With recent reports that three babies have been born in the U.S. with a birth defect linked to the Zika virus, it’s important for pregnant women (or women who are planning to become pregnant) to understand the causes, risks and how to protect themselves from the virus.

Zika contributes to the development of microcephaly, a birth defect that causes incomplete brain development and small heads in babies born to infected mothers. The virus began showing up in Brazil about one year ago, and has since been detected in at least 39 countries. Zika is a blood-borne virus that is primarily transmitted through mosquitoes, but can also be spread through unprotected sex and blood transfusions.

According to this recent article, the Centers for Disease Control and Prevention (CDC) says there are more than 300 pregnant women in the U.S. with evidence of possible virus infection.

How to Protect Yourself from the Zika Virus

Since a vaccine for Zika doesn’t currently exist, the most effective way to avoid the disease is to avoid getting bitten by mosquitoes. The CDC recommends insect repellent products that contain DEET, oil of lemon eucalyptus, picaridin, or IR 3535.

It’s important to apply insect repellent after you apply sunscreen and over your clothing. It has been reported that the type of mosquito that carries Zika has a tendency to bite feet and ankles, so be sure to cover those areas well.

When outside, wear long pants (avoid yoga pants as they are easy to bite through) and long sleeves if possible, and keep your feet covered with shoes and socks.

Eliminate all standing water inside and around your home to prevent mosquitoes from breeding. Swimming pools are safe because they contain chlorine, which keeps mosquitoes away.

If you’re pregnant, avoid traveling to affected areas like Brazil. The CDC maintains a list of countries and territories that are Zika-active (view it here).