Water aerobics II: maternal body composition and perinatal outcomes after a program for low risk pregnant women The effects of maternal aerobic exercise on human placental development: placental volumetric composition and surface areas. Is recreational running associated with earlier delivery and lower birth weight in women who continue to run during pregnancy? An international retrospective cohort study of running habits of 1293 female runners during pregnancy Antepartum, Intrapartum, and Neonatal Significance of Exercise on Healthy Low‐Risk Pregnant Working Women The Effect of Vigorous Exercise During Pregnancy on Birth‐Weight The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials Nutrition and exercise reduce excessive weight gain in normal-weight pregnant women. A randomized clinical trial of exercise during pregnancy to prevent gestational diabetes mellitus and improve pregnancy outcome in overweight and obese pregnant women A 12-Week Exercise Program for Pregnant Women with Obesity to Improve Physical Activity Levels: An Open Randomised Preliminary Study Physical activity during pregnancy and infant’s birth weight: results from the 3D Birth Cohort Walking program of low or vigorous intensity during pregnancy confers an aerobic benefit. Risk factors for small‐for‐gestational‐age infants by customised birthweight centiles: data from an international prospective cohort study Beginning regular exercise in early pregnancy: effect on fetoplacental growth. Physical Activity and Risk of Small-for-Gestational-Age Birth Among Predominantly Puerto Rican Women Exercise during pregnancy and pregnancy outcome. Moderate and Vigorous Intensity Exercise During Pregnancy and Gestational Weight Gain in Women with Gestational Diabetes Exercise training in pregnancy reduces offspring size without changes in maternal insulin sensitivity. Continuing regular exercise during pregnancy: effect of exercise volume on fetoplacental growth.
Background To evaluate the effectiveness and safety of water aerobics during pregnancy . Methods A r and omized controlled trial carried out in 71 low-risk sedentary pregnant women , r and omly allocated to water aerobics or no physical exercise .  Maternal body composition and perinatal outcomes were evaluated . For statistical analysis Chi-square , Fisher 's or Student 's t-tests were applied . Risk ratios and their 95 % CI were estimated for main outcomes . Body composition was evaluated across time using MANOVA or Friedman multiple analysis . Results There were no significant differences between the groups regarding maternal weight gain , BMI or percentage of body fat during pregnancy . Incidence of preterm births ( RR = 0.84 ; 95%CI:0.28–2.53 ) , vaginal births ( RR = 1.24 ; 95%CI:0.73–2.09 ) , low birthweight ( RR = 1.30 ; 95%CI:0.61–2.79 ) and adequate weight for gestational age ( RR = 1.50 ; 95%CI:0.65–3.48 ) were also not significantly different between groups . There were no significant differences in systolic and diastolic blood pressure and heart rate between before and immediately after the water aerobics session . Conclusion Water aerobics for sedentary pregnant women proved to be safe and was not associated with any alteration in maternal body composition , type of delivery , preterm birth rate , neonatal well-being or weight The histomorphometry of term placentae from women who exercised regularly throughout either the first half or all of pregnancy was compared to that of placentae from matched controls to determine if regular exercise during pregnancy produced histomorphometric evidence of altered development and transport capacity . Conventional stereological techniques were used to estimate placental volumetric composition , surface areas , and villous and vascular configurations in the three groups . Exercise confined to early pregnancy increased the parenchymal component of the placenta , total vascular volume and site-specific capillary volume and surface area .  