Teratogenic Groups

Metabolism and malnutrtion

Metabolic teratogens are substances or conditions that disrupt normal fetal development by altering the metabolic environment of the embryo or fetus. These disruptions often result from maternal metabolic disorders or exposures to certain drugs or chemicals that interfere with the mother's metabolic processes. When this interference occurs during pregnancy, especially in the first trimester, when organ systems are forming, it can lead to birth defects or developmental abnormalities.

Metabolic conditions like diabetes and thyroid disorders are teratogenic disorders that can harm foetal development. Malnutrition deprives the foetus of essential nutrients, while diabetes can cause foetal malformations due to abnormal blood sugar levels. Hypoglycaemia affects foetal heart proteins, and excessive blood sugar can lead to neural tube defects and free radical damage. According to a Canadian review (1990–2005), infants of diabetic mothers have a 4–10% risk of major malformations, two to three times higher than in the general population.

Thyroid disorders disrupt hormone production, causing risks like miscarriage, placental abruption, preterm labour, and lower IQ in

children. in the 1940s, experiments by Josef Warkany showed that tnyroid dysfunction in pregnant rats led to malformations in off spring.

Unlike direct-acting teratogens (like some infections or radiation), metabolic teratogens typically:

Alter the mother's metabolism
Disrupt nutrient delivery or waste removal
Cause toxic accumulation of metabolic byproducts
Affect critical processes like DNA synthesis, cell division, or protein formation

Drug-Induced Metabolic Teratogens

Certain medications alter maternal or fetal metabolism in ways that lead to teratogenic effects:

Valproic acid (sodium valproate): Alters folate metabolism; associated with neural tube defects, autism spectrum disorders, and facial dysmorphisms.
Methotrexate: Interferes with folate metabolism; causes multiple congenital abnormalities.
Warfarin: Disrupts vitamin K-dependent metabolic pathways; causes skeletal and CNS malformations.