Done by Anencephaly Study at Duke University Medical Center
Approximately 2% of babies with anencephaly will have a chromosome anomaly (a difference in the number or structure of the chromosomes). Testing for chromosome anomalies is possible via amniocentesis or collection of a fetal blood or tissue sample at delivery.
Environmental factors such as obesity, diabetes, certain medications, pesticides, maternal fever and folic acid deficiency have been implicated in contributing to anencephaly. Additional unknown environmental factors also likely play a role.
Anencephaly is caused by failure of the cranial end of the neural tube (fetal structure that develops into brain and spine) to close by day 28 of gestation.
After having one pregnancy with anencephaly, the chance to have a second pregnancy with an open neural tube defect is approximately 3%. Meaning 1 in 33 women will experience a second affected pregnancy.
Humans have approximately 20,000 genes. Genes are the instructions or blueprint for our body. We get half our genes from our mom and half from our dad. Changes in genes likely contribute to the development of anencephaly.
Anencephaly is more common in girls. Approximately 2 in 3 babies with anencephaly is a girl.
Every woman of childbearing age should take 400 micrograms of folic acid daily to reduce the risk of fetal open neural tube defects. Women with a previous pregnancy with anencephaly should take 4,000 micrograms (4 milligrams) of folic acid daily prior to subsequent pregnancies.
Anencephaly is caused by a combination of multiple genetic (inherited) and environmental factors. Unfortunately, most of these factors are not known.
Learning more about the genetic causes of anencephaly may lead to the availability of genetic testing for at-risk family members and potential new preventative measures.
Anencephaly can be seen on ultrasound by the 12th week of pregnancy.