A: Vaccinations containing active virus are contraindicated within three months of conception. Although the live virus in these vaccines have been weakened, they could be harmful to a developing baby and should not be administered during pregnancy. Vaccines that use toxoids - substances derived from inactivated virus - are safe to use during pregnancy. Here are some vaccines that may be advised during your pregnancy:

(1) Influenza vaccine. This is the most common vaccination recommended during pregnancy. The flu can be particularly debilitating during pregnancy, and women in the second and third trimester are advised to receive this vaccine if flu season is approaching. This is usually from October to December. The vaccine protects against the three most likely viruses to cause the flu in the coming season. One study showed the risk of influenza decreased 19-fold when pregnant women were immunized. Being vaccinated in a previous year doesn’t protect you the subsequent year, remember. You must be immunized each year for current protection.

(2) Tetanus. You should receive immunization every 10 years, including during pregnancy. Tetanus is a disease of the nervous system causing muscle spasms, including “lockjaw,” severe convulsions and death. It comes from a bacterium found in soil and animal waste and may result from sustaining a deep or dirty wound. Checking previous medical or school records will help you known if you are due for another tetatus vaccine.

(3) Hepatitis B. This is a genetically engineered vaccine to protect against a viral infection that causes liver damage. If you are a health-care worker, work with small children in a daycare center or live with someone infected with Hepatitis B you should consider having this vaccine. During pregnancy, a mother can pass Hepatitis B to her baby during labor and delivery.

(4) Additionally, you may require specific vaccines or boosters if you live in an area where Hepatitis A is common, or if you plan to travel to a developing country during your pregnancy. Inform your health care provider of any travel plans well in advance of your departure.