Second trimester style is a little tricky for two reasons.
1. Some women won't really show much at all till the end of the trimester. Some women go through an awkward stage of looking like they are carrying some extra weight around the middle rather than pregnant and other women have a well defined bump from the very beginning.
2. Your perceptions about your body will be changing a lot over this trimester. When you look at your reflection in the mirror, your focus will start to shift from your face and your overall look to your torso-- chest and belly. At the beginning of the trimester you may still be buying and tempted by regular clothes but by the end you may not want to even look at regular clothes. Keep in mind that this means you will be adjusting to a new body image which can be a struggle.

With my first child, I didn't show much in the second trimester and went through the awkward stage at the end. With my son and this baby, I have had a well defined bump all along. So here is my break down for what has worked for me over the second trimester.

Angie says sleek is better for the pregnant body. I agree, and in particular I think there are two areas that you can highlight to accomplish this task. Ideally you should always try to define at least one of these star areas and preferably both.
1. That area underneath the bust and at the top of your belly-- your new waist. This is the smallest part of your torso, so flaunt it. Even if you don't feel like it's all that small, it will be relative to your belly and chest.
2. The curve on the underside of your belly. This helps to define your belly as a cute pregnant bump.

In light of these two basic principles here are my tips for second trimester style.
- Watch your posture! Chances are you are starting to recover from morning sickness when you were often hunched over with nausea. It's good for your back and helps keep that narrow part of your torso visible. The idea is to avoid having your breast just resting on your belly by the time you get to the third trimester.
- Get a new bra if necessary-- by the end of the trimester you will probably have experienced some natural enhancement.
- Highlight your growing chest. Cleavage is inevitable if it wasn't before so you might as well embrace it. Busty women already know the tricks. I'm not busty usually so I can't really speak to this too much but I hope everyone can have a positive attitude about it.
- Correct me if I'm wrong but my theory is that pregnant women can get away with more tight fitting clothes. Obviously, you want to be appropriate, but I think showing off the shape of your hips, behind, or a little cleavage is somehow counterbalanced by having a belly. And it also seems to be a natural manifestation of your current state.
- Tops - I used a mixture of regular and maternity tops during my second trimester. Look for those that are fitted below the bust, below the belly (banded bottoms) or both. I also like to start looking for tunic length tops because I know that by the third trimester, no top will seem long enough especially when the fitted ones seem to ride up all the time. Non maternity tunics also provide a wider selection.
- Dresses - I'm finding that dresses with fuller skirts don't work as well as straighter skirts. Having lots of fabric hanging from your belly makes for a more bulky look
- Skirts are tricky because I really think you want to be defining the under curve of your belly. Pencil skirts seem to work as well as a skirt that drapes well enough to show the curve. This is the reason I like my jersey skirt. Even though it's rather full, it's very light and drapes close to my hips.
- Stretch is your friend. No matter where it is it makes garments more comfortable and more fitted or sleek.
- Pants - I find that I have to go up a size in pants during my pregnancy, towards the end of the second trimester. You will probably want to stick with sleek styles and be sure to pay close attention to leg line. A growing belly means visually lengthening your torso so you will need to compensate in the leg line.
- Jackets and cardigans-- I've heard that the general rule of thumb is that you can wear regular jackets and cardigans, but I think you have to be careful about this. Don't forget that your bust is also growing so you may at least have to size up. I haven't worn too many jackets and cardigans this summer but going through my closet some of my jackets and cardigans look a little too shrunken on my growing belly. Plus, they're uncomfortable because they tend to tilt forward at the neck and shoulders as they are forced open to allow for my belly. Since I have broad shoulders, I'm finding going up a size works for me. Also, the unfitted styles (but still tailored through the shoulders) like trapeze give my belly a little more room.
- Get some maternity work out wear if you've outgrown your regular stuff. I actually find that I can just get regular yoga pants a size up because they are stretchy and usually low rise. Then get some exercise like walking. It will help you feel good, help with digestion, prepare you for birth and make you think about your posture.
- If you have a special occasion and want to make do with something less dressy than you would normally wear simply because you don't want to purchase for one time use, consider having your hair professionally styled for the occasion and go all out with make up. It occurred to me (from Angie) that your hair can really take the ensemble up a notch for these situations.
- Make sure you have some really cushy shoes. Your feet will be supporting a lot more weight in a short period of time and they need a break at least sometimes. Having the right shoes can also help your posture.

I feel like this is not at all comprehensive so please jump in and add your own tips