Effect of a Physical Exercise Program During Pregnancy on Uteroplacental and Fetal Blood Flow and Fetal Growth A Randomized Controlled Trial Adriana S. de Oliveria Melo, MD, PhD, João Luiz P. Silva, MD, PhD, Jousilene S. Tavares, MSc, Vivianne O. Barros, MSc, MD, Debora F. B. Leite, MD, and Melania M. R. Amorim, MD, PhD 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 com- paring 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 new- borns, and large-for-gestational-age newborns. RESULTS: All the women analyzed completed more than 85% of the program. According to the evaluation con- ducted at week 28, physical fitness improved, with mean maximal oxygen consumptions (VO 2max ) 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 associa- tion was found between the practice of physical activity and the variables investigated (preeclampsia, fetal weight, blood pressure, and pulsatility index of the uter- ine, 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. (Obstet Gynecol 2012;120:302–10) DOI: 10.1097/AOG.0b013e31825de592 LEVEL OF EVIDENCE: II O ne of the major concerns in relation to the practice of exercise during pregnancy always has been the possibility of a negative effect on fetal growth. Part of the debate has focused on whether the redistribution of fetoplacental blood flow during physical exercise, in which blood flow is rerouted from the viscera to the muscles, may result in transi- tory fetal hypoxia with compensatory fetal tachycar- dia, leading to fetal growth restriction if the effect were to persist. 1 This concern arose from experimen- tal animal studies that showed a redistribution of cardiac output, with an increase in blood flow to the muscles and skin and a decrease to the viscera. This response may represent a reduction of approximately 35% in uteroplacental blood flow, which is conse- quently redistributed as a protective mechanism, fa- voring the placenta instead of the myometrium and From the Department of Obstetrics, School Medical Sciences, University of Campinas, Campinas, the Instituto de Medicina Integral Professor Fernando Figueira (IMIP), Recife, Pernambuco, and the Instituto de Pesquisa Prof. Joaquim Amorim Neto (IPESQ), Campina Grande, Paraíba, Brazil. Supported by the Brazilian National Council for Scientific and Technological Development (CNPq) and by the Paraíba Research Foundation (FAPESQ). The authors thank the teams at the health care units of the city of Campina Grande for referring pregnant women and the collaborators at IPESQ for supporting pregnant women during the exercise program. Corresponding author: Adriana S. de Oliveria Melo, Instituto de Pesquisa Prof. Joaquim Amorim Neto, Rua Duque de Caxias 330, Prata 58100-000 Campina Grande, Paraíba, Brazil; e-mail: asomelo@gmail.com. Financial Disclosure The authors did not report any potential conflicts of interest. © 2012 by The American College of Obstetricians and Gynecologists. Published by Lippincott Williams & Wilkins. ISSN: 0029-7844/12 302 VOL. 120, NO. 2, PART 1, AUGUST 2012 OBSTETRICS & GYNECOLOGY