This is another reason pregnant women are at a disadvantage. Mosquitoes can detect carbon dioxide using a special organ called a maxillary palp from as far as 164 feet away. Since everyone emits CO2 simply by exhaling, it comes down to relative amounts. Unfortunately for mothers-to-be, pregnancy causes women to emit 21 percent more CO2. This is also why kids are often safe from bites, when bigger, more CO2-emitting adults are around.