Longitudinal Changes in Physical Activity during Pregnancy: National Institute of Child Health and Human Development Fetal Growth Studies.

INTRODUCTION: Exercise in pregnancy is associated with many perinatal benefits, but patterns of home, work, and commuting activity are not well described. We investigated longitudinal activity in singleton and twin pregnancy by activity domain and maternal characteristics. METHODS: In the National Institute of Child Health and Human Development Fetal Growth Studies cohorts, 2778 women with singleton and 169 women with twin gestations reported activity using the Pregnancy Physical Activity Questionnaire at up to six or seven study visits, respectively. Metabolic equivalent of task-hours per week (MET-h·wk -1 ) was calculated from reported activity. Baseline measurements (obtained between 10 and 13 wk) reflected past year activity. Linear mixed models estimated MET-h·wk -1 by domain (household/childcare, occupational, inactive, transportation, sports/exercise), self-reported race/ethnicity (non-Hispanic White, non-Hispanic Black, Hispanic, Asian/Pacific Islander), prepregnancy body mass index (<25, 25 to < 30, ≥30 kg·m -2 ), parity (0, ≥1), baseline activity (quartiles), and plurality (singleton, twin). RESULTS: Household/caregiving activity made up the largest fraction of reported MET-h·wk -1 at baseline (42%), followed by occupational activity (28%). Median summed activity declined 47%, from 297 to 157 MET-h·wk -1 , between 10 and 40 wk, largely driven by changes in household/caregiving (44% decline), and occupational activity (63% decline). Sports/exercise activity declined 55% but constituted only 5% of reported MET-h·wk -1 at baseline. At baseline, non-Hispanic Black women reported significantly higher activity than non-Hispanic White or Hispanic women, but differences did not persist across pregnancy. Across gestation nulliparous women reported significantly lower activity than parous women. Women with singleton gestations reported significantly more activity than women with twins from weeks 26 to 38. Baseline activity level was strongly associated with later activity levels. CONCLUSIONS: Measuring domains of activity beyond exercise, and collecting longitudinal measurements, is necessary to fully describe activity in diverse populations of pregnant women.

Factors Associated With Quitting Smoking During Pregnancy Among Women Veterans.

INTRODUCTION: Little is known about the rates of smoking among pregnant veterans. Our objective was to examine rates of smoking during pregnancy and factors associated with quitting smoking during pregnancy. METHODS: We used data from a cohort study of pregnant veterans from 15 Veterans Health Administration facilities nationwide. Veterans who reported smoking during pregnancy were included in this analysis. Poisson regression models were used to estimate the relative risk (RR) of quitting smoking during pregnancy. RESULTS: Overall, 133 veterans reported smoking during pregnancy. Among this group of women who smoked, the average age was 31.6 years, 20% were Black, and 14% were Hispanic/Latino. More than one-half of women (65%) who reported smoking at the start of pregnancy quit smoking during pregnancy. Multivariable models, adjusted for history of deployment and age, indicated that prenatal care initiation at 12 or fewer weeks compared with more than 13 weeks (relative risk [RR], 2.06; 95% confidence interval [CI], 1.18-3.58), living without household smokers compared with any household smokers (RR, 1.58; 95% CI, 1.14-2.17), and first pregnancy (RR, 1.51; 95% CI, 1.17-1.95) were significant predictors of quitting versus persistent smoking during pregnancy. CONCLUSIONS: Women veterans who quit smoking may be different than those who continue to smoke during pregnancy. Establishing prenatal care early in pregnancy, which likely includes counseling about smoking cessation, seems to be an important factor in quitting. Those for whom it is not a first pregnancy and who live with other smokers may especially benefit from such counseling.

Physical activity and incidence of subclinical and clinical pregnancy loss: a secondary analysis in the effects of aspirin in gestation and reproduction randomized trial.

