Phenylalanine deficiency in the food of rat. Part II. Decrease in fertility by phenylalanine deficiency in pregnancy.

Female rats fed on a phenylalanine-low diet (PheLD) before mating and 21 days afterwards did not become pregnant. Feeding with PheLD after mating, for shorter periods, diminished fertility and caused malformations in fetuses. Continuation of PheLD in feeding mothers for 3 weeks post partum caused the death of all newborns, while if mothers fed with PheLD during pregnancy were switched to standard diet post partum, their offspring did not show signs of phenylalanine deprivation.