Sarah, first of all the club foot may just be a bad sonographer or your lovely Noah being in a funny position (I know mein kleiner Liebling has done that on our scans), so the second scan may be a lot better for you.

Trisomy 18 isn't a carrier-based genetic illness, it's just a very rare thing that occasionally happens when a cell divides. If you or your DP had trisomy 18 then it would be very hard for you to fall pregnant due to the abnormalies making sperm and eggs harder to make. Even balanced translocations make fertility lower, an extra chromosome is a lot more (stupid word has gone, but noticable-difference-making is what I'm after) than that. If you want to know more on the science side of it, do let me know, but club foot and trisomy 18 do not occur because of something you or your DP has done.

Best of luck for the 15th, less than a week to go, and hope that everything is well and good on the scan.