The most important thing is to distinguish between ideation and plans. When you talk, you should be crystal clear that you have some ideation and no plan. You do not plan to harm your baby, you do not plan to take your life, etc. etc. Use those exact terms, so the T realizes that you are in the know.

I have never had PPD, but before my second child was born, the day before, I wrote a mildly suicidal letter that frightened the recipient who then notified my doctor. After I delivered my daughter, a psychiatrist came to the delivery room with the intention to assess me and possibly hospitalize me. I said that sure, I had had some bad ideation before but had absolutely no plan atm (or ever had had). And repeated it several times. "No plan". She backed off. I went home with my daughter and breastfed her for four and a half years. Had I been hospitalized without her, she would have been formula fed. So yes, it is very important to stay with the child.