THE EFFECT OF MATERNAL EXERCISE ON SOMATIC GROWTH AND LUNG DEVELOPMENT OF FETAL RATS - MORPHOLOGIC AND MORPHOMETRIC STUDIES

Our study was aimed at elucidating the effect of strenuous maternal exercise (running at a speed of 20 m/min) on fetal somatic growth and lung development. Dams were separated into three groups: (1) exercising during the entire course of pregnancy; (2) exercising from the 16th to the 20th gestational day; and (3) controls treated in the same manner as the exercising animals, but not exercised. There were no differences in the mother's body weight (mother's body weight - total body weight of the fetuses) among the three groups. Overall growth and lung development in fetuses from mothers that exercised during the entire course of pregnancy showed markedly decreased size and weight of body and lung, smaller air spaces and thicker future alveolar walls, and fewer osmiophilic lamellated bodies in alveolar type II cells. The morphometric data of fetuses from mothers that had exercised only during late gestation were similar to those of control animals. The ratio of fetal lung volume to body weight was the same in all three groups. These findings indicate that long-term strenuous maternal exercise induces retardation of fetal lung development, possibly accompanied by a disturbance of overall growth. Maternal exercise represents another means of manipulating lung development.