***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: 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 Background To evaluate the association between water aerobics , maternal cardiovascular capacity during pregnancy , labor and neonatal outcomes . Methods A r and omized , controlled clinical trial was carried out in which 34 pregnant women were allocated to a water aerobics group and 37 to a control group .  All women were su bmi tted to submaximal ergometric tests on a treadmill at 19 , 25 and 35 weeks of pregnancy and were followed up until delivery . Oxygen consumption ( VO2 max ) , cardiac output ( CO ) , physical fitness , skin temperature , data on labor and delivery , and neonate outcomes were evaluated . Frequency distributions of the baseline variables of both groups were initially performed and then analysis of the outcomes was carried out . Categorical data were compared using the chi-square test , and numerical using Student 's t or Mann-Whitney tests . Wilk 's Lambda or Friedman 's analysis of repeat measurements were applied for comparison of physical capacity , cardiovascular outcomes and maternal temperature . Results VO2 max and physical fitness were higher in both groups in the second trimester , returning to basal levels in the third trimester . In both groups , CO increased as pregnancy progressed and peak exercise temperature was higher than resting temperature , increasing further after five minutes of recovery and remaining at this level until 15 minutes after exercise completion . There was no difference between the two groups regarding duration ( 457.9 ± SD 249.6 vs 428.9 ± SD 203.2 minutes ) or type of delivery . Labor analgesia was requested by significantly fewer women in the water aerobics group ( 27 % vs 65 % ; RR = 0.42 95%CI 0.23–0.77 ) . Neonatal results were similar in both groups . Conclusion The regular practice of moderate water aerobics by sedentary and low risk pregnant women was not detrimental to the health of the mother or the child . There was no influence on maternal cardiovascular capacity , duration of labor or type of delivery ; however , there were fewer requests for analgesia during labor in the water aerobics group Objective The influence of an exercise programme performed by healthy pregnant women on maternal glucose tolerance was studied . Study design A physical activity ( PA , l and /aquatic activities ) programme during the entire pregnancy ( three sessions per week ) was conducted by a qualified instructor . 83 healthy pregnant women were r and omly assigned to either an exercise group ( EG , n=40 ) or a control ( CG , n=43 ) group . 50 g maternal glucose screen ( MGS ) , maternal weight gain and several pregnancy outcomes were recorded . Results Significant differences were found between study groups on the 50 g MGS . Values corresponding to the EG ( 103.8±20.4 mg/dl ) were better than those of the CG ( 126.9±29.5 mg/dl ) , p=0.000 . In addition , no differences in maternal weight gain and no cases of gestational diabetes in EG versus 3 in CG ( 7 % ) ( p>0.05 ) were found . Conclusion A moderate PA programme performed during pregnancy improves levels of maternal glucose tolerance OBJECTIVE We have studied the effect of moderate physical activity that is performed by healthy women during their entire pregnancy on their perception of health status . STUDY DESIGN Eighty sedentary women were assigned r and omly to either an exercise group ( n = 40 ) or a control group ( n = 40 ) . Maternal perception of health status and several pregnancy outcomes were recorded . RESULTS Significant differences ( P = .03 ) were found between study groups in the percentage of women who perceived their health status as " very good " ; the values that corresponded to the exercise group ( n = 18 ; 54.5 % ) were better than those of the control group ( n = 9 ; 27.3 % ) . In addition , the women of the exercise group gained less weight ( 11,885 ± 3146 g ) than those of the control group ( 13,903 ± 2113 ; P = .03 ) . CONCLUSION A moderate physical activity program that is performed over the first , second , and third trimester of pregnancy improves the maternal perception of health status Background Birth weight plays an important role in infant mortality and morbidity , childhood development , and adult health . To date there are contradictory results regarding the role of physical activity on birth weight . In addition , it is question ed whether exercise during second and third trimesters of pregnancy might affect gestational age and increase the risk of preterm delivery . Hence , the purpose of this study was to examine the effect of a supervised exercise-program on birth weight , gestational age at delivery and Apgar-score . Methods Sedentary , nulliparous pregnant women ( N = 105 ) , mean age 30.7 ± 4.0 years , pre-pregnancy BMI 23.8 ± 4.3 were r and omized to either an exercise group ( EG , n = 52 ) or a control group ( CG , n = 53 ) . The exercise program consisted of supervised aerobic dance and strength training for 60 minutes , twice per week for a minimum of 12 weeks , with an additional 30 minutes of self-imposed physical activity on the non-supervised week-days . Results There was no statistically significant difference between groups in mean birth weight , low birth weight ( < 2500 g ) or macrosomia ( ≥ 4000 g ) . Per protocol analyses showed higher Apgar score ( 1 min ) in the EG compared with the CG ( p = 0.02 ) . No difference was seen in length of gestation  . Conclusion Aerobic-dance exercise was not associated with reduction in birth weight , preterm birth rate or neonatal well-being . Trial Registration Clinical Trials.gov : OBJECTIVE We examined the effect of light-intensity resistance exercise training that is performed during the second and third trimester of pregnancy by previously sedentary and healthy women on the type of delivery and on the dilation , expulsion , and childbirth time . STUDY DESIGN We r and omly assigned 160 sedentary women to either a training ( n=80 ) or a control ( n=80 ) group . We recorded several maternal and newborn characteristics , the type of delivery ( normal , instrumental , or cesarean ) , and dilation , expulsion , and childbirth time . RESULTS The percentage of women who had normal , instrumental , or cesarean delivery was similar in the training ( 70.8 % , 13.9 % , and 15.3 % , respectively ) and control ( 71.4 % , 12.9 % , and 15.7 % , respectively ) groups . The mean dilation , expulsion , and childbirth time did not differ between groups . CONCLUSION Light-intensity resistance training that is performed over the second and third trimester of pregnancy does not affect the type of delivery OBJECTIVE To study the effect on  maternal weight gain of a supervised light- to moderate-intensity exercise-based intervention performed from the ninth week of pregnancy . PARTICIPANTS AND METHODS A total of 962 healthy pregnant women were r and omly assigned to a st and ard care or exercise intervention group conducted between September 1 , 2007 , and January 31 , 2011 . The intervention included light- to moderate-intensity aerobic and resistance exercises performed 3 days a week ( 50 - 55 minutes per session ) . Excessive gestational weight gain was calculated on the basis of the 2009 Institute of Medicine ( IOM ) recommendations . Gestational body weight gain was calculated on the basis of the weight measured at the first prenatal visit ( fifth to sixth weeks of gestation ) and weight measured at the last visit to the clinic before delivery . Women were categorized into normal weight or overweight or obese . RESULTS Women in the intervention group gained less weight ( adjusted mean difference , 1.039 kg ; 95 % CI , 0.534 - 1.545 kg ; P<.001 ) and were less likely to gain weight above the IOM recommendations ( odds ratio , 0.625 ; 95 % CI , 0.461 - 0.847 ) compared with those in the st and ard care group . The main treatment effects according to body mass index category were that normal weight women in the intervention group gained less weight ( adjusted mean difference , 1.393 kg ; 95 % CI , 0.813 - 1.972 kg ; P<.001 ) and were less likely to gain weight above the IOM recommendations ( odds ratio , 0.508 ; 95 % CI , 0.334 - 0.774 ) than normal weight women who received st and ard care . No significant treatment effect was observed in overweight or obese women . CONCLUSION Supervised exercise of light to moderate intensity can be used to prevent excessive gestational weight gain , especially in normal weight women . TRIAL REGISTRATION clinical trials.gov Identifier : NCT01790347 Objective To examine the effect of regular moderate-intensity exercise ( three training sessions/week ) on the incidence of  gestational diabetes mellitus ( GDM  , primary outcome ) . We also examined if the exercise intervention modifies the association between GDM and birth weight and risk of macrosomia , gestational age , risk of caesarean delivery and maternal weight gain ( secondary outcomes ) . Methods We r and omly assigned 510 healthy gravida to either an exercise intervention or a usual care ( control ) group ( n=255 each ) . The exercise programme focused on moderate-intensity resistance and aerobic exercises ( three times/week , 50–55 min/session ) . GDM diabetes was diagnosed according to the WHO criteria and the International Association for Diabetes in Pregnancy Study Group ( IADPSG ) . Results The intervention did not reduce the risk of developing GDM ( OR 0.84 , 95 % CI 0.50 to 1.40 ) when using the WHO criteria . We observed that the intervention reduced by 58 % the GDM-related risk ( WHO criteria ) of having a newborn with macrosomia ( OR 1.76 , 95 % CI 0.04 to 78.90 vs 4.22 , 95 % CI 1.35 to 13.19 ) in exercise and control groups , respectively ) , and by 34 % the GDM-related risk of having acute and elective caesarean delivery ( OR 1.30 , 95 % CI 0.44 to 3.84 vs 1.99 , 95 % CI 0.98 to 4.06 in exercise and control groups , respectively ) . Gestational age was similar across the treatment groups ( control , exercise ) and GDM category ( GDM or non-GDM ) , and maternal weight gain was ∼12 % lower in the exercise group independent of whether women developed GDM . The results were similar when the IADPSG criteria were used instead . Conclusions Regular moderate-intensity exercise performed over the second-third trimesters of pregnancy can be used to attenuate important GDM-related adverse outcomes 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 
    Output:
    
Conclusion : Structured physical exercise programs during pregnancy appear to be safe for the neonate , mainly favoring a lower birth weight within normal range .