For many years, the US Food and Drug Administration (FDA) had a letter system for medicines used during pregnancy.

Medicines were placed into one of 5 groups: A, B, C, D, or X. The letter groups were based on known effects the medicine has on a developing baby during pregnancy. The safest groups were A and B, because studies showed these medicines were safe. Medicines in the D group might be harmful to a baby but might be needed because of how serious the illness was for the woman. Medicines in the X group were medicines that should never be used in pregnancy. Unfortunately, most medicines were in the C group, which was the letter used when there were not enough studies to know if a medicine was safe or not.

By the end of 2018, no medicines will be put in a letter group. Instead, more information about the medicine is going to be given out with the medicine. The new system includes a lot of information, and it uses the terms "safe" or "not safe" for new medicines. Medicines that are in the A, B, C, D, or X letter system will be moved to the new system over the next several years.

There are not many medicines that are harmful if taken when you are pregnant. Some of the medicines that are not safe to use include birth control pills, the acne medicine isotretinoin (Accutane), a few of the medicines called statins that are used for high cholesterol, and the antibiotics tetracycline (Teramycin) and doxycycline (Adoxa). In addition, ergotamine (Cafregot) which is used for migraine headaches and the ulcer medicine misoprostol (Cytotec) should not be used during pregnancy. Most vaccines are safe during preg-nancy.

The Centers for Disease Control and Prevention has information about vaccine safety during pregnancy:

https://www.cdc.gov/vaccines-pregnancy/?CDC_AAref_Val=https://www.cdc.gov/vaccines/pregnancy/pregnant-women/index.html

Your baby develops most rapidly in the first 12 weeks of your pregnancy. This is the time when you want to avoid exposing the baby to anything that could be harmful, such as alcohol. To be safe, check with your health care provider before taking any medicine when you are pregnant, including herbs and drugstore medicines. During early pregnancy you should take folic acid to help protect your baby from some spinal birth defects.

Tell your health care provider what medicines you are taking if you want to get pregnant or if you might be pregnant. Most medicines that you need to take regularly are safe. But some medicines can be changed to a lower dose or a different medicine to lower the risk to your baby.

Check with the pharmacist or your health care provider before you take any medicines during pregnancy, even ones you can buy without a prescription.

Even if your diet is good, a daily multivitamin is a good idea. All prenatal vitamins are pretty much the same, so buy the cheapest kind. If you find that your vitamins upset your stomach, take a children's chewable vitamin. Be sure you get at least 400 micrograms of folic acid every day in the vitamin you chose. The number of micrograms of folic acid is on the label of the bottle.