Is supine exercise associated with adverse maternal and fetal outcomes? A systematic review

Midwives' Knowledge, Attitudes, and Professional Practices Regarding Prenatal Physical Activity

Background/Objectives: Prenatal physical activity (PA) offers numerous health benefits for both the mother and her child, yet few pregnant women are sufficiently active enough to obtain these benefits. Midwives play an important role in promoting prenatal PA. However, little is known about the content of the information they share with their clients regarding prenatal PA, how they communicate it, and the personal factors that might influence their counseling. In the context of prenatal PA guidance, the aim of this study was to describe the knowledge, attitudes, professional practices, and communication methods used by midwives. Methods: A cross-sectional descriptive study was conducted between February and June 2024 among midwives working in the Province of Quebec. An electronic questionnaire including both closed (quantitative data) and open-ended (qualitative data) questions was developed. Results: Fifty midwives were included in the analysis. Only 28 (56%) reported being aware of the latest Canadian guidelines for PA throughout pregnancy. The recommendations provided varied in terms of content and accuracy but were often conservative (i.e., not focused on increasing PA). Forty-five (90%) mentioned providing information on PA to their pregnant client, and eighty-four (84%) said they used bidirectional communication to share this information. The vast majority (84%) did not consider their counseling to be optimal, primarily due to a lack of training and knowledge. Conclusions: Our finding allowed us to gain a better understanding of current midwifery knowledge, attitudes, and professional practices regarding prenatal PA and to initiate a reflection on how to improve their knowledge, skills, and confidence in guiding their client toward prenatal PA.

Maternal and fetal responses to acute high-intensity resistance exercise during pregnancy

OBJECTIVE

To examine maternal and fetal cardiovascular responses to high-intensity resistance exercise in pregnancy.

METHODS

10 healthy pregnant (26.4±3.2 weeks gestation) and 10 healthy non-pregnant individuals were recruited (34.8±6 and 33.5±2.9 years, respectively). At least 48 hours after baseline strength testing to determine 10-repetition maximum (10 RM), participants completed 10 repetitions of barbell back squat, bench press and deadlift at 70%, 80% and 90% of 10 RM with free breathing, followed by 10 repetitions at 90% 10 RM with a Valsalva manoeuvre. Maternal heart rate was monitored continuously. Fetal heart rate, umbilical systolic/diastolic (S/D) ratio, resistive index (RI) and pulsatility index (PI), as well as maternal blood pressure, glucose and lactate were assessed immediately before and after exercise.

RESULTS

The amount of weight lifted and the rate of perceived exertion by pregnant and non-pregnant participants were similar throughout each exercise. Maternal heart rate increased with the amount of weight lifted, peaking with the use of the Valsalva manoeuvre (squat: 137.3±8.4 bpm; bench press: 110.5±10.4 bpm; deadlift: 130.7±9.0 bpm). Fetal bradycardia was not observed, and fetal heart rate did not change from pre-to-post exercise (squat: p=0.639; bench press: p=0.682; deadlift: p=0.847). Umbilical blood flow metrics, such as RI, remained within normal ranges throughout each set of squats (p=0.642), bench press (p=0.287) and deadlifts (p=0.614).

CONCLUSION

Our findings suggest that high-intensity resistance exercises are well tolerated by both mother and fetus, including while using the Valsalva manoeuvre.

Maternal physical activity in healthy pregnancy: Effect on fetal oxygen supply

AIM

We review evidence for effects of physical activity before and during gestation on the course of pregnancy and ask if there are circumstances where physical activity can stress the fetus due to competition for oxygen and energy substrates.

RESULTS

We first summarize physiological responses to exercise in nonpregnant people and known physiological adaptations to pregnancy. Comparing the two, we conclude that physical activity prior to and continuing during gestation is beneficial to pregnancy outcome. The effect of starting an exercise regimen during pregnancy is less easy to assess as few studies have been undertaken. Results from animal models suggest that the effects of maternal exercise on the fetus are transient; the fetus can readily compensate for a short-term reduction in oxygen supply.

CONCLUSION

In general, we conclude that physical activity before and during pregnancy is beneficial, and exercise started during pregnancy is unlikely to affect fetal development. We caution, however, that there are circumstances where this may not apply. They include the intensive exercise regimens of elite athletes and pregnancies at high altitudes where hypoxia occurs even in the resting state.

