Hi J.
Sorry to hear about your rosacea.... I have a mild version and have found several things that help and hinder!
Don't wash your face with hot water.... this makes it much worse! Only use lukewarm or cold. This also means that lots of steamy hot baths will make it worse too.
The sun really triggers it for me. Make sure you put on lots of sunscreen if going out in sunny weather.
They say alcohol makes it much worse but I guess being pregnant that's not it for you!
There is a really great skin care company called MyChelle - everything they make is so pure you could eat it (literally!) no chemicals whatsoever, and they do a wonderful calming serum for rosacea which I use:
http://www.mychelle.com/news/calming_serum.htm
They have great customer service so if you phone them they would be able to confirm if it was all right for you to use. Many stores like whole foods carry their range but I find it cheaper on line.
I hope this helps and all the best of luck!
N.