Anencephaly, a rare, tragic birth defect, causes infants to be born missing parts of their brains and/or skulls. The number of cases in Washington state has recently skyrocketed lately, and epidemiologists are uncertain what is causing the fatal condition. 

An investigation of health records in three counties of the Evergreen State revealed 23 cases of anencephaly in 36 months, between January 2010 and 2013. This translates to a rate of 8.4 births out of every 10,000. That is four times the normal occurrence for the rare disorder. 

No major organization has yet made a goal of finding the source of these deaths. Environmental factors are often responsible for birth defects. 

Anencephaly begins in the first month of pregnancy, before most women realize they are pregnant. Like spina bifida, it is classed as a neural tube defect (NTD). Spina bifida is characterized by incomplete closure of the spinal column, and usually results in partial paralysis beneath the waist. 

During early stages of fetal development, a "neural tube" forms and closes. This structure creates the skull, brain, and spinal cord in babies. In cases of anencephaly, most of the skull or brain never forms.  Those fetuses who are not stillborn, die soon after birth. 

One of the challenges presented to potential researchers is the lack of consistent medical records. While one doctor might ask if a person's home is near a landfill, another might fail to ask. This makes it difficult, at best, to gather accurate data. 

"Medical record reviews might not have captured all information, preventing a cause from being identified," the Department of Health for Washington State wrote in a press release. 

The exact causes of neural tube defects are not yet known. Data collected so far say mothers are more likely to have affected babies if they are obese, have uncontrolled diabetes, or take certain anti-seizure medications. The National Institute for Health recommends adequate levels of folic acid for women who may become pregnant. 

Sara Barron is a nurse who first noticed the spike in cases. After seeing two such births in a short period of time and her hospital, Barron asked colleagues in other parts of the state about cases of anencephaly. She found examples of such birth defects were being seen in other Washington-state hospitals. Barron has been critical of the response from the state since she noticed the spike. 

In 2013, the Centers for Disease Control and Prevention looked at case histories of 27 women who had given birth to babies with NTD conditions.

Researchers asked the women about living habits and possible risk factors. 

"No statistically significant differences were identified between cases and controls, and a clear cause of the elevated prevalence of anencephaly was not determined," the study reported. 

This a a mystery yet to be unraveled, and the lives of babies are at stake.