Hi Jas
Congrats on your pregnancy
I was reading up on this last night (what to expect when you are expecting i am finding it easy to read and informative cheapest at kmart $26.95) apparently it is quite normal to have variations from normal either way (diahorrea to constipation) with digestion its a response to the different hormones milling around your body. From recollection the author suggested trying to play with your diet a little to minimise foods which are very proactive in encouraging digestion (too much dairy, some fruits too much sugar that sort of thing) Sorry i can't remember too much more detail than that.
If it continues incessantly perhaps chat with your dr about it to make sure it is nothing more sinister?
Cheerio
Belinda.