reported, including gestational weight gain, hypertensive disorders, gestational diabetes (GDM) and fetal growth. There was consistent evidence from diet and physical activity interventions for a significantly reduced mean gestational weight gain (ranging from -0.21 kg (95% confidence interval -0.34, -0.08) to -5.77 kg (95% CI -9.34, -2.21). There was evidence from larger diet and physical activity meta-analyses for a significant reduction in postnatal weight retention, caesarean delivery, preeclampsia, hypertension, GDM and preterm delivery, and for smoking interventions to significantly increase birth weight. There was no statistically significant evidence of interventions having an effect on low or high birthweight, neonatal intensive care unit admission, Apgar score or mortality outcomes. Priority areas for future research to capitalise on pregnancy as an opportunity to improve the lifelong wellbeing of women and their children are highlighted.

To HIIT or not to HIIT? The question pregnant women may be searching for online: a descriptive observational study

AIMS

An increasingly popular exercise modality for women is high-intensity interval training (HIIT). Limited research has assessed HIIT during pregnancy, and as a result, pregnant women may inquire about HIIT on their own through online searches. The purpose of this study was to systematically search and critically evaluate online resources that women may access when inquiring about performing HIIT during pregnancy.

METHODS

Following previously published methodology, we systematically examined the online search engine Google with the terms 'HIIT' and 'pregnancy'. Using the 2019 Canadian Guideline for Physical Activity throughout Pregnancy as a reference, we identified evidence-based safety recommendations that apply to all prenatal exercise regimes. All selected links were assessed for whether or not they included evidence-based exercise and pregnancy safety recommendations. Descriptive analyses were performed to report the frequency of each construct.

RESULTS

Seventy-six links were retrieved, and 33 relevant links were selected for inclusion. The majority of the retrieved links recommended that women should consult a healthcare provider before beginning any exercise programme (67%), and modify the intensity and types of exercises in the active HIIT bout based on general pregnancy-related changes (73%) and individual comfort level (55%). Just under half of the links recommended modifying intensity based on prepregnancy activity level (46%), offered trimester-specific recommendations (42%), and only 12% mentioned contraindications to exercise.

CONCLUSION

Publicly accessible information online on HIIT during pregnancy does not routinely adhere to evidence-based safety recommendations for prenatal exercise. Further research on HIIT during pregnancy and public dissemination of findings is required.

Markers of branched-chain amino acid catabolism are not affected by exercise training in pregnant women with obesity

Despite the role of branched-chain amino acids (BCAAs) in physiological processes such as nutrient signaling and protein synthesis, there is ongoing debate about the link between circulating BCAAs and insulin resistance (IR) in various populations. In healthy women, IR mildly increases during pregnancy, whereas both BCAAs and markers of BCAA catabolism decrease, indicating that fetal growth is being prioritized. Exercise reduces IR in nonpregnant adults, but less is known about the effect of exercise during pregnancy in women with obesity on IR and BCAA breakdown. The aim of this study was to determine the effect of a moderate-intensity exercise intervention during pregnancy on maternal circulating BCAAs and markers of BCAA catabolism [short-chain acylcarnitines (ACs)], and their associations with IR. Healthy obese [n = 80, means ± SD; body mass index (BMI): 36.9 ± 5.7 kg/m²] pregnant women were randomized into an exercise (n = 40, aerobic/resistance 3×/wk, ∼13th gestation week until birth) or a nonexercise control (n = 40) group. Blood was collected at 12.2 ± 0.5 and 36.0 ± 0.4 gestation weeks and analyzed for BCAA-derived acylcarnitine concentrations as markers of BCAA breakdown toward oxidative pathways, and glucose and insulin concentrations [updated homeostatic model assessment of IR (HOMA2-IR)]. After adjusting for HOMA2-IR, there were no interaction effects of group by time. In addition, there was a main positive effect of time on HOMA2-IR (12 wk: 2.3 ± 0.2, 36 wk: 3.0 ± 0.2, P = 0.003). A moderate-intensity exercise intervention during pregnancy in women with obesity was not associated with changes in BCAA-derived ACs versus standard of care. The decrease in BCAA-derived ACs throughout gestation could not be explained by IR.NEW & NOTEWORTHY This research showed an increase in insulin resistance (IR) and decrease in branched-chain amino acid catabolism throughout gestation in women with obesity, and addition of a moderate exercise intervention (known to attenuate IR in nonpregnant populations) did not alter these shifts. Findings provide support for metabolic safety of exercise during pregnancy.

