the 2872 second trimester amniocentesis followed by amniotic alphafetoprotein ( afp ) estimations carried out in south wales between 1973 and 1981 on women known to be at increased risk for neural tube defect ( ntd ) and those who had a raised serum afp level in an ntd screening programme led to the identification of 78 pregnancies of a fetus with anencephalus , 61 with 'open ' spina bifida , 8 with gastroschisis , 3 with exomphalos , 2 with encephalocele and 6 with chromosome abnormality .
C0032980
second trimester
C0032961
pregnancies