Understanding the results of the triple test can be a tricky business, even for a third pregnancy. Our midwife looks at the figures.

Raisingkids member's problem
I am currently 17 weeks pregnant with my third child. I have just had results from the triple test and it shows I am low risk - 1 in 1300. Last year my results were 1 in 39000. I am now 27 and I'm concerned at the difference, or do you think the figure with my second pregnancy was a typing error? I am confused at how things can change in one year. I know the test says low risk and it's only a estimate but do you think there may be a chance of having baby with Down's as the results are so hugely different in this pregnancy?

Midwife Genevieve Kingston's Advice
Yes the triple test is partly based on your age-related risk, but the rest of the information comes from the blood test. The labs look at various levels of hormones and work out what that level at that gestation gives you a risk of. They then add in your age risk and come out with your individual risk. It can be an improved risk over a previous pregnancy, or a greater risk because each pregnancy involves a new baby which contributes to the hormone levels. As your age increases, the calculated risk increases, sometimes dramatically, so I cannot say whether your risk of having a baby affected by Down's is likely or not.