This is called nursing strike or nipple confusion.

Don't let the threat of "nipple confusion" scare you away from using bottles, especially if your babies are doing well with breastfeeding.

If a pacifier is introduced too early, there's the risk of nipple confusion for a baby who's just learning to nurse, says Shu.

Nipple confusion.

Nipple confusion occurs when a baby is bottle-fed too soon, and then forgets how to nurse on mom's nipple.

(To avoid nipple confusion, many lactation experts recommend that parents wait 3 to 4 weeks before introducing a bottle.)

Starting bottle-feeds before 2 weeks of age often results in nipple confusion - the baby has difficulty changing between the different sucking patterns required for the different types of feeding.

Specialized teats are marketed that report attempting to mimic the shape of the breast to help babies to switch back and forth between bottle feeding and breastfeeding for cases where "nipple confusion" occurs.

Other reasons to pacify a baby primarily at the breast include superior oral-facial development, prolonged lactational amenorrhea, avoidance of nipple confusion, and stimulation of an adequate milk supply to ensure higher rates of breastfeeding success."

"Nipple confusion is less of an issue if you tickle the baby's upper lip with the bottle's nipple and let the baby do some of the work," says Catherine Watson Genna, IBCLC, a New York City-based international board-certified lactation consultant.