Sirenomelia, alternatively known as Mermai Syndrome is a very rare congenital deformity in which the legs are fused together, giving the appearance of a mermaid. This condition is found in approximately one out of every 70,000 live births (about as rare as conjoined twins) and is usually fatal within a day or two of birth because of complications associated with abnormal kidney and bladder development and function. It results from a failure of normal vascular supply from the lower aorta in utero. Maternal diabetes is associated with caudal regression syndrome and sirenomelia , although this association is not generally accepted.