At the end of the 1st trimester/very beginning of the second, parents are given the option to have a NT scan done on their babies. At this visit, blood is taken and a thorough U/S is done that helps determine if your baby will have any major defects (more info: http://www.babycenter.com/0_nuchal-translucency-screening_118.bc). The problem with the test is that it has MANY false positive reads which leaves the parent with 2 choices: take a chance or go into further testing with an amnio. With an amnio they stick a long but very thin needle into the uterus to extract amniotic fluid (more info: http://www.babycenter.com/0_amniocentesis_327.bc) that gives more information. The problem here is that there is risk of miscarriage with the test as well as the CVS alternative (http://www.babycenter.com/0_chorionic-villus-sampling-cvs_328.bc).
With these results parents are able to get "more prepared" for a special needs baby or terminate the pregnancy in case they feel unprepared to raise a special needs baby.
We decided not to test. This was a personal decision that we may not have made if we didn't already have a loss on our hands. While the NT is harmless, there is no way we would have been comfortable moving on to more complex tests. We didn't want to worry for 6 months with a possible false positive over our heads and know for certain we wouldn't terminate this or any pregnancy.
Modern medicine has come so far, if only it would come a bit further!