At four weeks pregnant, you should avoid (16) (17):
Chemical exposure to cleaning products, mothballs, wall paints, fake tan products (containing dihydroxyacetone), and hair treatment products
Handling cat litter as it increases the risk of toxoplasmosis
Undercooked meat and eggs. They may increase the risk of contracting infections such as listeriosis and toxoplasmosis, which may lead to serious illnesses