M.L.
Constipation isn't just a side effect of Zofran... it's the side effect of pregnancy in general as well as prenatal vitamins, especially ones high in iron.
I've taken Zofran for all 3 pregnancies and never had a side effect issue with it besides fatigue (which is also a general pregnancy symptom). If you choose between nausea and constipation, just choose whichever one is less harmful that you can deal with the best. For me, my nausea was so bad I had to take Zofran or else I would have been hospitalized. Metamucil is supposed to help soften stools.
I would also look into changing your prenatal vitamin, because that could be a cause too. Definitely talk to your Dr. about that. Also, here is some good advice on reducing constipation during pregnancy:
http://www.americanpregnancy.org/pregnancyhealth/constipa...