Protein-calorie malnutrition in the young pregnant rat: factors involved in fetal growth impairment.

Factors involved in fetal growth retardation as seen in pups of protein-deprived young rats are examined. Young (50 to 55-day old) and adult (90 to 100-day old) rats were fed a diet of low (6%) or normal (25%) protein content during pregnancy. Dams and neonates were killed soon after parturition. Young malnourished dams showed a significant reduction in circulating glucose levels while their pups had significantly lower birth weights and circulating glucose and insulin levels than those of young control mothers. Such alterations were not seen in adult animals. Maternal malnutrition did not affect circulating levels of thyroxine in the neonates. These data indicate that maternal hypoglycemia may play an important role in determining blood glucose and insulin reduction and, consequently, the low birth weight seen in pups of young malnourished rats.