Dana, a 24-year-old patient who is 5 weeks pregnant with her first child, is visiting the office for a routine...

Dana, a 24-year-old patient who is 5 weeks pregnant with her first child, is visiting the office for a routine checkup.  She says that birth defects are common in her family, and she is concerned about the possibility that her baby will have defects as well.  What should you tell her?