There is a thread about that. Just recent too. If you do a search or just scroll through today's threads, you should find it.
Ponderosa Pines are the ones you want to avoid. Their needles contain turpentine and eating them will cause abortions in bred goats, and cattle at least. As far as I know, all other pine trees are ok.Heard a while back but don't know if its true.
If so when in the pregnancy is it more dangerous?