Nhs dating pregnancy
It involves a blood test and measuring the fluid at the back of the baby's neck (nuchal translucency) with an ultrasound scan.
This is sometimes called a nuchal translucency scan.
Instead, you will be offered another blood test between 14 and 20 weeks of pregnancy to screen for the risk of Down's syndrome.
As a result, most people, including health professionals, will date your pregnancy based on your LMP (last menstrual period) instead.Your first ultrasound scan, called your dating scan, will give you a more accurate due date for your baby.The person performing the scan (sonographer) will measure your baby from his head to his bottom.This means that he will be one year old during his second year of life. You can change your mind and withdraw your permission at any time.Similarly, when you complete your first week of pregnancy, you are one week pregnant. Different countries may have different data-protection rules than your own.
Find out more about the combined screening test for Down's syndrome.