Efeito do exercício físico durante a gravidez sobre o fluxo sanguíneo feto-placentário e o crescimento fetal : ensaio controlado e aleatorizado / Effect of exercise during pregnancy on the blood flow fetal-placental and fetal growth : randomized controlled trials

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

27/02/2012

RESUMO

Introduction: Fetal growth has always been one of the major concerns regarding the practice of exercise during pregnancy, with discussions on whether the redistribution of fetoplacental blood flow during physical exercise and the bypass of blood from the viscera to the muscles could lead to transitory fetal hypoxia. Objective: To study the. E effect of supervised physical exercise on fetoplacental blood flow and fetal growth. Methods: A randomized, controlled trial was conducted to compare three groups of pregnant women: walking initiated at 13 weeks of pregnancy (Group A), walking initiated at 20 weeks of pregnancy (Group B) and a control group of women who did no supervised physical exercise (Group C). Overall, 187 pregnant women were included in the study: 62 allocated to Group A, 65 to Group B and 60 to Group C. After losses, analysis was conducted on 54, 60 and 57 women in Groups A, B and C, respectively. The women in the intervention groups (A and B) walked at moderate intensity three times a week. Physical fitness level was evaluated at the 13th, 20th and 28th weeks. Fetal weight, uteroplacental blood flow and maternal blood pressure were evaluated every four weeks. Birthweight was also assessed. A sub-sample of 88 healthy women in the 36th week of pregnancy was submitted to moderate intensity walking and computerized cardiotocography (Sonicaid 8002 system) during three phases: resting, treadmill walking and recovery. Initially, bivariate analysis was conducted to test the randomization process. For the analysis of some outcomes evaluated throughout pregnancy (fetal weight, systolic and diastolic blood pressure and the pulsatility indices of the uterine, umbilical and middle cerebral arteries), the longitudinal model was used. To evaluate the association between bradycardia and the numerical variables, analysis of variance (ANOVA) was used for continuous variables and the Kruskall-Wallis test for discrete variables and those continuous variables for which distribution was not normal. Finally, the frequency of bradycardia (fetal heart rate <110 bpm) was determined and stepwise multiple logistic regression was performed to identify the principal factors associated with its occurrence. The study was approved by the internal review board of the State University of Paraíba under reference number 0323.0.133.000-07. Results: Findings are reported as two papers. The mean number of days on which exercise was performed was 68 in Group A and 46 in Group B, with all the women completing more than 85% of the physical exercise program. An improvement in physical fitness was registered at the 28th week, as shown by mean VO2max values: 27.3 ± 4.3 (Group A), 28 ± 3.3 (Group B) and 25.5 ± 3.8 (Group C), p = 0.03. No difference was found between the groups with respect to their baseline characteristics. Mean birthweight was 3,279 ± 453 grams in Group A, 3,285 ± 477 grams in Group B and 3,378 ± 593 grams in Group C (p = 0.53). There was no effect of exercise on the number of small- or large-for-gestational-age infants. No association was found between physical exercise and the other variables investigated (preeclampsia, and fetal weight, blood pressure and the pulsatility indices of the uterine, umbilical and middle cerebral arteries throughout pregnancy). Mean fetal heart rate decreased during walking (resting: 137 bpm, treadmill walking: 102 bpm and recovery: 140 bpm; p<0.001), with 78% of fetuses presenting bradycardia. Improvement in physical fitness was considered a protective effect, while an increase in maternal weight represented a risk factor for bradycardia. Conclusions: In previously sedentary, healthy pregnant women bearing a single fetus, a program of supervised physical exercise of moderate intensity up to the end of pregnancy appears to exert no significant effect on the outcomes evaluated, influencing only physical fitness level. Despite the high percentage of bradycardia found during walking, exercise provide to be safe for healthy fetuses with the ability to readapt to situations in which blood flow is reduced. This study was registered on the Clinical Trials platform under reference number NCT00641550.

ASSUNTO(S)

caminhada peso ao nascer pre-eclâmpsia walking birthweight preeclampsia

ACESSO AO ARTIGO

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