Which is NOT a way that a fetus is harmed when a pregnant woman smokes?

The answer is correct because cigarette smoke does not aid in the proper development of a fetus. In fact, smoking during pregnancy poses significant risks to fetal health, leading to numerous adverse outcomes.

When a pregnant woman smokes, harmful substances such as nicotine and carbon monoxide enter her bloodstream, which in turn affects the fetus. These toxins can inhibit proper growth and development, leading to low birth weight, premature birth, and developmental issues.

Other options detail the negative impacts of smoking: environmental tobacco smoke (ETS) clogs the lungs, limits oxygen flow to the fetus, and allows toxins to enter the fetal bloodstream, all of which contribute to detrimental health effects. Thus, only the notion that cigarette smoke assists in fetal development is incorrect, underscoring the dangers associated with smoking during pregnancy.