Which of the following is NOT a risk factor of secondhand smoke for a developing fetus?

Secondhand smoke exposure during pregnancy presents numerous risks to fetal development, and increased oxygen-carrying capacity is not one of them.

When a pregnant woman is exposed to secondhand smoke, the harmful chemicals can lead to various adverse outcomes for the fetus. These include fetal growth restriction, intrauterine growth retardation, and decreased nutrient delivery. Each of these conditions is associated with the negative impacts of toxins and carbon monoxide found in tobacco smoke, which can hinder the oxygen supply and nutrient flow to the developing fetus, ultimately affecting its growth and overall health.

In contrast, the notion of increased oxygen-carrying capacity is misleading in this context. Tobacco smoke exposure can actually decrease the availability of oxygen to the fetus because carbon monoxide competes with oxygen for binding to hemoglobin in the mother's blood. Therefore, rather than increasing the oxygen-carrying capacity, secondhand smoke decreases it, leading to potential complications in fetal development. This understanding underlines why the correct answer identifies increased oxygen-carrying capacity as not being a risk factor for a developing fetus exposed to secondhand smoke.