Ok, sorry, facts this time.
It seems fish oil is recommended from prior to conception to promote healthy eggs etc. The EPA and DHA from Omega 3 such as good quality fish oil, is vital to the growth of babys brain, eyes and nervous system- therefor taken all during pregnancy. Taken during third trimester is important as it can help with babys reaching full term, being a healthy birth weight, also to help reduce high blood pressure in mum and can assist in reducing the likelihood of post partum depression. Some women who eat a lot of oily fish, dont need the supplement, but you have to be careful not to consume too much high mercury containing fish (which fish oil doesnt have) Also be careful with things like cod liver oil which contain too much Vit A.
Go to www.oilofpisces.com/pregnancy.html
It has an overview of some of the studies from around the world regarding this subject.
It seems most say there needs to be more research of course, but studies always show an improvement in mothers and babies taking a supplement. Sorry about the guess at late trimester causing bleeding- definitely couldnt find anything to back this up- ask your obstetrician or doctor.
I think I will go and take mine now!