The NT is the small collection of fluid at the back of the baby’s neck that the sonographer will measure if they identify that it looks big or if you have asked for screening for Down’s syndrome (T21), Edwards’ syndrome (T18) and Patau’s syndrome (T13).
Most babies where the NT measures 3.5mm and above will have no other health concerns. However, it is more likely that these babies could have certain issues, which the health professional will have discussed with you. One of these is that the baby is slightly more likely than most to have a chromosomal condition.
You may have chosen to have screening for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome and the midwife or obstetrician may have discussed the result of this test with you.
You will be offered chronic villus sampling (CVS) or amniocentesis to see whether your baby has a chromosomal condition. Both of these tests have a small risk of causing a miscarriage.
Having a CVS or amniocentesis carries an additional risk of miscarriage which is likely to be below 0.5% (around 1 in 200) of pregnancies. The additional risk of miscarriage following CVS or amniocentesis in a twin pregnancy is around 1% (1 in 100) of pregnancies.
Other findings on the early pregnancy dating scan – the health professional will discuss the findings of the scan with you and tell you which tests they will offer. They will tell you which sections of this booklet are relevant to you.