If you really want MF, then I can tell you my 6x4.5 Bronica ETRSi has low mirror slap noise, considerably less than the earlier ETR series cameras, and the older 100/4 macros, which go to 1:4, are not expensive and easy to find. Or an extension tube can be used with a longer lens. The 6x6 SQ series is another option, with the older 110 macros also going to 1:4.
The Pentax 645 is fairly quiet, particularly the mirror slap, though it does have the winder noise.
I second that!Congratulations and I'm so glad she'll going to make it. I'm sure she is a beautiful baby!