I am currently taking Lexapro for PPD and it says on the bottle not to take it if you're PG or BF. When I asked my doctor about it, she said it was because not enough research has been done on women who are PG or BF and also taking that medication.
She told me some of the things that other women had had as side effects and that I should also watch my DS and report any and all side effects to the FDA to help them better understand the effects of the med on PG or BF mothers. I am happy to say that neither me or my son have had any side effects from the Lexapro. I hope you have the same experience that i did. Good luck!