There are 2 commonly used screening options available for antenatal screening for Down syndrome and other conditions. Antenatal screening is particularly recommended if you are 35 years of age or older as the risk for conditions such as Down syndrome increases with increasing age of the mother.
The 2 options now available include first trimester combined screening and second trimester maternal serum screening. The screening tests are able to pick up most cases where there is an increased chance that you are carrying a baby with Down syndrome, Turner syndrome, Trisomy 13 or Trisomy 18. Occasionally it can also pick up that you could be at risk of a pregnancy-related health condition.
First trimester combined screening
This screening is available if you are less than 14 weeks pregnant and includes a blood test and an ultrasound scan. Results from both the blood test and the scan are combined with other information like your age, weight and baby's gestational age (how many weeks pregnant you are) to come up with a relative risk score.
- The blood test is best taken at 10 weeks, but can be taken between 9 weeks and 13 weeks and 6 days.
- The ultrasound scan (also known as a nuchal translucency scan) is best done at 12 weeks pregnancy, but it can be done between 11 weeks and 2 days and 13 weeks and 6 days.
- Read more from the National Screening Unit.(external link)
Second trimester maternal serum screening
This is a blood test, best taken between 14 and 18 weeks but it can be taken up until 20 weeks. This test looks for the levels of 4 analytes (chemicals) in your blood. From these levels, a low or increased risk score is calculated after considering your age and related factors. Read more from the National Screening Unit.(external link)