Causes & Occurance

 How Common Is It ?

Spina bifida is one of the most common malformations with which a baby can be born and is as common in boys as in girls.

In Western Australia, up until 1996 around 2 children in every 1000 were born with a neural tube defect. Since 1996, the figure has dropped to 1.3 children per 1000 births as a result of the folic acid compaign (see research). Since spina bifida accounts for approximately half of all neural tube defects, this means the birth rate since 1996 has been between 0.5 and 0.7 1000 births.

 How Does it Happen ?

Spina bifida occurs in the first month of pregnancy, often before the woman knows that she is pregnant. Presently the exact causes of spina bifida are unknown. It is thought that there are both environmental and genetic triggers. By genetic, we do not mean hereditary in the general sense of the term. Spina bifida does not follow direct patterns of heredity like muscular dystrophy or haemophilia, but it is thought to be familial. That is, the genetic influence is expressed by an increased risk of having a child with spina bifida after having a first child with this problem, or if a close relative has has a child with spina bifida (predisposition or 'familial link').

It is known that women taking medication for epilepsy have a higher chance of having a child with a neural tube defect. Genetic counsellors can discuss the risk for each family member. (Contact the Spina Bifida Association for more information.)

There have been reports in the media of a connection between Agent Orange and spina bifida. In the Unitd States an independent review of all available data on the effect of herbicide exposure has been reported. The report found "limited or suggestive evidence" that herbicide exposure in the parents could be associated with spina bifida in their children. Included in the review were a few studies of Vietnam veterans, and some of these suggest the possibility of a slightly elevated rate of spina bifida in the children of Vietnam veterans.