 Sample size was calculated with the aim of reducing glucose levels by 20 in intervention 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 will develop an aquatic physical exercise program in a thermal pool, three times per week during two months, and 36 gestational diabetics will receive usual care from IMIP. 