Mermaid Syndrome

Facts About The Mermaid Syndrome - A Rare Birth Defect

The mermaid syndrome is a birth defect in which a baby's legs are fused together. Fortunately this condition, also known as sirenomelia, is quite rare. Even though the condition can be treated surgically, it is usually fatal, as more than the legs are usually involved. Abnormal kidney development, or even an absence of kidneys, often accompanies this deformity. Approximately one in every 70,000 live births have this condition.


Sadly, there have been few survivors of this syndrome. Initially the battle for survival must involve surgery to deal with malformed or absent body organs. Kidneys, bladders, the stomach, and even the lungs may be involved. Major surgery on a baby only a few days old does not bode well as far as the prognosis for recovery in concerned. Surgery to deal with the malformed legs often has to wait until much later, perhaps more than a year, assuming the infant survives the initial course of treatment. Even when this is the case, the mermaid syndrome normally goes beyond fused bones. In some instances leg bones, and foot bones may be missing altogether. The truth is, there are only three known survivors of the mermaid syndrome, and although the initial treatments in these cases were considered successful, the survivors still face many years of corrective surgery, not only on their legs, but on various internal organs as well.

Parents-to-be faced with the knowledge of the fetus having this condition have the most difficult of choices to make. Should the pregnancy be terminated at the earliest possible date, or should birth be allowed, knowing almost certainly that the baby will die within a few days. This is a dilemma that no one should have to face, and fortunately only a very few do.


There is little knowledge of what the causes of mermaid syndrome are. Genetics may play a role, but this has yet to be proven. The defects do seem to be more prevalent in cases where the parents do not practice good hygiene, or one or both are in generally poor health, but statistics here can be misleading, and do not point to any specific cause. The relative rarity of the condition, coupled with the slim chances of survival for more than a few days, makes study of the condition very difficult indeed.

Of the three known survivors, the oldest is now over 20 years old (born in 1988) and has successfully had her legs surgically separated. A second child, born in 1999, was born with a missing bladder, colon, uterus and vagina, a missing kidney, and a partial kidney. The girl has successfully gone through a pair of kidney transplants, but has to date not undergone surgery for separation of her lower limbs.

The third survivor also had serious kidney defects, one deformed and the other practically non-existent. This girl, born in 2004 underwent successful surgery to partially separate her legs in 2005 but suffered complications from the surgery in the process. She was able to undergo a second operation a year later however, and took her first steps in late 2006. Although her prognosis is reasonably bright, she still faces years of rehabilitation and further corrective surgery.

There have been a number of detailed cases recorded involving babies who did not live beyond the expected day or two. In almost all cases, the upper organs, including the heart and lungs, and the upper limbs, were perfectly formed and without abnormality. Most of the malformations occurred from the waist down, at which point, the infant could be said to have a single limb. Abnormalities in the kidneys, the bladder, the colon, and genitals were common, with the genitals often missing completely. In several of these cases, the mother had a history of drug abuse; however it has not been proven that there is any direct link.

The term sirenomelia has its roots in Greek mythology, and refers to the mermaids in the sea, also called sirens, who lured sailors to their deaths - a rather romantic tale associated with a very terrible birth defect.