Exercise throughout pregnancy increased these and multiple other histomorphometric parameters associated with the rate of placental perfusion and transfer function . However , significant changes were confined to villi > 80 microns in diameter . The localization of both the timing of the stimulus and the anatomical sites affected indicates that regular , sustained exercise modifies placental development primarily in early and mid-pregnancy . We speculate that the lack of significant changes in the structure and configuration of the smaller villi indicates that other adaptive mechanisms , such as increased rates of placental blood flow , must be well developed by the latter portion of the mid-trimester and adequately maintain fetal oxygenation and substrate delivery throughout the third trimester Background Increasingly , women of reproductive age participate in recreational running , but its impact on pregnancy outcome is unknown . We investigated whether running affects gestational age at delivery and birth weight as indicators of cervical integrity and placental function , respectively . Methods 1293 female participants were recruited from parkrun , which organises weekly runs involving 1.25 million runners across 450 parks worldwide . Those under 16 or unable to provide outcome data were excluded . Women were categorised according to whether they continued to run during pregnancy or not . Those who continued were further stratified dependent on average weekly kilometres , and which trimester they ran until . Retrospectively collected primary outcomes were gestational age at delivery and birthweight centile . Other outcomes included assisted vaginal delivery rate and prematurity at clinical ly important gestations . Results There was no significant difference in gestational age at delivery : 279.0 vs 279.6 days ( mean difference 0.6 days , CI −1.3 to 2.4 days ; P=0.55 ) or birthweight centile : 46.9%vs 44.9 % ( mean difference 2.0 % , CI −1.3 % to −5.3 % ; P=0.22 ) in women who stopped running and those who continued , respectively . Assisted vaginal delivery rate was increased in women who ran : 195/714 ( 27 % ) vs 128/579 ( 22 % ) ( OR 1.32 ; CI 1.02 to 1.71 ; P=0.03 ) . Conclusion Continuing to run during pregnancy does not appear to affect gestational age or birthweight centile , regardless of mean weekly distance or stage of pregnancy . Assisted vaginal delivery rates were higher in women who ran , possibly due to increased pelvic floor muscle tone . R and omised prospect i ve analysis is necessary to further explore these findings OBJECTIVE To evaluate the influence of exercise on maternal and perinatal outcome in a low‐risk healthy obstetric population . METHODS We conducted a prospect i ve observational study of low‐risk healthy women exercising during their pregnancy . An extensive question naire collected antepartum , intrapartum , and postpartum patient information on 750 women . The women were divided into four groups based on exercise level during pregnancy . RESULTS There were no differences among groups for maternal demographic characteristics , antenatal illnesses , stress , social support , or smoking . Heavily exercising women were older ( P = .042 ) , had higher incomes ( P = .001 ) , and were exercising more at conception ( P = .001 ) . Women who did more exercise were more likely to need an induction of labor ( P = .033 , relative risk 1.84 , 95 % confidence interval 1.05 , 3.20 ) , induction or augmentation with oxytocin ( P = .015 , relative risk 1.53 , 95 % confidence interval 1.19 , 1.97 ) , and had longer first‐stage labors ( P = .032 ) result ing in longer total labors ( P = .011 ) . The difference in the length of first‐stage labor was even greater if the no‐exercise group was compared with the strongly exercising group ( P = .009 , relative risk 1.38 , 95 % confidence interval 0.16 , 2.60 ) . Fewer umbilical cord abnormalities ( P = .034 ) were observed with exercise , but exercising women had more colds and flu ( P = .008 ) . Heavily exercising women had smaller infants ( mean difference 86.5 g ) compared with sedentary women . CONCLUSION Exercise  in working women is associated with smaller babies , increased number of inductions and augmentations of labor , and longer labors . Colds and flu are more frequent in exercising women EDITORIAL COMMENT : When this paper was review ed the question was raised that the period of gestation is an obvious factor which can determine birth‐weight and the authors were asked how this may have affected their results The authors response was as follows Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more PURPOSE This study aim ed to evaluate the effect of an exercise program of two different intensities , with nutritional control , on gestational weight gain ( GWG ) , infant birth