Maternal age
Nuchal translucency
Fetal heart rate
Serum biochemistry
New ultrasound markers
- Nasal bone
- Facial angle
- Ductus venosus flow
- Tricuspid flow
Screening for chromosomal defects
Every woman carries a risk of having a baby with a chromosomal defect
- The average risk depends on the age of the mother
- The average risk is then modified by the results of the ultrasound scan and blood test carried out at between 11 weeks and 13 weeks and six days to derive the individual risk to the specific pregnant woman