Hi. My sister is 20 weeks pregnant. She is only 30, and decided against the NT scan, because she thought the risk was low as we have no history of DS in our family, or her partners family. She had her 20 week scan done yesterday, and the sonographer was worried about the neck measurements. The results came back today, showing she has a 1/300 risk of her baby girl having DS. THe Dr at the Gladstone hospital is sending her done here to Brisbane, and they are rushing her to get another scan done on this Tuesday. If the risk goes down to 1/100 she said her Dr said that was bad. She doesn't really want an amniosyntesis, and she said it doesn't matter if the bub does have DS, she won't be terminating anyway. This is her 5th child, and she is really worried.

The question is, does anybody know the difference between the risks at 13 weeks (with the NT scan) and the risks at the 20 week scan? Because I have heard and read in here that the risks are generally good even if its 1/300 or 1/100. Any help/advice would be much appreciated?