Is baby acne more likely if the baby is being fed?

My daughter is 4 1/2 weeks old and she has got these fine bumps all over her face and neck. I'm pretty sure that its not a heat rash as I make sure that she's not to hot or overdressed. I was searching for the answer to my question and I had seen that somebody had said that the bumps were baby acne from hormones ped by the mother and that it's most visible in -fed babies. Is that true? If so, how long till the bumps clear?