Which of the following is a relative contraindication to exercise during pregnancy?

Severe anemia is considered a relative contraindication to exercise during pregnancy because it can lead to additional complications for both the mother and the fetus. When a pregnant individual has severe anemia, their blood's capacity to carry oxygen is diminished. This can result in inadequate oxygen supply to both maternal and fetal tissues, particularly during physical activity where oxygen demand increases. Consequently, while some exercise may be beneficial and appropriate for individuals with mild anemia, those with severe anemia should be cautious, as strenuous activities could exacerbate their condition and lead to symptoms such as fatigue, dizziness, or even fainting.

In this context, other options like preeclampsia and underweight status are more absolute contraindications or require evaluation and management beyond just moderating exercise. Frequent headaches can also arise from various causes, but they do not universally prohibit exercise unless accompanied by other concerning symptoms or associated conditions. In summary, recognizing severe anemia as a relative contraindication underscores the importance of ensuring maternal health is optimized before engaging in exercise during pregnancy.