Balancing benefits and risks of exercise in pregnancy: a qualitative analysis of social media discussion

Exercise improves pregnancy outcomes, but few pregnant individuals meet physical activity guidelines. The main objective of this study was to explore the perception of exercise during pregnancy using posts and comments on Reddit, a large social media platform. Relevant user-generated posts and comments were identified on Reddit by searching systematically for a combination of keywords related to pregnancy and exercise. A dataset of 120 posts and 2892 comments was randomly selected for reflexive thematic analysis. Three themes relating to perceptions of benefits and risks to exercise in pregnancy and how they influence decision-making were generated: (1) perceived benefits of exercise: 'We all know that exercise is good for us'; (2) perceived risks of exercise: Exercise as 'off limits'; and (3) information seeking and decision-making: 'I'm kinda stumped on exercise'. While the benefits of exercise during pregnancy are well recognised among Reddit users, perceived risks significantly influence their decisions to start, continue, adjust or stop exercising. Healthcare providers play a crucial role in guiding these exercise choices, emphasising the need for them to provide evidence-based advice and support pregnant individuals in achieving optimal physical activity levels. Addressing misinformation and providing supportive counselling can help pregnant individuals navigate the complexities of exercise during this critical period.

Does Pelvic Floor Muscle Exercise Change the Hemodynamic Responses of the Inferior Vena Cava in Pregnant Women? A Prospective-Controlled Study

INTRODUCTION AND HYPOTHESIS

This study was aimed at exploring the immediate impacts of pelvic floor muscle exercises (PFMEs) on various maternal physiological parameters in pregnant women.

METHODS

The study included a total of 52 women, 26 pregnant (Pregnant group: 28.04±6.01 years; 26.83±3.81 kg/m2) and 26 nonpregnant (Control group: 29.42±5.73 years; 25.41±3.03 kg/m2) individuals. All women received PFME as follows: PFME was performed for 5 min (6-s holding contraction, 10 s of relaxation, 3 rapid PFM contractions). Evaluations were conducted before, immediately after, and 5 min post-exercise, with measurements including inferior vena cava (IVC) diameters and pulsatility index, blood pressure, oxygen saturation, and heart rates. Two-way analysis of variance was performed for group and time comparisons in repeated measurements.

RESULTS

In both groups, the IVC collapsibility index values were lower 5 min after exercise, although this decrease, although clinically significant, did not reach statistical significance (p = 0.057). Post-exercise systolic blood pressure significantly decreased in both groups, whereas diastolic blood pressure decreased significantly in the pregnant group (p = 0.001, p = 0.023).

CONCLUSIONS

The study found no statistically significant changes in the collapsibility index of the IVC after PFME but observed a clinically suggestive decrease. The clinical decrease in the collapsibility index can be interpreted as PFME in the supine position increasing venous return. Additionally, PFME was found not to alter maternal and fetal heart rates but contributed to the decrease in maternal systolic and diastolic blood pressure. Our study supports the view that the acute effects of PFME neither induce fetal stress nor pose maternal risks.

Impact of maternal posture on fetal physiology in human pregnancy: a narrative review

In numerous medical conditions, including pregnancy, gravity and posture interact to impact physiology and pathophysiology. Recent investigations, for example, pertaining to maternal sleeping posture during the third trimester and possible impact on fetal growth and stillbirth risk highlight the importance and potential clinical implications of the subject. In this review, we provide an extensive discussion of the impact of maternal posture on fetal physiology from conception to the postpartum period in human pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 242 studies from 1991 through 2021, inclusive, that met our inclusion criteria. Herein, we provide a synthesis of the resulting literature. In the first section of the review, we group the results by the impact of maternal posture at rest on the cervix, uterus, placenta, umbilical cord, amniotic fluid, and fetus. In the second section of the review, we address the impact on fetal-related outcomes of maternal posture during various maternal activities (e.g., sleep, work, exercise), medical procedures (e.g., fertility, imaging, surgery), and labor and birth. We present the published literature, highlight gaps and discrepancies, and suggest future research opportunities and clinical practice changes. In sum, we anticipate that this review will shed light on the impact of maternal posture on fetal physiology in a manner that lends utility to researchers and clinicians who are working to improve maternal, fetal, and child health.

Public health guidelines for physical activity during pregnancy from around the world: a scoping review

BACKGROUND AND OBJECTIVE

Despite the known health benefits of physical activity (PA), pregnancy is a time of marked decline in PA levels. To provide women with reliable and trustworthy information, and to encourage greater participation in PA during pregnancy, many governments have developed guidelines for PA during pregnancy. Our aim was to synthesise the most recent public health guidelines on PA during pregnancy from different countries in order to understand the nature and extent of advice that is available.

DESIGN

Scoping review.

DATA SOURCES

Search of the grey literature, direct contact with international experts, screening of relevant academic literature and citation searching.

ELIGIBILITY CRITERIA

Public health guidelines developed or endorsed by government departments published since 2010.

RESULTS

Our search located 30 eligible guidelines, published in 11 different languages. There is remarkable concordance in the advice offered. For women with uncomplicated pregnancy, guidelines recommend: 150-300 min/week of moderate intensity aerobic activity; pelvic floor and muscle strengthening exercises; modification of some exercises (eg, supine position); and provide lists of warning signs to cease activity (eg, persistent dizziness, vaginal bleeding) and activities that should be avoided (eg, if high risk of falling/collision). Few guidelines offer specific advice for highly active women (eg, athletes), or trimester-specific or culturally specific considerations.

