Final answer:
Alcohol, smoking, and illegal drugs should be totally eliminated during pregnancy as they can pose significant risks to the developing embryo or fetus. Pregnant women should also maintain a healthy diet.
Step-by-step explanation:
The substances or practices that should be totally eliminated during pregnancy are alcohol, smoking, and illegal drugs. These substances can pose significant risks to the developing embryo or fetus and can cause a range of birth defects and developmental issues.
Alcohol, when consumed during pregnancy, can cross the placenta and enter the unborn child's bloodstream, causing abnormalities in growth and development. Smoking exposes the fetus to harmful chemicals, reducing oxygen supply and increasing the risk of premature birth and low birth weight. Illegal drugs can have severe consequences for the developing fetus, leading to physical and cognitive impairments.
It is important for pregnant women to maintain a healthy diet that provides adequate nutrients for normal fetal growth and development.