What is nipple confusion? It's a "first world problem" that happens because sucking on a rubber teat requires a very different mouth and jaw action than sucking on a real nipple.
When babies breastfeed they relax and open the mouth wide. Next, they pull the milk out with gentle peristalsis (a wave of muscular contraction passing from the tip to the back of the tongue). Bottle-fed babies, on the other hand, open their mouths less widely and tend to bite the nipple, between the gums, to promote the flow of formula. (You can imagine how that feels on your nipple!)
How to Avoid Nipple Confusion
It’s best not to use bottles and pacifiers until the nursing is going well. (Although, it’s no catastrophe if your baby gets a pacifier a few times in the hospital.) Once your baby has the hang of nursing, I recommend giving one bottle feeding per day (preferably of breast milk or–if you don’t have enough milk pumped–breast plus some warm water that you previously boiled. But don’t dilute the milk more than once a day. Frequent watered-down feedings are bad for her health.) This way, your baby will learn how to take a bottle from another caregiver, in case you get sick, become unavailable, or have to return to work.
Delay the Bottle...but Not Too Long
If you wait longer than 4 weeks to introduce the bottle, you may be rudely surprised by your baby’s emphatic rejection of the rubber nipple! Once you start bottles, try not to skip more than 1 or 2 days without giving one. (Some babies stubbornly refuse the bottle if their moms take too long a break.)