Is yoga considered exercise within systematic reviews of exercise interventions? A scoping review

OBJECTIVE

Yoga is an increasingly popular choice of exercise for the Western population, with people engaging in yoga for a range of physical and mental health and well-being reasons. The aim of this scoping review is to examine whether yoga is considered an exercise modality within relevant leading journals, as evidenced by its consideration in systematic reviews (SRs) of exercise interventions for health-related outcomes.

METHODS

Design: Scoping review.

DATA SOURCES

Three leading sources (Sports Medicine, British Journal of Sports Medicine and Cochrane Collaboration) were searched. Eligibility criteria for selecting studies: The ten most recently published systematic reviews of exercise interventions for health-related outcomes from each journal were included (N = 30) that met these criteria: systematic review studying humans participating in general exercise and measuring a health-related outcome. Exercise interventions with any specific qualifying terms (e.g. aquatic, strength, aerobic) were excluded.

RESULTS

The articles retrieved were published between 2007 and 2019, and collectively included 991 interventions. Seven reviews explicitly stated that yoga was to be included/excluded while twenty-three studies made no mention of how yoga was being considered in the methodology. Five studies included yoga in the search strategy, implying its inclusion. Post-hoc analyses found that the definitions of exercise in general were also variable. Exercise definition specificity was not associated with whether or not yoga was assessed for inclusion.

CONCLUSIONS

Systematic reviews of exercise and physical activity interventions for health-related outcomes do not consistently make clear whether or not they include or exclude yoga as a form of exercise.

Prenatal Exercise and Cardiorespiratory Health and Fitness: A Meta-analysis

PURPOSE

This study aimed to examine the influence of prenatal exercise on maternal cardiorespiratory health and fitness during pregnancy.

METHODS

Online databases were searched up to February 25, 2019. Studies of randomized controlled trials (RCTs) were eligible, which contained information on the relevant population (pregnant women), intervention (subjective or objective measures of frequency, intensity, duration, volume, or type of exercise), comparator (no exercise intervention), and outcomes (maternal cardiorespiratory fitness, including V˙O2max, submaximal V˙O2, V˙O2 at anaerobic threshold, and cardiorespiratory health, including resting heart rate, and resting systolic and diastolic blood pressures during pregnancy).

RESULTS

From 2699 unique citations, 26 RCTs (N = 2292 women) were included. Of these, one study reported measured V˙O2max, seven reported predicted V˙O2max, three reported submaximal V˙O2, and two studies reported VO2AT. "Low"- to "high"-certainty evidence revealed that exercise was associated with improved predicted/measured V˙O2max (5 RCTs, n = 430; mean difference [MD], 2.77 mL·kg·min; 95% confidence interval [CI], 0.32 to 5.21 mL·kg·min; I = 69%), reduced resting heart rate (9 RCTs, n = 637; MD, -1.71 bpm; 95% CI, -3.24 to -0.19 bpm; I = 13%), resting systolic blood pressure (16 RCTs, n = 1672; MD, -2.11 mm Hg; 95% CI, -3.71 to -0.51 mm Hg; I = 69%), and diastolic blood pressure (15 RCTs, n = 1624; MD, -1.77 mm Hg; 95% CI, -2.90 to -0.64 mm Hg; I = 60%).

CONCLUSION

Prenatal exercise interventions improve maternal predicted/measured V˙O2max and reduce resting heart rate and blood pressure. This review highlights the need for additional high-quality studies of cardiorespiratory fitness (namely, V˙O2max and V˙O2 peak) in pregnancy.PROSPERO registration number: CRD42019131249.

Cardiopulmonary exercise testing during pregnancy

The goal of this review is to examine practical considerations when conducting cardiopulmonary exercise testing during pregnancy. In a clinical and research setting, cardiopulmonary exercise testing during pregnancy is valuable in identifying underlying cardiopulmonary conditions, stratifying the risk of adverse pregnancy outcomes, as well as establishing exercise tolerance/limitations. This review encompasses information regarding the unique physiological adaptations that occur throughout gestation (e.g., changes in resting heart rate, blood pressure, glucose, etc.) and how these adaptations impact the interpretation of physiological measurements. There are also key concerns that are unique to pregnant populations that should be considered when participating in exercise (i.e., fetus, ventilation, thermoregulation, urinary incontinence, low back pain, and pelvic girdle pain). This step-by-step review of cardiopulmonary exercise testing outlines pregnancy related adjustments to standardized methods (i.e., screening/documentation, pre- and post-test measurements, protocol specifics, modality selection, and fetal monitoring) which should be considered for the safety of both the participant and fetus. Currently, pregnancy specific exercise testing guidelines are lacking. Therefore, we will be discussing the limitations of current recommendations such as a safe cut off for resting heart rate and pregnancy specific test termination criteria.

