Is it safe to take xolair while pregnant or breastfeeding?

Yes. There is no evidence that Xolair with affect anything during breast feeding. There is experience in the EXPECT registry of 199 women who received Xolair during the first trimester and they have not noted an increase in any problems. If you are currently pregnant and took Xolair within a month of getting pregnant, go and register and share your experience.
Yes. Animal studies show that it is not associated with birth defects. It is assumed that this drug passes into breast milk and the effect on infants is unknown, so be very cautious. However, there is a risk of a severe allergic reaction in anybody using it, so, it should only be used in pregnancy if clearly needed.
Probably. The drug xolair has been shown to be safe in 2d and 3d trimester of pregnancy. I personally do not use it during the 1st trimester but studies showing harm are not published.