Please have a look at this Pinterest board for outfit inspiration : Maternity What To Wear
WHAT TO WEAR
The most important thing is that you wear something that you feel comfortable in and that is you. A few things to avoid would be loud patterns or prints and logos as they can look really distracting in photos.
A dress / top that is tight at the top above the belly is one option. A dress or skirt that flares out starting just above the belly can look lovely. You don't want it to be tight underneath the belly.
A flowy skirt or dress allows lot of movement which is flattering and gives you something to play with / swish around. If your outfit is a dress, the most flattering is floor length.
Think in terms of tones: blue tones, earth tones, neutrals or pastels. Neutral tones and earthy tones are always a win in photographs. This can be any colour in a muted tone such as forest green, burnt orange, mustard yellow etc. Avoid bright fluorescent colours. Blacks and dark colours are not the best choice for maternity as it does not show the belly well. Mid to light colours are best.
FABRIC TO AVOID
Stiff cotton does not flow nicely and. can get super wrinkly so just be mindful of this one. Stretchy fabric is not flattering, it shows every bump and bra strap etc and I highly recommend avoiding this fabric.
Textures are also beautiful such as lace, linen and knits. They add depth and richness to images.
HAIR, MAKE-UP & NAILS
Whatever will make you feel best, do that. Whatever you normally do is fine, you want to look like you. Nails should be manicured in a light, neutral colour.
FAKE TAN CAUTION
Please be careful with fake tan, if you really feel like you need one, make sure it is as light and natural as possible. Fake tan comes out quite orange in photos and does not go well with your partners skin (and can look patchy on hands).
IN HOME SESSIONS
In home sessions can be all of the above but can also mean a little less clothing. The images can be a lot more intimate with a bit more skin showing. This can be anything from sweaters and jeans to a sweater with undies, jeans and shirtless for the boys! Whatever is you and you are comfortable with and want your photos to be. It can also be less an intimate feel and more of a "loungey" casual vibe or anything really that you have in mind!