Effect of a physical exercise program during pregnancy on uteroplacental and fetal blood flow and fetal growth: a randomized controlled trial.

OBJECTIVE: To estimate the effect of supervised physical exercise on maternal physical fitness, fetoplacental blood flow, and fetal growth.

METHODS: This was a randomized controlled trial comparing three groups of pregnant women. Groups were as follows: exercise initiated at 13 weeks (group A); exercise initiated at 20 weeks (group B); and a control group (no supervised exercise; group C). The women in groups A and B walked at moderate intensity three times weekly. Physical fitness level was evaluated at weeks 13, 20, and 28. Fetal growth and uteroplacental blood flow were evaluated monthly. Birth weight was registered. Analysis of variance for repeat measures was used for outcomes evaluated throughout pregnancy. Risk ratio was used as a measure of the relative risk of preeclampsia, fetal growth restriction, macrosomia, small-for-gestational-age newborns, and large-for-gestational-age newborns.

RESULTS: All the women analyzed completed more than 85% of the program. According to the evaluation conducted at week 28, physical fitness improved, with mean maximal oxygen consumptions (VO2max) of 27.3±4.3 (group A), 28±3.3 (group B), and 25.5±3.8 (group C; P=.03). Mean birth weights were 3,279±453 g (group A), 3,285±477 g (group B), and 3,378±593 g (group C; P=.53), with no difference in the frequency of large for gestational age or small for gestational age. No association was found between the practice of physical activity and the variables investigated (preeclampsia, fetal weight, blood pressure, and pulsatility index of the uterine, umbilical, and middle cerebral arteries).

CONCLUSION: Moderate-intensity walking improved the physical fitness level of healthy, pregnant, previously sedentary women without affecting fetoplacental blood flow or fetal growth.

CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00641550.

LEVEL OF EVIDENCE: II.