Obstetric dating calculator
Your baby's head, limbs, hands, and feet can be seen, as well as his abdominal wall and some organs, such as his stomach.
Screening for Down's syndrome involves a nuchal translucency (NT) scan plus a blood test. You can have the combined screening test from 11 weeks to 13 weeks plus six days, or when your baby's CRL is 45mm (1.8in) to 84mm (3.3in). If you prefer, you can have a private screening test. As well as the combined test, most private healthcare clinics offer non-invasive prenatal testing (NIPT), which is the most accurate (up to 99 per cent) screening test for Down's Syndrome. For example, the NT scan for Down's syndrome has a false-positive rate of five per cent. This means that, out of 20 women who have the scan, one woman will be wrongly told she has a high chance of having a baby with Down's syndrome.