This study was designed to determine whether the exercise program during pregnancy would be associated with motor, cognitive and social skills in infants at 1 and 3 months of age, based on standard developmental assessment tools. This study was a randomized controlled trial in which 40 healthy pregnant women were allocated 1:1 to an experimental or a control group. Eligible pregnant women in the experimental group performed 50 minutes structured exercise program, three times per week; those in control group just maintained usual activity and received standard clinical care. Baseline data of mothers were collected at enrolment and their infants were evaluated for gross and fine motor skills, developmental motor quotient, cognitive and social skills at ages of 1 and 3 months by Peabody Development Motor scale, and Ages and Stages Questionnaire. Thirty- six women completed the study. After birth, the significant differences were found for gross motor (p=.026) and personal-social skills (p=.001).Although there was no significant difference between the two groups in terms of fine motor skill (p=.214), developmental motor quotient (p=.149), problem solving skill (p=.207) and communication skill (p=.487), the skills in the infants of the experimental group increased compared to the control group. This trial suggests that exercise during pregnancy may provide an opportunity to develop the offspring’s skills. Furthermore, maternal exercise also has long-lasting effects in the next months.