Two studies that found higher-birth-weight infants in women who exercise examined women who started a new exercise program and were not fit prior to pregnancy. The discrepancies in the findings of the effect of exercise on birth weight could be attributed to the broad and unique definition of exercise used in each of the individual studies, controls used and maternal characteristics. As reviewed above, pre-pregnancy maternal fitness, trimester in which the exercise is performed and intensity of exercise appear to influence fetal weight. Many other factors, including type of exercise duration of exercise, maternal eating habits and other maternal behaviors, could also have an impact on fetal weight. Although there are conflicting results regarding the effects of exercise on birth weight, there is consistent evidence that exercise during pregnancy is not associated with an increase risk of intrauterine growth restriction. Although there are very limited data, studies suggest that at 1 and 5 years of age, children born to women who exercised during pregnancy do not suffer any adverse neurodevelopmental outcomes or problems with growth. Long-term follow-up of children of women who exercised during pregnancy warrants further investigation.