amniotic samples from 25 mid-pregnancies ( 15-17 weeks ' gestation ) with neural tube defects ( 14 with open spina bifida and 11 with anencephaly ) and from seven mid-pregnancies with abdominal wall defects were compared with a control material consisting of 80 amniotic fluid samples from 80 consecutive mid-pregnancy amniocenteses , with normal karyotypes and afp concentrations .
C0027794
neural tube defects
C0002902
anencephaly