Info for druggie sister?

My sister had her baby 3 months ago. She is feeding and on the weekend she had a babysitter mind her little boy for a few hours while her and I went to a small party. This was the first time she's been out since the birth. At the party I noticed her acting a little strange and on our way home she told me she had taken speed at the party! What I'm wondering is the effect this would have on her boy if she's feeding? She promised it was a one off but I'm not believing her for a minute. I'm totally devastated and need some info to p on to her. Thanks for your help!