The study will be conducted at Institute of Medicine Professor Fernando Figueira (IMIP), Brazil. The patients will be included in the study by consent after an explanation of the study goals. Women will be considered eligible for enrollment if they fulfill all the inclusion criteria and none of the exclusion criteria. Sample size was calculated with the aim of reducing glucose levels by 20% in intervention GDM group. A power of 80% and a level of significance of 5% was accepted and the calculated sample size in each arm was 30 patients. Assuming a drop out of 20%, 72 pregnant women will be included in the study. 36 gestational diabetics and and 36 normoglycemic pregnant women will develop an aquatic physical exercise in a thermal pool, 45 minutes per one time, from rehabilitation center of the IMIP. Before to practice the aquatic exercise women will have their physical capacity assessed by the Six minutes walk test and fetal conditions will be assessed by ultrasound. They will also be submitted to a dermatological examination by specialist. Primary endpoint will be glucose levels (glycemic test), secondary endpoints will be the following maternal and fetal: blood pressure, heart rate, respiratory rate, oxygen saturation level, fetal cardio beat and fetal movement.The variables will be measured before and after the water exercise session. Maternal and fetal characteristics of the study sample will be presented by group, intervention and control in terms of mean and standard deviation. For group comparisons of glucose levels and maternal and fetal variables, continuous and nominal data will be analyzed by t test for unpaired data and χ2 tests, respectively. Data will be analyzed using the intention-to-treat principle. Statistical analysis will be performed with the STATA version 12.0 and the level of significance will set to <0.05. Even in cases where there is the appearance of some criterion for discontinuation during the intervention (Aquatic physical exercise), the patient will be considered part of the group which was initially included in the randomization (intent to treat) and is not excluded from the study. The physical proprieties of water provide aquatic exercises as ideal for pregnant women. An aquatic physical exercise program developed with pregnant women in a thermal pool and under a physiotherapist supervision must ensure compliance. It is expected that this study provide evidences to the real role of aquatic physical exercise on glycemic control of GDM.