Adaptation of an exercise intervention for pregnant women to community-based delivery: a study protocol

INTRODUCTION

Despite well-established guidelines and benefits to exercise, the majority of pregnant women in the USA fail to meet recommended activity levels. Studies need to determine feasible ways to translate clinical interventions to community settings by engaging pregnant women in widely accessible locations to ensure benefits to more women. The aim of this study is to adapt and determine feasibility, acceptability and fidelity of the research clinic-based Expecting intervention (NCT02125149) with pregnant women with obesity in community settings.

METHODS AND ANALYSIS

We will use the Replicating Effective Programs (REP) to guide the adaptation and implementation of the research clinic-based intervention into the community. REP provides a four-phase process for implementing evidence-based interventions including collection of feedback from community stakeholders, iterative piloting of the intervention in the community and a process for standardising the intervention across community settings. Following adaptation, the updated intervention will be piloted. The pilot study will include 60 expecting women. We will randomise half to receive the community-adapted Expecting intervention (intervention, N=30) and half to receive standard of care (control, N=30). Feasibility and Acceptability of Intervention Measures are primary outcomes as key indicators of feasibility. Secondary outcomes will include the number of intervention sessions completed, the change in the number of minutes of physical activity as measured by accelerometer, as well as change in health indicators from enrolment to time of delivery and 6 months post-delivery (ie, body mass index, blood pressure and total cholesterol).

ETHICS AND DISSEMINATION

This study has been approved by the Institutional Review Board (#260132). Findings will be shared with study participants and stakeholder advisors through written summaries and in-person presentations; results will also be shared through presentations at scientific conferences and publications in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04298125; Pre-results.

Why can't I exercise during pregnancy? Time to revisit medical 'absolute' and 'relative' contraindications: systematic review of evidence of harm and a call to action

BACKGROUND

Clinical guidelines recommend pregnant women without contraindication engage in regular physical activity. This is based on extensive evidence demonstrating the safety and benefits of prenatal exercise. However, certain medical conditions or contraindications warrant a reduction, modification or cessation of activity due to potential health risks.

AIM

To review and evaluate the evidence related to medical disorders which may warrant contraindication to prenatal exercise.

METHODS

Online databases were searched up to 5 April 2019. Forty-four unique studies that reported data on our Population (pregnant women with contraindication to exercise), Intervention (subjective/objective measures of acute or chronic exercise), Comparator (not essential) and Outcomes (adverse maternal or fetal outcomes) were included in the review.

KEY FINDINGS

We found that the majority of medical conditions listed as contraindications were based on expert opinion; there is minimal empirical evidence to demonstrate harm of exercise and benefit of activity restriction. We identified 11 complications (eg, gestational hypertension, twin pregnancy) previously classified as contraindications where women may in fact benefit from regular prenatal physical activity with or without modifications. However, the evidence suggests that severe cardiorespiratory disease, placental abruption, vasa previa, uncontrolled type 1 diabetes, intrauterine growth restriction, active preterm labour, severe pre-eclampsia and cervical insufficiency are associated with strong potential for maternal/fetal harm and warrant classification as absolute contraindications.

CONCLUSION

Based on empirical evidence, we provide a call to re-evaluate clinical guidelines related to medical disorders that have previously been considered contraindications to prenatal exercise. Removing barriers to physical activity during pregnancy for women with certain medical conditions may in fact be beneficial for maternal-fetal health outcomes.

Cycling reduces blood glucose excursions after an oral glucose tolerance test in pregnant women: a randomized crossover trial

The aim of this study was to evaluate the effect of an acute bout of cycling immediately after oral glucose intake on glucose metabolism in pregnant women at risk for gestational diabetes mellitus (GDM). Fifteen pregnant women with BMI ≥ 27 kg/m² were enrolled in a randomized crossover controlled study and underwent two oral glucose tolerance tests (OGTTs) ingesting 75 g of glucose followed by either 20 min of stationary cycling at moderate intensity (65%-75% maximal heart rate) or rest. Using continuous glucose monitors, glucose was measured up to 48 h after the OGTT. Glucose, insulin, and C-peptide were determined at baseline and after 1 and 2 h. One hour after glucose intake, mean blood glucose was significantly lower after cycling compared with rest (p = 0.002). Similarly, mean glucose peak level was significantly lower after cycling compared with after rest (p = 0.039). Lower levels of insulin and C-peptide were observed after 1 h (p < 0.01). Differences in glucose measurements after 2 h and up to 48 h were not statistically different. We found that 20 min of cycling at moderate intensity after glucose intake reduced blood glucose excursions in pregnant women at risk for GDM. ClinicalTrials.gov Identifier: NCT03644238. Novelty Bullets In pregnant women, we found that cycling after glucose intake resulted in significantly lower glucose levels compared with rest. The exercise intervention studied is feasible for pregnant women and could be readily used to reduce glucose excursions.

