This study evaluated the effects of participation in aerobic exercise on pregnancy outcomes. Pregnancy outcomes included type of delivery, length of labor, gestational age, neonatal birth weight, and maternal weight gain. The 137 nulliparas were categorized as active (N=44) or sedentary (N=93) based on self-reported aerobic exercise. Findings from this study suggest that pregnant women who were active during pregnancy were more likely to have vaginal deliveries than sedentary women. No significant differences between active and sedentary women were found in neonatal birth weight, maternal weight gain, length of labor, or gestational age.