Pregnant mothers have yet another substance to avoid.

Though the Food and Drug Administration (FDA) has approved the use of drugs containing valproate for migraine headaches, epileptic seizures, and manic episodes of bipolar disorder, it is now warning pregnant women to steer clear of valproate products as recent findings show they may cause cognitive birth defects.

A recent study by Dr. Kimford Meador and colleagues, published by the Journal of the American Medical Association, illustrates that prenatal exposure to valproate-containing drugs increases the risk of childhood autism and, relatedly, negatively impacts the IQ scores of children.

The research has not established specific time points within a pregnancy that valproate exposure can have the most effect. However, if the drug is affecting cognitive development, and perhaps causing mental retardation, the FDA is taking a necessary precaution to forewarn mothers of the drug's effects on their children.

Autism and cognitive defects are often a result of changes to one's genes. Often, drugs work at the level of gene expression to change which genes are turned on or off, altering the types of molecules made in the rest of the body, which can be positive if the change allows for the manageability of seizures.

If pregnant mothers take drugs, like valproate, that alter their gene expression, their unborn children may also experience the same change in gene expression. However, children may not have the same needs as their mother, and the change in the expression of certain types of molecules may prove to be deleterious rather than positive for them, causing cognitive deficiencies like autism and mental retardation.

This finding suggests that women whose conditions cannot be managed without these drugs should consider an effective birth control regimen.

The FDA is currently working with manufacturers who package valproate-containing drugs to ensure this new warning is reflected on labels.