Differential effect of pre- and postnatal litter size reduction on body weight and development of stress response in the rat.

The postnatal development of pups belonging to the small, prenatally reduced litters (PRN) was compared to that of pups of the postnatally reduced litters (PST) and to that of pups of intact, normal-size litters (CON). Body adrenal and pituitary weight gain as well as maturation of the pituitary-adrenal system were enhanced in the PRN and PST pups as compared to the CON pups in the 3 postnatal weeks. However, significant differences in some data between the PRN and PST pups were found, indicating the more pronounced beneficial effect of the prenatal reduction of litter size. The postnatal litter size reduction abolished the weight gain of the testes. The prenatal reduction of litter size resulted in a similar, although less pronounced negative effect.