I think eating more veggies and fruits will help a lot. For example, if I eat two mangos at a time I have to run to the bathroom :-) Try dried pitted proons, they're delicious and nutricious. make sure to have a portion of veggies with each meal. I think the raw veggies are best! We're all in the same boat!
I took over the counter medications, I was on Miralax most of my pregnancy - with my doctor's approval. Also had to take stronger things (phospho liquid stuff) twice - also with my doctor's approval.
Speak to your doctor!
The greatest thing ever created was FiberOne bars. It is in the grocery aisle. For me, when I am constipated I eat two a day as snacks and it helps me get back to normal. Now I make sure I eat fiber rich foods before anything else.
Like adgal said water and fiber will both help with constipation. When it gets really bad the one thing that works for me every time is prune juice. It's all natural and works quickly.
I struggled with it throughout my pregnancy. Increasing your water intake can really make a difference, and staying away from caffeinated beverages. Lot's of fiber in your diet also really makes a difference. I used a natural herbal laxative on occasion along with a stool softener, but make sure you check with your Dr. before doing that. Good luck to you!