1) The looped hair-elastic trick - this is mainly for the first and second trimesters, when your bump is small but you can't button up your trousers. You can still wear your button front/zip trousers - just take a hair elastic and loop it around the button hole. Keep the zip open and fasten your button through the hair elastic - and then wear a LONG tank or tunic to cover up your exposed skin. If you're not a fan of DIY, you could buy something like a Belly Band.
2) Have a sufficient number of cute post-delivery clothes - It's important to feel good about yourself as your body is going through so many changes. This is one thing I wish I had focused more on. I didn't purchase a lot of maternity clothes - I bought some maternity dresses (like the black one in my picture above) and layered them with pieces I already owned. This was fine during the pregnancy, but after the birth, my pre-baby clothes didn't immediately fit me, and my maternity clothes were too loose. You're already feeling exhausted - you don't want to feel frumpy too - so a little pre-planning and pre-shopping can go a long way. I'd recommend purchasing a couple of flowy tops and stretchy pants - keep it cheap and cheerful, as you're probably going to get spit up on....a lot!
3) Wear a bra ALL the time - Your cup size will change repeatedly - during pregnancy, during nursing and after you wean your baby. If you're well-supported during all these changes, you may be able to prevent sagging. I wore cotton sports bras a lot during my pregnancy, since I couldn't keep up with all the different cup sizes. As there is no underwiring, it was quite comfy to sleep in. Here's some more info on preventing sagging by sleeping in a bra.
a wedge pillow at Thyme Maternity (my exact one pictured below) AFTER my delivery to help with back pain, and it was a HUGE help...I can only imagine how great it would have been DURING my pregnancy under my bump.
6) Regaining your pre-baby body - it's very important to keep fitness and healthy eating in mind - without obsessing over it. It's better to focus all your energy on your newborn, and let your body naturally settle down after birth. By the time your baby is sleeping through the night, you'll probably have the time and energy to focus on exercise (after getting your Dr's permission). Since the stomach muscles have been put under so much strain during pregnancy, you need to strengthen your core and be VERY aware about the way you exercise. Conventional sit-ups can lead to "tummy-pooching" as you have to firm up your deeper abdominal muscles first. I HIGHLY recommend Lindsay Brin's Core Firing Sequence method. This program is designed for mothers - and offers maximum results with minimum effort. She has 3 levels of exercises. Each level takes 10 minutes: you only need to do one level, and move up as you get more confident. I've done level 1 and 2, and find that I get surprisingly defined abs even when I just stick to level 1. Combine these tummy exercises with cardio a couple of times a week, and you will get great results.
Do you have any pregnancy tips to share? Did you get stretchmarks? Do you know how to get rid of them?