Q: I can't decide whether I should get a flu shot. I'm two months pregnant. What are your thoughts?

A: It's a good idea for everyone 6 months of age and older to get a vaccination against influenza. This is especially true for pregnant women and those who expect to become pregnant. Pregnancy puts women at a higher risk of getting serious health problems if they get seasonal flu.

Still, I understand your uncertainty. For most pregnant women, protecting the health of their unborn baby is their No. 1 concern. So many won't take a medicine or have a medical procedure unless they know it's absolutely safe for the baby.

Here's why I recommend the flu shot:

The flu shot can protect infants who can't get a vaccination. The mother can pass protective antibodies to her unborn child. These may help protect the baby after birth.

If you do get the flu, you have a higher than average risk of getting pneumonia. Pneumonia lowers your blood oxygen level. This means your unborn baby may not get the oxygen needed for normal development.

Having the flu in pregnancy raises your risk of a miscarriage or giving birth too early.

Flu usually causes a fever, sometimes a very high fever. Women who have a fever during early pregnancy are more likely to deliver a baby with a neural tube defect, such as spina bifida.

Some people worry about the preservative used in many vaccines. The preservative is called thimerosal. The safety of thimerosal has been extensively studied. There is no scientific evidence of any harmful effects on babies when mothers get shots that have this preservative.

(Howard LeWine, M.D., is a practicing internist at Brigham and Women's Hospital, Boston. Mass., and Chief Medical Editor of Internet Publishing at Harvard Health Publications, Harvard Medical School.)

(For additional consumer health information, please visit http://www.health.harvard.edu.)