Yes, mosquitoes do seem to find pregnant women more enticing than women who aren't pregnant.

In addition to the annoyance of itching and scratching, greater risk for mosquito bites means greater risk for the Zika virus as well as other diseases transmitted by mosquitoes, like West Nile virus, dengue fever, and malaria.

While some people are genetically more attractive to mosquitoes, there are other factors. Certain substances on the skin's surface or in the breath can attract mosquitoes from as far away as 100 feet. The most alluring scents include lactic acid (which builds up when muscles are working and is released in sweat) and carbon dioxide (which we exhale with each breath and also release in sweat), especially when combined with heat and moisture.

Researchers at the University of Durham, England, and the Medical Research Council in Gambia, Africa, found that mosquitoes bit pregnant women twice as often as women who weren't pregnant. One explanation, the researchers suggest, is that in later pregnancy, moms-to-be breathe more heavily, exhaling 21 percent more air — including a larger-than-normal amount of carbon dioxide — than other women.

Another contributing factor may be the rise in body temperature during pregnancy. An increase in body heat means that pregnant women release more volatile substances from their skin, again making them more easily detected by mosquitoes.

"All this speculation makes sense," says Michael Smith, professor of dermatology at Vanderbilt University in Nashville, Tennessee, "but it's not proven. Bottom line: We don't know why pregnant women are more popular with mosquitoes, but they appear to be."

Find out which insect repellents are safe to use during pregnancy and see 7 ways to protect yourself from mosquitoes.