What happens inside your baby's mouth with breastfeeding?

When your baby's mouth closes over your nipple and breast, the following things happen, if all is going well.

1. A seal is created so that air can't suck into your baby's mouth.

   • The lower half of baby's face buries into your breast, which creates the front part of the seal so that he can't suck air in from the environment.

   • His hard or soft palate and the middle of his tongue touch, which creates a seal so that he can't suck air into his mouth from his airways.

   • A slight baseline vacuum is created, which holds the nipple and breast tissue in your baby's mouth. If your baby has a lovely deep face-breast bury, which is what we're aiming for, you won't be able to see her lips.

2. Then, baby's jaw drops down as a reflex, creating a much bigger vacuum inside your baby's mouth (because it is still sealed from the air). This vacuum applies mechanical pressure to the tissues inside your baby's mouth.

3. In response to the vacuum, your nipple and breast tissue

   • Are drawn further up into baby's mouth, and

   • Expand in all directions.

4. The mechanical force of the vacuum spreads evenly over the surface of the nipple and breast tissue inside your baby's mouth.

5. Each time the little jaw drops, more of your nipple and breast tissue is drawn into baby's mouth until it is as full as possible with breast tissue, and her mouth can no longer close up much at all.

6. At the same time, the sensory stimulation of baby's mouth on your nipple triggers a letdown. When your letdown occurs, the vacuum draws milk drawn out from your milk glands and ducts. Milk is transferred into your baby's mouth because of both the vacuum and the positive pressure of your letdown. You can find out about letdowns here.

That's how it all happens!

You can watch a short animation of how babies suck here, and a long video and animation here.