During a baby's development in the mother's body, problems sometimes occur that can result in development of birth defects.  Most defects happen during the first 3 months of a pregnancy. Birth defects can affect how the baby's body looks or how it works, or both.  Sometimes these defects can be seen immediately and sometimes doctors need to use special tests to identify them.  The causes can include: genetics, exposures to medicines and chemicals, infections during pregnancy, and the mother not getting enough of certain nutrients while the baby is developing. Practicing healthy habits can help reduce the risks for some birth defects.  To learn more about various kinds of birth defects, read on: