a study of 1223 amniocenteses carried out during 1020 pregnancies in 990 women showed that 2nd-trimester amniocentesis at about 16 weeks ' gestation is a safe , accurate and reliable procedure for the diagnosis of certain classes of genetic disease when it is monitored by ultrasound , performed by a trained obstetrician and carried out in a major health sciences centre .
C0032961
pregnancies
C0032980
2nd-trimester