Prenatal screening is done on a mom during pregnancy to determine if the baby might have a genetic condition, such as Down Syndrome, before the baby is born.

Developmental screening includes non-medical tests that determine if a child is developing physically, cognitively, socially and emotionally on schedule for their biological age. If a child is delayed in their development, this is sometimes referred to as a developmental delay. The reason a diagnosis of developmental delay is important in the world of genetics, is that a large number of genetic disorders can show up in a young child in the form of delays, missed milestones and inability for the child to sit, crawl, stand, walk, or talk at the same time as other children their age.

The words screening and testing are often used interchangeably, but they mean very different things. An out-of-range result from a screening should always be followed up by a test to confirm those results. For instance, if a child has an out-of-range newborn screen for a condition, there will always be follow-up testing to confirm or deny that screening result. The testing may confirm or deny a diagnosis.