OBJECTIVE: To estimate the association between physical activity and risk of subclinical and clinical pregnancy loss among women with a history of pregnancy loss. DESIGN: Prospective cohort study as a secondary analysis of the Effects of Aspirin in Gestation and Reproduction randomized controlled trial of preconception-initiated low-dose aspirin among women with one or two prior pregnancy losses. SETTING: Four U.S. clinical centers, 2007-2011. PATIENT(S): Women with confirmed pregnancy (n = 785) as determined from hCG testing in longitudinally collected biospecimens. MAIN OUTCOME MEASURE(S): Subclinical loss of pregnancy detected only by hCG testing and clinically recognized loss. RESULT(S): Among 785 women (mean [SD] age, 28.7 [4.6] years) with an hCG-confirmed pregnancy, 188 (23.9%) experienced pregnancy loss. In multivariable models adjusted for confounders, compared with the first tertile of physical activity (median = 7.7 metabolic equivalent of task hours/week), there was a roughly twofold higher risk of subclinical loss in the second (risk ratio = 2.06; 95% confidence interval, 1.03-4.14) and third tertiles (risk ratio = 1.92; 95% confidence interval, 0.94-3.90), with median metabolic equivalent of task hours/week of 27.8 and 95.7, respectively. No relations were observed between physical activity and clinically recognized loss. CONCLUSION(S): Risk related to physical activity is different for pregnancy failure close to the time of implantation compared with that for later, clinical pregnancy loss. Higher physical activity levels were associated with an elevated risk of subclinical loss (i.e., pregnancies detected only by hCG, n = 55); however, no relationship was observed with clinically recognized loss. Further work is required to confirm these findings, assess generalizability to women without prior losses, and evaluate mechanisms. ETHICAL APPROVAL: Each participating center's Institutional Review Board approved the study, and participants provided written informed consent. The trial was registered on ClinicalTrials.gov (NCT00467363), and a Data Safety and Monitoring Board provided oversight.

Firefighter protective clothing and self contained breathing apparatus does not alter balance testing using a standard sensory organization test or motor control test in healthy, rested individuals.

BACKGROUND: There is a high rate of injury associated with firefighting: in 2016, 21% of all fireground injuries were attributed to falls, jumps and slips. Examining factors related to balance, including experience in wearing firefighter gear, may assist in reducing injury related to falls. OBJECTIVES: To assess the effects of wearing firefighter gear on postural balance in firefighters and non-firefighters in a rested condition. METHODS: Each subject attended two sessions. In session 1, informed consent was obtained, a threshold audiogram was collected, and the sensory organization test (SOT) and motor control test (MCT) were administered with the subject dressed in street clothes. The second session was comprised of three different conditions with the order of testing randomized across subjects: street clothing, firefighter protective garments (coat, pants, helmet, hood) with breathing apparatus but no facemask, and firefighter protective garments with breathing apparatus and facemask. Twenty subjects participated: ten firefighters (8 males) and sex and age-matched non-firefighters (8 males) completed the study. RESULTS: SOT scores were obtained for each sub-condition, including the overall performance score and sensory weightings. For the MCT, latency and amplitude data were obtained for the three forward and three reverse translation conditions. A significant difference was found for large forward surface translations in the MCT in firefighters. CONCLUSION: In spite of the altered center of balance created by breathing apparatus and the altered visual cues created by the facemask, wearing firefighter gear did not substantively affect anterior-posterior postural stability or motor response to linear translation in rested, healthy individuals. Firefighters and non-firefighters performed similarly across all except one of the experimental conditions.

Cold water submersion attenuates post-submersion aerobic performance and orthostatic tolerance irrespective of partial rehydration with water.

Purpose: This study examined the independent effects of cold-water submersion and a rehydration strategy on an aerobic endurance performance and orthostatic tolerance following a four-hour dive in cold water (10°C). Methods: Nine male subjects completed a control (CON) performance and lower-body negative pressure test (LBNP) and two water immersion visits with either no rehydration (NR) or a post-immersion rehydration (RH) with 1 L of water. Following submersion, subjects ran to exhaustion and submitted to LBNP. Results: Core body temperature declined during submersion and remained reduced from baseline until the run (P ⟨ 0.001) and was not different between NR and RH (P = 0.13). Total urine output during submersion was not different between groups (1.69 ± 0.49 (NR), 1.75 ± 0.52 (RH) L; P = 0.74) eliciting a body mass reduction of -2.2 ± 0.3 and -0.8 ±; 0.3% (P ⟨ 0.01), respectively. Run duration was not different (547 ± 141 (NR), 566 ± 152 (RH) s; P = 0.79); however, both NR and RH run duration was shorter compared to CON (722 ± 170 s; P = 0.04). Cumulative stress index was suppressed in NR (534 ± 163 mmHg*min) and RH (591 ± 129 mmHg*min) compared to CON (707 ± 170 mmHg*min, P V#8804; 0.03), with no differences between submersion trials (P = 0.23). Conclusion: Compared to a non-submersed state, run duration and orthostatic tolerance was reduced following a four-hour cold-water submersion. Rehydration with 1 L of water following submersion did not offer a performance advantage over no rehydration.

Reporting of Patient Experience Data on Health Systems' Websites and Commercial Physician-Rating Websites: Mixed-Methods Analysis.

BACKGROUND: Some hospitals' and health systems' websites report physician-level ratings and comments drawn from the Consumer Assessment of Healthcare Providers and Systems surveys. OBJECTIVE: The aim was to examine the prevalence and content of health system websites reporting these data and compare narratives from these sites to narratives from commercial physician-rating sites. METHODS: We identified health system websites active between June 1 and 30, 2016, that posted clinician reviews. For 140 randomly selected clinicians, we extracted the number of star ratings and narrative comments. We conducted a qualitative analysis of a random sample of these physicians' narrative reviews and compared these to a random sample of reviews from commercial physician-rating websites. We described composite quantitative scores for sampled physicians and compared the frequency of themes between reviews drawn from health systems' and commercial physician-rating websites. RESULTS: We identified 42 health systems that published composite star ratings (42/42, 100%) or narratives (33/42, 79%). Most (27/42, 64%) stated that they excluded narratives deemed offensive. Of 140 clinicians, the majority had composite scores listed (star ratings: 122/140, 87.1%; narrative reviews: 114/140, 81.4%), with medians of 110 star ratings (IQR 42-175) and 25.5 (IQR 13-48) narratives. The rating median was 4.8 (IQR 4.7-4.9) out of five stars, and no clinician had a score less than 4.2. Compared to commercial physician-rating websites, we found significantly fewer negative comments on health system websites (35.5%, 76/214 vs 12.8%, 72/561, respectively; P<.001). CONCLUSIONS: The lack of variation in star ratings on health system sites may make it difficult to differentiate between clinicians. Most health systems report that they remove offensive comments, and we notably found fewer negative comments on health system websites compared to commercial physician-rating sites.

Impact of shift duration on alertness among air-medical emergency care clinician shift workers.

BACKGROUND: Greater than half of Emergency Medical Services (EMS) shift workers report fatigue at work and most work long duration shifts. We sought to compare the alertness level of EMS shift workers by shift duration. METHODS: We used a multi-site, 14-day prospective observational cohort study design of EMS clinician shift workers at four air-medical EMS organizations. The primary outcome was behavioral alertness as measured by psychomotor vigilance tests (PVT) at the start and end of shifts. We stratified shifts by duration (< 24 h and 24 h), night versus day, and examined the impact of intra-shift napping on PVT performance. RESULTS: One hundred and twelve individuals participated. The distribution of shifts <24 h and 24 h with complete data were 54% and 46%, respectively. We detected no differences in PVT performance measures stratified by shift duration (P > 0.05). Performance for selected PVT measures (lapses and false starts) was worse on night shifts compared to day shifts (P < 0.05). Performance also worsened with decreasing time between waking from a nap and the end of shift PVT assessment. CONCLUSIONS: Deficits in performance in the air-medical setting may be greatest during night shifts and proximal to waking from an intra-shift nap. Future research should examine alertness and performance throughout air-medical shifts, as well as investigate the timing and duration of intra-shift naps on outcomes.

Physical Activity and Risk of Cesarean Delivery in Hispanic Women.

BACKGROUND: Rates of cesarean delivery continue to increase among Hispanics, the largest minority group in the United States. Prior studies of the relationship between physical activity and cesarean delivery have been conflicting, limited by questionnaires not validated for pregnancy, and conducted primarily among non-Hispanic whites. METHODS: We evaluated this association among participants (n = 1313) in Proyecto Buena Salud, a prospective cohort of Hispanic women conducted from 2006 to 2011. Physical activity was measured via the Pregnancy Physical Activity Questionnaire. RESULTS: In total, 320 (24.4%) participants delivered via cesarean. In multivariable analyses, increasing levels of sedentary activity in mid/late pregnancy were associated with higher odds of cesarean delivery (odds ratio = 1.54; 95% confidence interval, 1.02-3.33; Ptrend = .05); however, there were no clear patterns between physical activity and cesarean delivery. When we repeated the analysis excluding planned cesarean deliveries (n = 126), high levels of prepregnancy moderate-intensity physical activity (odds ratio = 0.61; 95% confidence interval, 0.38-0.99) and increasing moderate-intensity physical activity in mid/late pregnancy (Ptrend = .03) were associated with reduction in odds. Increasing levels of household/caregiving physical activity in pre and mid/late pregnancy were associated with a 50% reduction in odds (Ptrend < .05). CONCLUSIONS: In this prospective cohort of Hispanics, sedentary activity increased odds of cesarean delivery, and moderate-intensity and household/caregiving physical activity reduced odds of unplanned cesarean deliveries.

