i had a NT scan at 12 weeks to check for down syndrome, my brother has down syndrome and although his type of down syndrome is not hereditary (there are actually 3 types of ds, one being hereditary) i suppose i was more curious than worried. this is an optional scan though and isnt covered by medicare.
definately get the 18-20 week anatomy scan, this is where they check all bubs measurements, including internal organs etc to check everything is running smoothly, i got most of this back from medicare from what i rememeber. i havent had a scan since then as they said its not necessary unless they diagnose a problem later along the line. GL HTH