During the first weeks of pregnancy, a fetus develops a structure called a neural tube along its back. The top of the tube eventaually develops into the brain, while the rest of the tube becomes the spinal cord. Neural tube defects (NTDs) occur when the neural tube does not close properly during brain or spinal cord development.

There are two major types of NTDs: Anencephaly and spina bifida. Anencephaly is a severe and usually fatal defect that occurs when the skull and brain fail to develop. Spina bifida is an opening along the spine that exposes the spinal cord. Children with spina bifida often have problems like paralysis and loss of bowel and bladder control.

Only 1-2 of every 1,000 live births will have neural tube defects. You are at higher risk for having a child with an NTD if you have a family or personal history of neural tube defects, or if you have already had a child with an NTD.

However, 95% of all babies with NTDs are born to couples with no known personal or family history of the condition.

When your fetus is 16-20 weeks old, your doctor may offer to perform a Maternal Serum Alpha-Fetoprotein (MSAFP) profile to check for neural tube defects and Down syndrome.

During an MSAFP profile, a small amount of blood is taken from your arm and measured for three chemicals (alpha-fetoprotein, estriol, and human chorionic gonadotropin). If the level of these chemicals is higher than normal, it may mean that your baby has a neural tube defect. However, it can also mean that your fetus is older than expected, or that you are carrying more than one fetus. Your doctor will offer additional tests (like an ultrasound or an amniocentesis) to evaluate the health of your baby.

If you do learn that your fetus has a neural tube defect, your doctors and counselors will help you understand your options and find more information.

If you are planning to get pregnant, talk to your doctor about taking a multivitamin with folic acid. Folic acid has been shown to reduce the risk of having a child with a neural tube defect.