This does not seem like a path to success. I certainly would advocate exploring other formats as part of your growth and path as a photographer, but not as a marketing gimmick. A good picture is a good picture whether its taken on a phone, a $30k medium format digital camera, or a large format film camera. Ultimately your clients will be drawn to you because of the quality and style of your work, not what camera you shoot it on. I'd much rather have a huge grainy wall print from an enlarged 35mm neg of a great photo, than a tack sharp grainless enlargement from a boring 8x10 neg.

And even if there is a market for those looking for maternity photographs who are looking for that large format quality, lets say for every active member on this board, there are 100 other people in the US who appreciate the quality of large format (either technical or aesthetic either of which I would say is very nuanced/unnoticeable to the not photo-obsessive), so that's 3500*100= 35,000 which is 0.1% of the population. So assuming the market for maternity photos is roughly representative of the general population, you're looking at 1 in 1000 clients who might even notice the difference in the image when produced on large format. And the non-image novelty factor of working with someone who uses a view camera will quickly vanish when the reality of that process is revealed to them.

don't get me wrong. i love film. and i really like large format (albeit i'm still quite new to it). But I think this is neither a smart marketable aspect, nor a particularly smart choice of format for working in maternity/newborn photography professionally (the odd job here and there on large format is way different than working day in and day out). And as much as i like film, i wouldn't chose a photographer because they worked in film, i would chose them because i think they are good photographer!

That being said... I do think that if you shot wet-plate, with a great big ol' wooden camera and brass lens, and made the whole thing an experience which resulted in a one-off collodion image that maybe got housed in something like they would put old Daguerreotypes, I think there's a market for that. The logistics of that on newborn sound like a nightmare, but I personally would pay for that if you were good enough to get the baby to go consistently to sleep to allow for a long exposure image (or got clever with artificial lighting that wouldn't practically explode the baby's retinas).