Trisomy 18 is also called Edwards syndrome (or Edward's syndrome), and is the second most common trisomy, after Trisomy 21 (Down syndrome). It occurs in about 1:5000 to 1:8000 births.
Trisomy 18 syndrome is due to the presence of an extra #18 chromosome, meaning that BABY MOONEY has three chromosomes in the eighteenth position instead of the normal two.
Unlike Down syndrome, Edwards Syndrome is usually fatal, with most of the babies dying before birth and those who do make it to birth typically living only a few days. However, a small number of babies (<10%) live at least one year.
Websites with more info:
Trisomy 18 Foundation
**All this info was taken from other sites and we are praying for anything but "typical".