PURPOSE: The purpose of this study was to examine the effect of the yoga during pregnancy on the maternal weight, delivery experience and infant birth weight. METHOD: The nonequivalent control group pre test-post test design was used. The participants were the healthy pregnant women, whose pre-pregnancy BMI was normal, gestational period was more than 20 weeks. The final sample consisted of 21 mother-infant dyads for experimental group and 20 dyads for control group and who agreed to participate in this study. Data were collected from February 1st to December 15th, 2006. The Qi exercise prenatal program was carried out for 90 minutes a day, 2 times a week for 12 weeks. The data were analyzed using SPSS 16.0 Program. RESULT: The degree of maternal weight gain(p<.001), labor pain(p<.001), discomfort after delivery(p<.001) and infant's birth weight(p<.001) were significantly different between two groups. CONCLUSION: The yoga during pregnancy managed weight gain of mothers. Therefore, this study suggests that yoga during pregnancy to promotes stabilization can be beneficial for maintaining healthy weight, decreasing labor pain and discomfort after delivery for pregnant women and increasing infant's birth weight.