weight , and maternal weight retention at 2 months postpartum ( 2 mopp ) . METHODS Pregnant women ( prepregnancy body mass index = 18.5 - 24.9 kg·m ) were r and omized at study entry ( 16 - 20 wk of gestation ) to a low-intensity ( LI , 30 % HR reserve ( HRR ) , n = 23 ) or moderate-intensity ( MI , 70 % HRR , n = 26 ) exercise program , with nutritional control . The exercise program consisted of walking sessions three to four times per week , gradually increasing exercise time from 25 to 40 min per session . Forty-five normal-weight women who did not participate in any structured exercise program during pregnancy and had singleton births were used as a historical control group .  RESULTS Total GWG was higher in the control group ( 18.3 ± 5.3 kg ) compared with the LI ( 15.3 ± 2.9 kg , P = 0.01 ) and MI ( 14.9 ± 3.8 kg , P = 0.003 ) groups . During the intervention , GWG was similar in both intervention groups , with weekly rates of weight gain of 0.49 ± 0.1 and 0.47 ± 0.1 kg·wk in the LI and MI groups , respectively . Excessive GWG during the intervention was prevented in 70 % of the women in the LI group and 77 % of those in the MI group . Excessive GWG occurred before the intervention began . At 2 mopp , 18 % and 28 % of the women in the LI and MI groups , respectively , retained ≤2.0 kg compared with only 7 % of those in the control group . Infant birth weight was not different between the groups . CONCLUSIONS Results suggest that a prenatal nutrition and exercise program regardless of exercise intensity , reduced excessive GWG and decreased weight retention at 2 mopp in women of normal weight before pregnancy BACKGROUND : Obesity and being overweight are becoming epidemic , and indeed , the proportion of such women of reproductive age has increased in recent times . Being overweight or obese prior to pregnancy is a risk factor for gestational diabetes mellitus , and increases the risk of adverse pregnancy outcome for both mothers and their offspring . Furthermore , the combination of gestational diabetes mellitus with obesity/overweight status may increase the risk of adverse pregnancy outcome attributable to either factor alone . Regular exercise has the potential to reduce the risk of developing gestational diabetes mellitus and can be used during pregnancy ; however , its efficacy remain controversial . At present , most exercise training interventions are implemented on Caucasian women and in the second trimester , and there is a paucity of studies focusing on overweight/obese pregnant women . OBJECTIVE : We sought to test the efficacy of regular exercise in early pregnancy to prevent gestational diabetes mellitus in Chinese overweight/obese pregnant women . STUDY DESIGN : This was a prospect i ve r and omized clinical trial in which nonsmoking women age > 18 years with a singleton pregnancy who met the criteria for overweight/obese status ( body mass index 24≤28 kg/m2 ) and had an uncomplicated pregnancy at < 12 + 6 weeks of gestation were r and omly allocated to either exercise or a control group . Patients did not have contraindications to physical activity . Patients allocated to the exercise group were assigned to exercise 3 times per week ( at least 30 min/session with a rating of perceived exertion between 12‐14 ) via a cycling program begun within 3 days of r and omization until 37 weeks of gestation . Those in the control group continued their usual daily activities . Both groups received st and ard prenatal care , albeit without special dietary recommendations . The primary outcome was incidence of gestational diabetes mellitus . RESULTS : From December 2014 through July 2016 , 300 singleton women at 10 weeks ’ gestational age and with a mean prepregnancy body mass index of 26.78 ± 2.75 kg/m2 were recruited . They were r and omized into an exercise group ( n = 150 ) or a control group ( n = 150 ) . In all , 39 ( 26.0 % ) and 38 ( 25.3 % ) participants were obese in each group , respectively . Women r and omized to the exercise group had a significantly lower incidence of gestational diabetes mellitus ( 22.0 % vs 40.6 % ; P < .001 ) . These women also had significantly less gestational weight gain by 25 gestational weeks ( 4.08 ± 3.02 vs 5.92 ± 2.58 kg ; P < .001 ) and at the end of pregnancy ( 8.38 ± 3.65 vs 10.47 ± 3.33 kg ; P < .001 ) , and reduced insulin resistance levels ( 2.92 ± 1.27 vs 3.38 ± 2.00 ; P = .033 ) at 25 gestational weeks . Other secondary outcomes , including gestational weight gain between 25‐36 gestational weeks ( 4.55 ± 2.06 vs 4.59 ± 2.31 kg ; P = .9 ) , insulin resistance levels at 36 gestational weeks ( 3.56 ± 1.89 vs 4.07 ± 2.33 ; P = .1 ) , hypertensive disorders of pregnancy ( 17.0 % vs 19.3 % ; odds ratio , 0.854 ; 95 % confidence interval , 0.434–2.683 ; P = .6 ) , cesarean delivery ( except for scar uterus ) ( 29.5 % vs 32.5 % ; odds ratio , 0.869 ; 95 % confidence interval , 0.494–1.529 ; P = .6 ) , mean gestational age at birth ( 39.02 ± 1.29 vs 38.89 ± 1.37 weeks ’ gestation ; P = .5 ) ; preterm birth ( 2.7 % vs 4.4 % , odds ratio , 0.600 ; 95 % confidence interval , 0.140–2.573 ; P = .5 ) , macrosomia ( defined as birthweight > 4000 g ) ( 6.3 % vs 9.6 % ; odds ratio , 0.624 ; 95 % confidence interval , 0.233–1.673 ; P = .3 ) , and large‐for‐gestational‐age infants ( 14.3 % vs 22.8 % ; odds ratio , 0.564 ; 95 % confidence interval , 0.284–1.121 ; P = .1 ) were also lower in the exercise group compared to the control group , but without significant difference . However , infants born to women following the exercise intervention had a significantly lower birthweight compared with those born to women allocated to the control group ( 3345.27 ± 397.07 vs 3457.46 ± 446.00 g ; P = .049 ) . CONCLUSION : Cycling exercise initiated early in pregnancy and performed at least 30 minutes , 3 times per week , is associated with a significant reduction in the frequency of gestational diabetes mellitus in overweight/obese pregnant women . And this effect is very relevant to that exercise at the beginning of pregnancy decreases the gestational weight gain before the mid‐second trimester . Furthermore , there was no evidence that the exercise prescribed in this study increased the risk of preterm birth or reduced the mean gestational age at birth Objective To evaluate whether a 12-week supervised exercise program promotes an active lifestyle throughout pregnancy in pregnant women with obesity . Methods In this preliminary r and omised trial , pregnant women ( body mass index ≥ 30 kg/m2 ) were allocated to either  st and ard care or supervised training , from 15 to 27 weeks of gestation . Physical activity was measured by accelerometry at 14 , 28 and 36 weeks , while fitness ( oxygen consumption ( VO2 ) at the anaerobic threshold ) , nutrition ( caloric intake and macronutrients percentage ) and anthropometry were assessed at 14 and 28 weeks of gestation . Analyses were performed using repeated measures ANOVA . Results A total of fifty ( 50 ) women were r and omised , 25 in each group . There was no time-group interaction for time spent at moderate and vigorous activity ( pinteraction = 0.064 ) , but the exercise group ’s levels were higher than controls ’ at all times ( pgroup effect = 0.014 ) . A significant time-group interaction was found for daily physical activity ( p = 0.023 ) ; similar at baseline ( ( 22.0 ± 6.7 vs 21.8 ± 7.3 ) x 104 counts/day ) the exercise group had higher levels than the control group following the intervention ( ( 22.8 ± 8.3 vs 19.2 ± 4.5 ) x 104 counts/day , p = 0.020 ) and at 36 weeks of gestation ( ( 19.2 ± 1.5 vs 14.9 ± 1.5 ) x 104 counts/day , p = 0.034 ) . Exercisers also gained less weight than controls during the intervention period despite similar nutritional intakes ( difference in weight change = -0.1 kg/week , 95 % CI -0.2 ; -0.02 , p = 0.016 ) and improved cardiorespiratory fitness ( difference in fitness change = 8.1 % , 95 % CI 0.7 ; 9.5 , p = 0.041 ) . Conclusions Compared with st and ard care , a supervised exercise program allows pregnant women with obesity to maintain fitness , limit weight gain and attenuate the decrease in physical activity levels observed in late pregnancy . Trial Registration Clinical Trials.gov Aim To evaluate the association between  maternal physical activity and  infant ’s birth weight or risk of inappropriate weight for gestational age ( GA )  , and whether this association differs by infant ’s sex , maternal body mass index ( BMI ) or pregnancy complications in a prospect i ve cohort study . Methods 1913 pregnant women from the 3D Birth Cohort ( Québec , Canada ) completed the  Pregnancy Physical Activity Question naire at each trimester . Energy expenditure ( metabolic equivalent of task (MET)*hours/week ) for total activity , sports and