J.,
This is one of the many problems with ultrasounds: they give you information that may have no meaning at all and may raise the level of concern for a mom during her pregnancy interfering with bonding and the joy pregnancy is supposed to bring. As a former direct-entry midwife, I've encountered people who have had such results on their U/S. It often disappears and even when it doesn't, it's not necessarily a bad thing.
Though it's considered a "soft sign" for fetal anomalies, it is considered such because it's not definitely correlated with fetal anomalies. In my mind, it's a correlate with fetal anomalies only like being a pre-born baby is correlated with fetal anomalies. Some now think this may be normal developmental stage that the pre-born baby goes through.
I've been involved in cases where the U/S was so terribly wrong and the parents were strongly encouraged to abort, but didn't and then found out at birth their baby was perfectly healthy.
I'd encourage you not to borrow trouble just yet. The Lord is still in control. Love this baby and encourage your daughter.
D. S (mom to 5, granny to one)