Spotlight on the fetus: how physical activity during pregnancy influences fetal health: a narrative review

Before and during pregnancy, women often aim to improve their lifestyle so as to provide a healthier environment for their developing child. It remains unresolved, however, as to whether physical activity (PA) during pregnancy poses a possible risk or whether it might even have beneficial effects on the developing child. There is increasing evidence that PA during pregnancy is indeed beneficial to maternal physiological and psychological health and that it is generally not detrimental to the fetal cardiovascular system and neuronal function in the developing child. This also led to international recommendations for PAs during pregnancy. In the current review, we aimed to comprehensively assess the evidence of beneficial and harmful effects of maternal PA, including high-performance sports, on fetal development. The different mental and body-based relaxation techniques presented here are frequently performed during pregnancy. We found a considerable number of studies addressing these issues. In general, neither low key, moderate maternal PA nor relaxation techniques were observed to have a harmful effect on the developing child. However, we identified some forms of PA which could have at least a transient unfavourable effect. Notably, the literature currently available does not provide enough evidence to enable us to make a general conclusive statement on this subject. This is due to the lack of longitudinal studies on the metabolic and cognitive effects of regular PA during pregnancy and the wide diversity of methods used. In particular, the kind of PA investigated in each study differed from study to study.

Review of Recent Physical Activity Guidelines During Pregnancy to Facilitate Advice by Health Care Providers

Importance

Physical activity during pregnancy can offer many maternal and fetal health benefits.

Objective

The aim was to summarize American, Canadian, and international recommendations published recently on physical activity during pregnancy to aid health care providers in their delivery of advice on the topic.

Evidence Acquisition

A descriptive review of 3 national guidelines and 1 international guideline on physical activity during pregnancy was conducted. The guidelines included the 2019 Canadian recommendations, the 2018 United States' Physical Activity Guidelines for Americans (second edition), the 2015 (reaffirmed in 2017) American College of Obstetrics and Gynecology guideline, and the 2016-2018 International Olympic Committee recommendations for recreational and elite athletes.

Results

For apparently healthy women, under the guidance of their health care provider, moderate-intensity physical activity using both aerobic and muscle conditioning activities is recommended. The guidelines recommended at least 150 min/wk spread throughout the week (Canada, United States) or at least 20 to 30 min/d (American College of Obstetrics and Gynecology).

Conclusions and Relevance

This summary of 4 recent guidelines can facilitate use of updated recommendations by health care providers regarding physical activity during pregnancy. More detailed evidence-based guidelines on physical activity during postpartum are needed.

Exercise in Pregnant Women with Diabetes

PURPOSE OF REVIEW

Diabetes affects an increasing number of pregnancies. Regular exercise is recommended for pregnant women without diabetes, but whether exercise during pregnancy also benefits women with gestational diabetes (GDM) or preexisting (type 1 or type 2) diabetes or if these women have any specific risks is unclear.

RECENT FINDINGS

Recent evidence suggests that low- to moderate-intensity exercise improves blood glucose and may delay insulin initiation for women with GDM. Exercise is also safe, with no reports of increased maternal or neonatal complications. Few studies evaluated exercise as adjunct therapy for pregnant women with preexisting diabetes, precluding a thorough assessment in this population. Low- to moderate-intensity exercise during pregnancy safely improves glycemic control among women with GDM. More studies are needed to evaluate the impact of exercise in pregnant women with preexisting diabetes. Whether a specific type, volume, or timing of activity is most effective is not known.

Energy Intake Requirements in Pregnancy

Energy intake requirements in pregnancy match the demands of resting metabolism, physical activity, and tissue growth. Energy balance in pregnancy is, therefore, defined as energy intake equal to energy expenditure plus energy storage. A detailed understanding of these components and their changes throughout gestation can inform energy intake recommendations for minimizing the risk of poor pregnancy outcomes. Energy expenditure is the sum of resting and physical activity-related expenditure. Resting metabolic rate increases during pregnancy as a result of increased body mass, pregnancy-associated physiological changes, i.e., cardiac output, and the growing fetus. Physical activity is extremely variable between women and may change over the course of pregnancy. The requirement for energy storage depends on maternal pregravid body size. For optimal pregnancy outcomes, women with low body weight require more fat mass accumulation than women with obesity, who do not require to accumulate fat mass at all. Given the high energy density of fat mass, these differences affect energy intake requirements for a healthy pregnancy greatly. In contrast, the energy stored in fetal and placental tissues is comparable between all women and have small impact on energy requirements. Different prediction equations have been developed to quantify energy intake requirements and we provide a brief review of the strengths and weaknesses and discuss their application for healthy management of weight gain in pregnant women.

