A: In the past, we advised pregnant women to wait until the second trimester of pregnancy before obtaining the flu vaccine. More recently, the Centers for Disease Control and Prevention (CDC) and the American College of Obstetricians and Gynecologists (ACOG) have issued recommendations stating that all pregnant women should have a flu shot if they're pregnant during flu season, which lasts from October to May.

The flu vaccine contains an inactive (killed) virus that doesn't pose a threat to a developing baby. Women are advised to get the vaccine as early as possible in their pregnancy in order to avoid serious health complications that could result from acquiring the flu.

Your healthcare provider may offer you the vaccine during your routine prenatal visit or you can request it at the beginning of flu season. The vaccine takes two weeks to become effective, so the earlier you obtain your shot the sooner you'll be protected. Keep in mind that the vaccine changes each year. Thus, a flu vaccine from a prior year won't protect you from the risk of flu for the current year.

Flu shots are especially important for women with chronic conditions such as asthma, heart disease or diabetes. Women who are actively sick or who have a fever should postpone the vaccine until they are well. Also, the vaccine is not recommended for women with allergies to eggs or with a history of allergies to the flu vaccine. Finally, if you've ever had a rare condition called Guillain-Barre syndrome, you'll need to discuss whether the risks of the vaccine outweigh potential benefits.