Answer: Pregnancy

Despite the long standing notion that women are bitten by mosquitoes more than men, that simply doesn’t hold up (outside of the situation we’re about to discuss). Mosquitoes are primarily attracted to heat and carbon dioxide, and as men are typically larger than women physically and generate more heat and carbon dioxide, mosquitoes like them a bit more.

The exception to this pattern is pregnancy. The increased mass, heat, and carbon dioxide output brought on by pregnancy creates a juicier target, if you will, for mosquitoes and increases the likelihood of their being bitten. By the later stages of pregnancy when a woman’s body is metabolizing for both herself and a nearly grown fetus, the amount of exhaled carbon dioxide is approximately 21 percent higher than that of a non-pregnant woman.