Your Baby's Development

This first week is actually your menstrual period. Because your expected delivery date (EDD) is calculated from the first day of your last period, this week counts as part of your 40-week pregnancy even though your baby hasn't been conceived yet.

Your Body

During pregnancy, your healthy habits and your baby's health go hand in hand. But even before you become pregnant, it's important to prepare your body:

• Avoid alcohol, drugs, and tobacco products. These substances can cause birth defects, fetal alcohol syndrome, respiratory problems, low birth weight, and other health problems.
• Talk to your doctor about any prescription and nonprescription (OTC) drugs you are taking. You'll need to take special precautions with medicines because many prescription and over-the-counter medications can harm the fetus. But don't stop taking prescription drugs without talking to your health care provider, who will help you weigh the potential benefits and risks of stopping any medicines.
• Eat a diet with needed vitamins, especially folic acid. Women who want to become pregnant should take 400 micrograms of folic acid a day. This lowers the risk of neural tube defects (problems caused by incomplete development of the brain or spinal cord), such as spina bifida. Be sure to talk to your health care provider about taking a folic acid supplement while you are trying to conceive.