Is it safe to take sodium lactate while pregnant or breastfeeding?

Yes. Sodium lactate is a simple compound that is easily metabolized and does not pose a risk to the baby.
Category C. As far as i can tell, there is a lack of supporting data for use or ingestion of sodium lactate in pregnancy. It has not been found to be harmful or useful, either way. If you don't have to, don't ingest it. If you need it in a hospital setting, then it is safe. I recommend fresh, organic foods prepared by a trusted source...Not just during pregnancy, but all the time. Eat well! :-).