Real-Time Fatigue Mitigation with Air-Medical Personnel: The SleepTrackTXT2 Randomized Trial.

Objective: The aims of this study were: 1) to determine the short-term impact of the SleepTrackTXT2 intervention on air-medical clinician fatigue during work shifts and 2) determine the longer-term impact on sleep quality over 120 days. Methods: We used a multi-site randomized controlled trial study design with a targeted enrollment of 100 (ClinicalTrials.gov NCT02783027). The intervention was behavioral (non-pharmacological) and participation was scheduled for 120 days. Participation was voluntary. All consented participants answered baseline as well as follow-up surveys. All participants answered text message queries, which assessed self-rated fatigue, sleepiness, concentration, recovery, and hours of sleep. Intervention participants received additional text messages with recommendations for behaviors that can mitigate fatigue. Intervention participants received weekly text messages that promoted sleep. Our analysis was guided by the intent-to-treat principle. For the long-term outcome of interest (sleep quality at 120 days), we used a two-sample t-test on the change in sleep quality to determine the intervention effect. Results: Eighty-three individuals were randomized and 2,828 shifts documented (median shifts per participant =37, IQR 23-49). Seventy-one percent of individuals randomized (n = 59) participated up to the 120-day study period and 52% (n = 43) completed the follow-up survey. Of the 69,530 text messages distributed, participants responded to 61,571 (88.6%). Mean sleep quality at 120 days did not differ from baseline for intervention (p > 0.05) or control group participants (p > 0.05), and did not differ between groups (p > 0.05). There was no change from baseline to 120 days in the proportion with poor sleep quality in either group. Intra-shift fatigue increased (worsened) over the course of 12-hour shifts for participants in both study arms. Fatigue at the end of 12-hour shifts was higher among control group participants than participants in the intervention group (p < 0.05). Pre-shift hours of sleep were often less than 7 hours and did not differ between the groups over time. Conclusions: The SleepTrackTXT2 behavioral intervention showed a positive short-term impact on self-rated fatigue during 12-hour shifts, but did not impact longer duration shifts or have a longer-term impact on sleep quality among air-medical EMS clinicians.

Effect of rehydration schedule after four-hour head-out water immersion on running performance and recovery.

Introduction: Head-out water immersion (HOWI) results in diuresis, which could potentially limit performance after egress to land. We examined the effect of rehydration on endurance, cardiovascular stability, and overnight recovery following a four-hour thermoneutral HOWI on 12 subjects. Methods: Twelve males completed a crossover design consisting of no hydration, replacement of fluid loss during immersion (RD), and replacement of fluid after the immersion period (RA). Sixty minutes following immersion, subjects ran to exhaustion at ~80% maximum heart rate. After completing the run, each subject submitted to a head-up tilt test (HUTT). Vital signs and ECG were monitored overnight. Results: HOWI resulted in a transient diuresis in NH and RA, while it was sustained throughout immersion in the RD protocol, resulting in greater urine [l] output (1.27 ± 0.48 (NH), 1.18 ± 0.43 (RA), 2.32 ± 0.77 (RD) (p ⟨ 0.001). Body mass change (%) was greater in NH than RD, but not RA (-1.58 ± 0.56 (NH), -0.66 ± 0.47 (RD), and -0.92 ± 0.76 (RA)). Run times were 17% versus 20% in NH compared to RD and RA, respectively, but were not statistically different. Time to orthostasis during the HUTT did not differ by condition. Overnight heart rate variability and blood pressures were not different. Conclusion: Rehydration during water immersion resulted in a large, sustained diuresis without improving performance or recovery after exiting the water. Loss of body water during thermoneutral HOWI was modest, and both rehydration strategies minimally affected aerobic performance and overnight recovery in young, healthy males.

A prospective study of physical activity and fecundability in women with a history of pregnancy loss.