exercise and vigorous intensity activities was calculated . The associations with birth weight and risk of inappropriate weight for GA were evaluated by regression modelling . Interactions were tested with infant ’s sex , maternal prepregnancy BMI , gestational diabetes , hypertensive disorders and prematurity . Results Each 1 MET/hours/week increase in sports and exercise in the first trimester was associated with a 2.5 g reduction in infant ’s birth weight ( 95 % CI −4.8 to −0.3 ) but was not associated with the risk of small weight for GA . In contrast , although not significant , a 17 % reduction in the risk of large weight for GA was observed with increasing sports and exercise . Furthermore , in women with subsequent pre-eclampsia ( but not normotensive or hypertensive women ) , each 1 MET/hours/week increment spent in any vigorous exercise in the first trimester reduced the infant ’s birth weight by 19.8 g ( 95 % CI −35.2 to −4.3 ) . Conclusions Pregnant women with higher sports and exercise levels in the first trimester delivered infants with a lower birth weight . The risk of reducing infant ’s birth weight with vigorous exercise in women who develop pre-eclampsia later in pregnancy requires evaluation Walking is the most popular activity during pregnancy and may confer an aerobic benefit . However , the minimum intensity threshold of a maternal walking program for an aerobic conditioning response is unknown . The purpose was to examine the effect of a walking program of a low-intensity ( LI , 30 % heart rate reserve , HRR ) or vigorous-intensity ( VI , 70%HRR ) on maternal cardiorespiratory responses to a st and ard submaximal treadmill test . Normal weight pregnant women were r and omized at study entry ( 16 - 20 weeks of gestation ) to the LI ( n=23 ) or VI ( n=21 ) walking program  , with nutritional control . Participants performed a steady-state treadmill exercise test at their prescribed intensity pre- and post-intervention ( 34 - 36 weeks ) to evaluate changes in cardiorespiratory responses . Increasing body mass due to pregnancy was similar between the groups throughout the study . From pre- to post-intervention , relative ( mL kg - 1 min - 1 ) VO2 and VCO2 during steady-state submaximal treadmill exercise did not change in the LI group but decreased in the VI group ( - 1.25±2.71 , p=0.02 and - 1.50±2.64 , p=0.005 , respectively ) . Both groups presented increases in oxygen pulse ( p≤0.002 ) . Our results showed that the energy cost of walking was not affected by the increase in maternal body weight in the LI group and was decreased in the VI group , suggesting an aerobic conditioning response in both groups , although the VI group presented a greater response . All women presented similar body mass throughout the intervention and delivered healthy babies , indicating that a prenatal walking program of low or vigorous intensity , combined with healthy eating habits , is safe and beneficial to the mother and fetus Please cite this paper as : McCowan L , Roberts C , Dekker G , Taylor R , Chan E , Kenny L , Baker P , Moss‐Morris R , Chappell L , North R on behalf of the SCOPE consortium . Risk factors for small‐for‐gestational‐age infants  by customised birthweight centiles : data from an international prospect i ve cohort study . BJOG 2010;117:1599–1607 OBJECTIVE Our purpose was to test the null hypothesis that beginning regular , moderate-intensity exercise in early pregnancy has no effect on fetoplacental growth . STUDY DESIGN Forty-six women who did not exercise regularly were r and omly assigned at 8 weeks either to no exercise ( n = 24 ) or to weight-bearing exercise ( n = 22 ) 3 to 5 times a week for the remainder of pregnancy . Outcome variables included antenatal placental growth rate and neonatal and placental morphometric measurements . RESULTS The offspring of the exercising women were significantly heavier ( corrected birth weight : 3.75 + /- 0.08 kg vs 3.49 + /- 0.07 kg ) and longer ( 51.8 + /- 0.3 cm vs 50.6 + /- 0.3 cm ) than those born to control women . The difference in birth weight was the result of an increase in both lean body mass and fat mass . In addition , midtrimester placental growth rate was faster ( 26 + /- 2 cm(3)/wk vs 21 + /- 1 cm(3)/wk ) and morphometric indexes of placental function were greater in the exercise group . There were no significant differences in neonatal percentage body fat , head circumference , ponderal index , or maternal weight gain . CONCLUSIONS These data indicate that beginning a moderate regimen of weight-bearing exercise in early pregnancy enhances fetoplacental growth To estimate the association between multiple domains of physical activity and risk of small-for-gestational-age ( SGA ) birth .  