When it comes to mosquitoes, some people feel like they've got targets on their backs... and everywhere else, for that matter. Mosquitoes aren't fair and unbiased about their victims either. They play favorites and they don't care who knows it.
The female mosquitoes are actually the guilty parties causing all the grief. They are the ones who suck our blood, to better be able to make fertile eggs.
"Scientists do know that genetics account for a whopping 85% of our susceptibility to mosquito bites. They've also identified certain elements of our body chemistry that, when found in excess on the skin's surface, make mosquitoes swarm closer."
Mosquitoes like people with high levels of steroids or cholesterol on their skin, and poeple who produce high levels of various acids. They like people who give off more carbon dioxide. Pregnant women fall into this category.
You can pick one of many commercial mosquito repellents, or you can go for chemical-free mosquito repellents. Some of these contain citronella, cedar, geranium, lemon grass, peppermint and soybean oil. Oil of eucalyptus products, and oil of lemon eucalyptus do a very effective job of repelling mosquitoes.
http://www.webmd.com/allergies/features/are-you-mosquito-magnet