STUDY QUESTION: Is physical activity (PA) associated with fecundability in women with a history of prior pregnancy loss? SUMMARY ANSWER: Higher fecundability was related to walking among overweight/obese women and to vigorous PA in women overall. WHAT IS KNOWN ALREADY: PA may influence fecundability through altered endocrine function. Studies evaluating this association have primarily utilized Internet-based recruitment and self-report for pregnancy assessment and have yielded conflicting results. STUDY DESIGN, SIZE, DURATION: This is a secondary analysis of the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial (2007-2011), a multisite, randomized controlled trial of preconception-initiated low-dose aspirin. PARTICIPANTS/MATERIALS, SETTING, METHODS: Healthy women (n = 1214), aged 18-40 and with 1-2 prior pregnancy losses, were recruited from four US medical centers. Participants were followed for up to six menstrual cycles while attempting pregnancy and through pregnancy for those who became pregnant. Time to hCG detected pregnancy was assessed using discrete-time Cox proportional hazard models to estimate fecundability odds ratios (FOR) adjusted for covariates, accounting for left truncation and right censoring. MAIN RESULTS AND THE ROLE OF CHANCE: The association of walking with fecundability varied significantly by BMI (P-interaction = 0.01). Among overweight/obese women, walking ≥10 min at a time was related to improved fecundability (FOR = 1.82, 95% CI: 1.19, 2.77). In adjusted models, women reporting >4 h/wk of vigorous activity had significantly higher fecundability (FOR = 1.69, 95% CI: 1.24, 2.31) compared to no vigorous activity. Associations of vigorous activity with fecundability were not significantly different by BMI (P-interaction = 0.9). Moderate activity, sitting, and International Physical Activity Questionnaire (IPAQ) categories were not associated with fecundability overall or in BMI-stratified analyses. LIMITATIONS, REASONS FOR CAUTION: Some misclassification of PA levels as determined by the short form of the IPAQ is likely to have occurred, and may have led to non-differential misclassification of exposure in our study. Information on diet and change in BMI was not collected and may have contributed to some residual confounding in our results. The generalizability of our results may be limited as our population consisted of women with a history of one or two pregnancy losses. WIDER IMPLICATIONS OF THE FINDINGS: These findings provide positive evidence for the benefits of PA in women attempting pregnancy, especially for walking among those with higher BMI. Further study is necessary to clarify possible mechanisms through which walking and vigorous activity might affect time-to-pregnancy. STUDY FUNDING/COMPETING INTEREST(S): This work was funded by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The authors report no conflicts of interest in this work. TRIAL REGISTRATION NUMBER: #NCT00467363.

Fatigue mitigation with SleepTrackTXT2 in air medical emergency care systems: study protocol for a randomized controlled trial.

BACKGROUND: Most air medical Emergency Medical Services (EMS) clinicians work extended duration shifts, and more than 50% report inadequate sleep, poor sleep quality, and/or poor recovery between shifts. The SleepTrackTXT pilot trial (ClinicalTrials.gov, NCT02063737) showed that use of mobile phone text messages could impact EMS clinician self-reported fatigue and sleepiness during long duration shifts. The purpose of the SleepTrackTXT2 trial is to leverage lessons learned from the first SleepTrackTXT study and test an enhanced intervention targeting air medical EMS clinicians. METHODS/DESIGN: We will conduct a multi-site randomized trial with a sample of adult EMS clinicians recruited from four air medical EMS systems located in the midwest, northeastern, and southern USA. Participants will be allocated to one of two possible arms for a 4-month (120-day) study period. The intervention arm will involve text-message assessments of sleepiness, fatigue, and difficulty concentrating at the beginning, every 4 hours during, and at the end of scheduled shifts. Participants reporting high levels of sleepiness, fatigue, or difficulty with concentration will receive one of nine randomly selected intervention messages to promote behavior change during shift work to improve alertness. Intervention participants will receive a text-message report on Friday of each week that shows their sleep debt over the previous 7 days followed by a text message to promote paying back sleep debt recovery when feasible. Participants in the control group receive text messages that only include assessments. Both arms will receive text-message assessments of perceived recovery since last shift, sleepiness, fatigue, or difficulty with concentration at noon (1200 hours) on days between scheduled shifts (off-duty days). We have two aims for this study: (1) to determine the short-term impact of the enhanced SleepTrackTXT2 intervention on air medical clinician fatigue reported in real time during and at the end of shift work, and (2) to determine the long-term impact of the SleepTrackTXT2 intervention on sleep quality and sleep health indicators including hours of sleep and recovery between shift work. DISCUSSION: The SleepTrackTXT2 trial may provide evidence of real-world effectiveness that would support widespread expansion of fatigue mitigation interventions in emergency care clinician shift workers. The trial may specifically support use of real-time assessments and interventions delivered via mobile technology such as text messaging. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02783027 . Registered on 23 May 2016.

Firefighter Work Duration Influences the Extent of Acute Kidney Injury.

PURPOSE: We tested the hypothesis that elevations in biomarkers of acute kidney injury are influenced by the magnitude of hyperthermia and dehydration elicited by two common firefighter work durations. METHODS: Twenty-nine healthy adults (10 females) wearing firefighter protective clothing completed two randomized trials where they walked at 4.8 km·h, 5% grade in a 38°C, 50% RH environment. In the short trial, subjects completed two 20-min exercise bouts. In the long trial (LONG), subjects completed three 20-min exercise bouts. Each exercise bout was separated by 10 min of standing rest in an ~20°C environment. Venous blood samples were obtained before and immediately after exercise, and after 1 h recovery. Dependent variables included changes in core temperature, body weight, plasma volume, serum creatinine, and plasma neutrophil gelatinase-associated lipocalin, a marker of renal tubule injury. RESULTS: Changes in core temperature (+2.0°C ± 0.7°C vs +1.1°C ± 0.4°C, P < 0.01), body weight (-0.9% ± 0.6% vs -0.5% ± 0.5%, P < 0.01), and plasma volume (-11% ± 5% vs -8% ± 6%, P < 0.01) during exercise were greater in LONG. Increases in creatinine were higher in LONG postexercise (0.18 ± 0.15 vs 0.08 ± 0.07 mg·dL, P < 0.01) and after recovery (0.21 ± 0.16 vs 0.14 ± 0.10 mg·dL, P < 0.01). Increases in neutrophil gelatinase-associated lipocalin were greater in LONG postexercise (27.0 ± 20.5 vs 12.7 ± 18.0 ng·mL, P = 0.01) and after recovery (16.9 ± 15.6 vs 1.5 ± 15.1 ng·mL, P = 0.02). CONCLUSIONS: Biomarkers of acute kidney injury are influenced by the magnitude of hyperthermia and hypovolemia elicited by exercise in the heat.

Physical activity interventions in pregnancy and risk of gestational diabetes mellitus: a systematic review and meta-analysis.

OBJECTIVE: Gestational diabetes mellitus (GDM) is a common complication of pregnancy associated with an increased incidence of pregnancy complications, adverse pregnancy outcomes, and maternal and fetal risks of chronic health conditions later in life. Physical activity has been proposed to reduce the risk of GDM and is supported by observational studies, but experimental research assessing its effectiveness is limited and conflicting. We aimed to use meta-analysis to synthesize existing randomized controlled studies of physical activity and GDM. DATA SOURCES: We searched MEDLINE, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov for eligible studies. METHODS OF STUDY SELECTION: The following combination of keywords was used: (pregnant or pregnancy or gestation or gestate or gestational or maternity or maternal or prenatal) AND (exercise or locomotion or activity or training or sports) AND (diabetes or insulin sensitivity or glucose tolerance) AND (random* or trial). Eligibility was restricted to studies that randomized participants to an exercise-only-based intervention (ie, separate from dietary interventions) and presented data regarding GDM risk. Two authors performed the database search, assessment of eligibility, and abstraction of data from included studies, and a third resolved any discrepancies. A total of 469 studies was retrieved, of which 10 met inclusion criteria and could be used for analysis (3,401 participants). TABULATION, INTEGRATION, AND RESULTS: Fixed-effects models were used to estimate summary relative risk (RR) and 95% confidence interval (CI) and I to assess heterogeneity. There was a 28% reduced risk (95% CI 9-42%) in the intervention group compared with the control group (RR 0.72, P=.005). Heterogeneity was low (I=12%) and nonsignificant (P=.33). CONCLUSION: The results from this meta-analysis suggest that physical activity in pregnancy provides a slight protective effect against the development of GDM. Studies evaluating type, timing, duration, and compliance of physical activity regimens are warranted to best inform obstetric guidelines.