My baby boy had this diagnosed at his 20 week u/s. The O/b said not to worry as up to 3% of babies get this, & that it can also run in families. It put the chance of him having Down's Syndrome up slightly, but we weren't worried. It disappears by about 24 weeks, & when my little man was born, he was perfect.

I know it's hard not to worry, but try to put it out of your mind & enjoy a happy & healthy pregnancy.