Current Resources for Evidence-Based Practice, March 2019

A review of new resources to support the provision of evidence-based care for women and infants.

Determinants of Maternal Insulin Resistance during Pregnancy: An Updated Overview

Insulin resistance changes over time during pregnancy, and in the last half of the pregnancy, insulin resistance increases considerably and can become severe, especially in women with gestational diabetes and type 2 diabetes. Numerous factors such as placental hormones, obesity, inactivity, an unhealthy diet, and genetic and epigenetic contributions influence insulin resistance in pregnancy, but the causal mechanisms are complex and still not completely elucidated. In this review, we strive to give an overview of the many components that have been ascribed to contribute to the insulin resistance in pregnancy. Knowledge about the causes and consequences of insulin resistance is of extreme importance in order to establish the best possible treatment during pregnancy as severe insulin resistance can result in metabolic dysfunction in both mother and offspring on a short as well as long-term basis.

2019 Canadian guideline for physical activity throughout pregnancy

The objective is to provide guidance for pregnant women and obstetric care and exercise professionals on prenatal physical activity. The outcomes evaluated were maternal, fetal or neonatal morbidity, or fetal mortality during and following pregnancy. Literature was retrieved through searches of MEDLINE, EMBASE, PsycINFO, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Scopus and Web of Science Core Collection, CINAHL Plus with Full Text, Child Development & Adolescent Studies, Education Resources Information Center, SPORTDiscus, ClinicalTrials.gov and the Trip Database from inception up to 6 January 2017. Primary studies of any design were eligible, except case studies. Results were limited to English-language, Spanish-language or French-language materials. Articles related to maternal physical activity during pregnancy reporting on maternal, fetal or neonatal morbidity, or fetal mortality were eligible for inclusion. The quality of evidence was rated using the Grading of Recommendations Assessment, Development and Evaluation methodology. The Guidelines Consensus Panel solicited feedback from end users (obstetric care providers, exercise professionals, researchers, policy organisations, and pregnant and postpartum women). The development of these guidelines followed the Appraisal of Guidelines for Research and Evaluation II instrument. The benefits of prenatal physical activity are moderate and no harms were identified; therefore, the difference between desirable and undesirable consequences (net benefit) is expected to be moderate. The majority of stakeholders and end users indicated that following these recommendations would be feasible, acceptable and equitable. Following these recommendations is likely to require minimal resources from both individual and health systems perspectives.

Impact of prenatal exercise on neonatal and childhood outcomes: a systematic review and meta-analysis

Objective

We aimed to identify the relationship between maternal prenatal exercise and birth complications, and neonatal and childhood morphometric, metabolic and developmental outcomes.

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 published in English, Spanish or French, and contained information on the relevant population (pregnant women without contraindication to exercise), intervention (subjective/objective measures of frequency, intensity, duration, volume or type of exercise, alone (‘exercise-only’) or in combination with other intervention components (eg, dietary; ‘exercise+cointervention’)), comparator (no exercise or different frequency, intensity, duration, volume, type or trimester of exercise) and outcomes (preterm birth, gestational age at delivery, birth weight, low birth weight (<2500 g), high birth weight (>4000 g), small for gestational age, large for gestational age, intrauterine growth restriction, neonatal hypoglycaemia, metabolic acidosis (cord blood pH, base excess), hyperbilirubinaemia, Apgar scores, neonatal intensive care unit admittance, shoulder dystocia, brachial plexus injury, neonatal body composition (per cent body fat, body weight, body mass index (BMI), ponderal index), childhood obesity (per cent body fat, body weight, BMI) and developmental milestones (including cognitive, psychosocial, motor skills)).

Results

A total of 135 studies (n=166 094) were included. There was ‘high’ quality evidence from exercise-only randomised controlled trials (RCTs) showing a 39% reduction in the odds of having a baby >4000 g (macrosomia: 15 RCTs, n=3670; OR 0.61, 95% CI 0.41 to 0.92) in women who exercised compared with women who did not exercise, without affecting the odds of growth-restricted, preterm or low birth weight babies. Prenatal exercise was not associated with the other neonatal or infant outcomes that were examined.

Conclusions

Prenatal exercise is safe and beneficial for the fetus. Maternal exercise was associated with reduced odds of macrosomia (abnormally large babies) and was not associated with neonatal complications or adverse childhood outcomes.