Trisomy 16 is a chromosomal abnormality in which there are 3 copies of chromosome 16 rather than two.[1] It is the most common trisomy leading to miscarriage and the second most common chromosomal cause of it, closely following X-chromosome monosomy.[2] About 6% of miscarriages have trisomy 16.[3] Those mostly occur between 8 to 15 weeks after the last menstrual period.[3]