Years ago, I leaned over a beaker of milk and saw something grayish on the top. It smelled like smoke! I concluded it was the nicotine that gets into the milk and seems to be retained in the fattier portion of the milk that floats out of the thinner portion! Prolactin levels tend to be suppressed with smoking and is dose-related; the more she smokes, the lower her prolactin levels. They probably explains in part why many smoking mothers complain of poor weight gain and/or low milk supply. Will baby be addicted and experience withdrawal? I do not know of any studies that have looked at this question. Most pertain to effect on mother. However, Maureen Minchin did a review article that was published in JHL (I think Dece 1992) which may be helpful. As I recall, she also noted gi upset in the babies of breastfeeding smokers. Def. of LC service: "We are all faced with a series of great opportunities brilliantly disguised as impossible situations." Kathleen G. Auerbach,PhD, IBCLC - [log in to unmask]