We utilized data from 1,040 participants in the Latina Gestational Diabetes Mellitus Study , a prospect i ve cohort of predominantly Puerto Rican prenatal care patients in Massachusetts .  Physical activity was assessed by bilingual interviewers using a modified version of the Kaiser physical activity survey in early ( mean = 15 weeks ) and mid pregnancy ( mean = 28 weeks ) .  Physical activity ( i.e. ,  sports/exercise , household , occupational , and active living )  in pre , early and mid pregnancy was categorized in quartiles . SGA was classified as < 10th percentile of birth weight for gestational age . Pre- and early-pregnancy physical activity were not associated with SGA . In multivariable analyses , women with high total activity in mid-pregnancy had a decreased risk of SGA [ risk ratio ( RR ) = 0.42 ; 95 % confidence interval ( CI ) 0.21–0.82 ; ptrend = 0.003 ] as compared to those with low total activity . Findings were similar for high household activity ( RR = 0.69 ; 95 % CI = 0.34–1.40 ; ptrend = 0.26 ) , active living ( RR = 0.63 ; 95 % CI = 0.35–1.13 ; ptrend = 0.04 ) , and occupational activity ( RR = 0.79 , 95 % CI = 0.47–1.34 ; ptrend = 0.26 ) . High levels of sports/exercise were associated with an increased SGA risk without a significant dose – response association ( RR = 2.14 , 95 % CI 1.04–4.39 ; ptrend = 0.33 ) . Results extend prior studies of physical activity and SGA to the Hispanic population To investigate the effects of participation in aerobic exercise on pregnancy outcome , 388 women ( mean age = 31.7 , range = 18 - 42 ) were followed from a mean 16.5-wk gestation through delivery . Frequency , duration , and mode of aerobic exercise prior to conception and during the first trimester were determined by in-person interviews . Activity patterns during the second and third trimesters were assessed by telephone interviews . For each time period , women were categorized into one of the following exercise groups : Level I = aerobic exercise , excluding vigorous walking , at least three times a week for at least 20 min a time ; Level II = aerobic exercise at least three times a week and 20 min at a time , if and only if vigorous walking is included ; Level III = aerobic exercise less than three times a week , 20 min a time ; and Level IV = aerobic exercise less than once a week .  Mean birthweight was statistically unrelated to level of exercise preconceptionally or in any trimester . Gestational age , weight gain , and other pregnancy outcomes were also unassociated with exercise level . However , pregnancy symptoms were inversely associated with level of exercise ; women who exercised more earlier in pregnancy reported fewer discomforts later in pregnancy ( P = 0.01 ) . These data suggest that participation in aerobic exercise during pregnancy at a level great enough to produce or maintain a training effect does not adversely affect birthweight or other maternal and infant outcomes but may be associated temporally with fewer perceived pregnancy-associated discomforts Objectives To estimate the associations of moderate and vigorous intensity exercise during pregnancy with the rate of gestational weight gain ( GWG ) from gestational diabetes ( GDM ) diagnosis to delivery , overall and stratified by prepregnancy overweight/obesity . Methods Prospect i ve cohort study with physical activity reported shortly after the GDM diagnosis and prepregnancy weight and post-diagnosis GWG obtained from electronic health records ( n = 1055 ) .  