I tried a couple of different kinds (Carlsons and Isotonix) before going with the Rainbow Light brand - which were recommended to me by my midwife, as well as a couple of pregnant friends. I LOVE them! First of all, after just a couple of days, I could poop again. The iron they use really is non-constipating, unlike some of the other brands.
They have two different types. A one a day, called "Just-Once Prenatal", that you take only once per day. After reading several reviews, I decided these might be a bit too large for my swallowing preferences. But some people did say that even though they are big, they had no problem.
I decided to go with their "Complete Prenatal System" instead. They work great for me. You do need to take 6 per day, but they aren't huge, and I've found them easy to swallow with lots of water. I try to split them up throughout the day, taking 2 at each meal. But often I forget to take them at breakfast, or to bring them with for lunch, so end up taking all 6 after dinner. Surprisingly, they have NEVER bothered my stomach doing it this way at all!
The fact that they are food-based, versus made of synthetic vitamins, makes all the difference. It also included your daily probiotics and many other supportive herbs and supplements that aren't included in most other brands. I found them on Amazon for over 50% off and ordered a big enough bottle that I also got Super Saver shipping! It was actually a better discount for me than ordering with my "health care provider" 50% off discount and having to pay for shipping. So check it out!