CONCLUSIONS

This review provides a summary of public health recommendations for PA during pregnancy around the world. The challenge is now to ensure that all who provide healthcare for women understand the guidelines and encourage safe participation in PA during pregnancy.

Impact of heavy resistance training on pregnancy and postpartum health outcomes

INTRODUCTION AND HYPOTHESIS

Participation in Olympic weightlifting, the Valsalva maneuver, and acute or prolonged supine weightlifting during pregnancy are cautioned against; however, these recommendations are based on expert opinions as opposed to empirical evidence. The aim of this study was to examine the training and health outcomes of individuals who engaged in heavy resistance training during pregnancy.

METHODS

A total of 679 individuals who lifted at least 80% one-repetition maximum during pregnancy participated in an online survey.

RESULTS

Participants were primarily recreational athletes (88%, 332 out of 675) engaged in CrossFit™ (61%, 410 out of 675) and/or weightlifting (49%, 332 out of 675) during pregnancy. Most participants reported no complications during pregnancy or delivery (66%, 388 out of 589), whereas 57% (241 out of 426) reported urinary incontinence following pregnancy. Participants who maintained pre-pregnancy training levels until delivery reported significantly less reproductive complications than those who ceased training levels prior to delivery (p = 0.006). Most respondents engaged in Olympic lifting (72%, 311 out of 432) and lifting in a supine position (71%, 306 out of 437), whereas fewer reported use of the Valsalva maneuver during pregnancy (34%, 142 out of 412). Most returned to weightlifting following delivery (89%, 400 out of 447, average: 3.2 ± 3.0 months), including Olympic lifting (81%, 300 out of 372, average: 4.0 ± 3.4 months) and Valsalva (62%, 213 out of 341, average: 4.5 ± 3.6 months).

CONCLUSIONS

Individuals who engaged in heavy prenatal resistance training had typical perinatal and pelvic floor health outcomes that were not altered whether they engaged in, or avoided Olympic lifting, Valsalva or supine weightlifting.

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.

Maternal Obesity: A Focus on Maternal Interventions to Improve Health of Offspring

Maternal obesity has many implications for offspring health that persist throughout their lifespan that include obesity and cardiovascular complications. Several different factors contribute to obesity and they encompass interplay between genetics and environment. In the prenatal period, untreated obesity establishes a foundation for a myriad of symptoms and negative delivery experiences, including gestational hypertensive disorders, gestational diabetes, macrosomia, and labor complications. However, data across human and animal studies show promise that nutritional interventions and physical activity may rescue much of the adverse effects of obesity on offspring metabolic health. Further, these maternal interventions improve the health of the offspring by reducing weight gain, cardiovascular disorders, and improving glucose tolerance. Mechanisms from animal studies have also been proposed to elucidate the signaling pathways that regulate inflammation, lipid metabolism, and oxidative capacity of the tissue, ultimately providing potential specific courses of treatment. This review aims to pinpoint the risks of maternal obesity and provide plausible intervention strategies. We delve into recent research involving both animal and human studies with maternal interventions. With the increasing concerning of obesity rates witnessed in the United States, it is imperative to acknowledge the long-term effects posed on future generations and specifically modify maternal nutrition and care to mitigate these adverse outcomes.

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.

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.

Physical Activity and Exercise During Pregnancy and the Postpartum Period: ACOG Committee Opinion, Number 804

Exercise, defined as physical activity consisting of planned, structured, and repetitive bodily movements done to improve one or more components of physical fitness, is an essential element of a healthy lifestyle, and obstetrician-gynecologists and other obstetric care providers should encourage their patients to continue or to commence exercise as an important component of optimal health. Women who habitually engaged in vigorous-intensity aerobic activity or who were physically active before pregnancy can continue these activities during pregnancy and the postpartum period. Observational studies of women who exercise during pregnancy have shown benefits such as decreased gestational diabetes mellitus, cesarean birth and operative vaginal delivery, and postpartum recovery time. Physical activity also can be an essential factor in the prevention of depressive disorders of women in the postpartum period. Physical activity and exercise in pregnancy are associated with minimal risks and have been shown to benefit most women, although some modification to exercise routines may be necessary because of normal anatomic and physiologic changes and fetal requirements. In the absence of obstetric or medical complications or contraindications, physical activity in pregnancy is safe and desirable, and pregnant women should be encouraged to continue or to initiate safe physical activities. This document has been revised to incorporate recent evidence regarding the benefits and risks of physical activity and exercise during pregnancy and the postpartum period.

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.

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.