Congenital Abnormalities/prevention & control; Ferrous Compounds/administration & dosage; Iron Deficiencies; Magnesium Deficiency/physiopathology; Magnesium/administration & dosage; Pregnancy Complications/physiopathology; Administration, Oral; Anemia, Hypochromic/prevention & control; Animals; Aspartic Acid/administration & dosage; Aspartic Acid/toxicity; Biological Availability; Birth Weight/drug effects; Congenital Abnormalities/etiology; Diet; Dose-Response Relationship, Drug; Female; Fertility; Fetal Growth Retardation/etiology; Fetal Growth Retardation/prevention & control; Iron/toxicity; Lactation; Litter Size/drug effects; Magnesium/toxicity; Magnesium Deficiency/prevention & control; Male; Pregnancy; Pregnancy Complications/prevention & control; Pregnancy Outcome; Rats; Rats, Sprague-Dawley; Tissue Distribution; Water