When designing a prenatal fitness program the key components of intensity, duration, frequency, and mode are used, but specific modifications in the level of progression, supervision, and monitoring are needed in order to keep the exercise safe for mother and fetus. The goal of a prenatal exercise routine is to maintain or improve overall fitness, strength, and flexibility. Keep in mind that each woman’s fitness level and ability will vary, and as pregnancy progresses changes in her body will affect her ability to exercise comfortably.