Nipple confusion is the term some people use to describe the difficulty some babies have trying to breastfeed after being fed by a bottle. It happens in some babies and not others. Nipple confusion is most likely to happen in the first few weeks of life, and some say it is most likely when the mother has flat or inverted nipples because exposure to a firm, protruding bottle nipple changes a baby's expectations. Because your baby won't be born with a label telling you whether or not he's susceptible to nipple confusion, many lactation consultants recommend avoiding bottles before four to six weeks of age if possible. After several weeks of nursing, nipple confusion is much less likely to be an issue.