Multinomial logistic regression models in the full cohort and stratified by prepregnancy overweight/obesity estimated associations of moderate and vigorous intensity exercise with GWG below and above the Institute of Medicine ’s ( IOM ) prepregnancy BMI -specific recommended ranges for weekly rate of GWG in the second and third trimesters . Results In the full cohort , any participation in vigorous intensity exercise was associated with decreased odds of GWG above recommended ranges as compared to no participation [ odds ratio ( 95 % confidence interval ) : 0.63 ( 0.40 , 0.99 ) ] , with a significant trend for decreasing odds of excess GWG with increasing level of vigorous intensity exercise . Upon stratification by prepregnancy overweight/obesity , significant associations were only observed for BMI ≥ 25.0 kg/m2 : any vigorous intensity exercise , as compared to none , was associated with 54 % decreased odds of excess GWG [ 0.46 ( 0.27 , 0.79 ) ] and significant trends were detected for decreasing odds of GWG both below and above the IOM ’s recommended ranges with increasing level of vigorous exercise ( both P ≤ 0.03 ) . No associations were observed for moderate intensity exercise . Conclusions for Practice In women with GDM , particularly overweight and obese women  , vigorous intensity exercise during pregnancy may reduce the odds of excess GWG CONTEXT Epidemiological studies have identified the importance of the in utero environment in providing a healthy start to life . Previous studies have suggested that the maternal environment , in particular a reduction in maternal insulin sensitivity , contributes significantly to fetal growth . Regular aerobic exercise , through an effect on maternal insulin sensitivity , may influence offspring size by regulating nutrient supply to the fetus . OBJECTIVE The aim of the study was to determine the effects of aerobic exercise training in the second half of pregnancy on maternal insulin sensitivity and neonatal outcomes . DESIGN AND SETTING We conducted a community-based , r and omized , controlled trial of exercise in pregnancy . PARTICIPANTS Eighty-four healthy nulliparous women ( mean + /- sd , age , 30 + /- 4 yr ; body mass index , 25.5 + /- 4 kg/m(2 ) ) participated in the study . INTERVENTION Subjects participated in a home-based stationary cycling program from 20 wk gestation to delivery . MAIN OUTCOME MEASURES Maternal insulin sensitivity , neonatal auxology , body composition , and growth-related peptides in cord blood were measured . RESULTS Offspring of  exercisers  had lower birth weight ( sd score , control , 0.23 + /- 0.8 ; exercise , -0.19 + /- 0.9 ; P = 0.03 ) and body mass index at birth ( sd score , control , 0.40 + /- 0.9 ; exercise , -0.01 + /- 0.09 ; P = 0.04 ) . The reduction in maternal insulin sensitivity in late gestation was not affected by exercise ( P = 0.45 ) and was unrelated to offspring size . Exercise offspring had lower cord serum IGF-I ( P = 0.03 ) and IGF-II ( P = 0.04 ) . CONCLUSIONS Regular exercise was associated with lower birth weights and reduced cord concentrations of growth-related peptides , suggesting an influence of exercise on endocrine regulation of fetal growth . These effects on offspring growth were not associated with an exercise training effect on maternal insulin sensitivity OBJECTIVE The purpose of this study was to test the null hypothesis that the volume of exercise at different times during pregnancy has no effect on fetoplacental growth . STUDY DESIGN Seventy-five women who exercised regularly were evaluated before pregnancy and r and omly assigned at 8 weeks ' gestation to one of 3 exercise regimens for the remainder of pregnancy . Primary outcome variables included placental growth rate , birth weight , and placental volume at term . RESULTS The offspring of the women who were r and omly assigned to a high volume of exercise in mid and late pregnancy were significantly lighter ( 3.39 kg vs 3.81 kg ) and thinner ( 8.3 % fat vs 12.1 % fat ) than those offspring born of women who were r and omly assigned to reduce their exercise volume after the 20th week . Maternal weight gain , fresh placental volumes , and histomorphometric indices of placental function were greater in the high-low group . CONCLUSION These data indicate that a high volume of moderate-intensity , weight-bearing exercise in mid and late pregnancy symmetrically reduces fetoplacental growth , whereas a reduction in exercise volume enhances fetoplacental growth with a proportionally greater increase in fat mass than in lean body mass
Background Fetal growth is dependent upon utero-placental vascular supply of oxygen and nutrients from the mother and has been proposed to be compromised by vigorous intensity exercise in the third trimester .
The aim of this systematic review was to investigate the effects of vigorous intensity exercise performed throughout pregnancy , on infant and maternal outcomes .