<P> Neural tube defects ( NTDs ) are a group of birth defects in which an opening in the spinal cord or brain remains from early in human development . In the 3rd week of pregnancy called gastrulation , specialized cells on the dorsal side of the embryo begin to change shape and form the neural tube . When the neural tube does not close completely , an NTD develops . </P>
<P> Neural tube defects ( NTDs ) are a group of birth defects in which an opening in the spinal cord or brain remains from early in human development . In the 3rd week of pregnancy called gastrulation , specialized cells on the dorsal side of the embryo begin to change shape and form the neural tube . When the neural tube does not close completely , an NTD develops . </P>
when do neural tube defects occur during pregnancy
when do neural tube defects occur during pregnancy
the 3rd week
the 3rd week