Rheumatoid arthritis is a relatively common problem in women of reproductive age. Pregnancy may affect all aspects of the pharmacokinetics of the drugs used in its treatment. The effects of pregnancy on the pharmacokinetics of drugs are, for the most part, not clinically significant. The pharmacokinetics of placental transfer and fetal safety have been specified for many drugs. Drugs used in rheumatoid arthritis can be classified into 3 classes: those with the greatest safety for the fetus, those that are unsafe for the fetus, and those for which there are insufficient data to determine the risk to the fetus.