Chemicals and viruses that can reach the developing baby and cause harm

a.)cross-sectional

b.)longitudinal

c.)teratogens

A teratogen is something that can cause or raise the risk for a birth defect in a baby.

Explanation:

exposure to hazardous carcinogens and toxic substances can cause breathing problems, such as copd and various types of cancer. it also increases the risk of heart attacks and strokes and has serious (but no less unattractive) side effects, such as aging, yellow teeth, a terrible smell and damage to the vocal cords.