It is possible to increase skeletal muscle fibre number in utero

The administration of porcine somatotropin (pST) to pregnant sows during early gestation (day 10 to 24) induced the formation of significantly more muscle fibres in thesemitendinosus muscle of the fetuses, representing a higher growth capacity of skeletal muscle. The pST-treatment during late pregnancy (day 80 to 94) accelerated the development of the fetus resulting in higher body weights and advanced stage of maturity at birth.