This sheet is about rheumatoid arthritis in pregnancy and while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare providers. What is rheumatoid arthritis? Rheumatoid arthritis (RA) is a type of arthritis that mainly affects joints but can also affect other parts of the body. It is an autoimmune condition, meaning the immune system does not work the way it should, causing inflammation …