Is bifidobacterium infantis safe for pregnant or breastfeeding women?

Probiotics. Probiotics are considered safe but it would be recommended that you ingest them through yogurt instead of through a tablet or supplement.
Don't know. There is not much data on probiotics and other such supplements in pregnancy. I think the safest way to ensure good bacteria symbiosis is to eat unprocessed food and to avoid overuse of antibiotics.