During each breastfeeding session, your body will naturally go through two different phases: let down and expression. Understanding each phase can help ensure that your baby is getting enough milk and that your body is making adequate milk for your little one.

Phase 1: Let Down

Once your baby latches onto your breast, he or she will begin to suck vigorously. This fast sucking will stimulate the nerves in your breasts, which signals the release of a hormone called oxytocin. The release of oxytocin will make the small muscles that surround your milk-producing tissue to contract. This contracting of the tissue will squeeze milk into your ducts. Let down typically takes two minutes to occur.

When your milk lets down, you may feel a small amount of pain or tingling in your upper breasts. Many moms describe it as a “pins and needles” feeling. You may see lumps form in the skin around your areola. This is milk that has filled up in the ducts.

Let down can also happen if your brain is mentally stimulated. This can happen by hearing the sounds of a crying baby, looking at a picture of your little one or by smelling a piece of your baby’s clothing. Relaxing and thinking about your baby can signal the release of oxytocin in your brain, which will cause your milk to let down.

Phase 2: Expression

After your milk has let down, you will enter the expression phase of your breastfeeding session. During expression, your baby’s sucking will slow down and you will hear him or her swallowing the milk. As your baby becomes satisfied, their sucking will continue to slow down. Your baby will naturally begin sucking in a “suck, pause, swallow” rhythm as the milk is expressed and their tummy begins to fill.

As your breast empties, your baby may start to fall asleep or may come off of the breast completely. Use this opportunity to take a short break and burp your baby before switching sides and repeating the process.

Your body makes milk based on “supply and demand.” It’s important that your little one remains at the breast through both let down and expression in order to empty your breast as much as possible. This will, in turn, signal to your body that more milk needs to be made.

Foremilk and Hindmilk

Though your body only makes one type of milk, its nutrition and fat contents vary throughout each nursing session. Foremilk is the milk that is released during the beginning of nursing, immediately following let down. It will immediately quench your baby’s thirst as it has a higher water content.

Hindmilk is the milk that comes at the end of the nursing session, during expression. Hindmilk has a high-fat content, which will help your little one feel full and satisfied (and help them develop those adorable baby rolls). If you don’t completely empty your breast before switching sides, your baby may not get enough hindmilk. Always finish nursing on one side before switching to the other breast.

Tips for Moms Who Pump

In order to provide the best milk for your little one and maintain your milk supply, it’s important to experience both phases during each pumping session. It can sometimes be difficult to experience let down when you are away from your baby. Be sure you have  a pump that makes the process easy, so that you can always be relaxed. The following tips may help:

  • Try to relax as much as possible.
  • Bring a photo of your little one to look at while pumping and a small article of clothing. Look at the picture, close your eyes and try to envision your baby.
  • Set your pump to a higher speed with less suction at the beginning of the pumping session. After your milk has let down, increase the suction and slow your speed. This will help mimic your baby’s natural rhythm and help empty your breasts.
  • Pump for 10 to 15 minutes per side, waiting until milk expression has slowed down or stopped completely.


Your body naturally goes through two phases during each breastfeeding session. By making sure that your little one remains at your breast through both phases of breastfeeding, you will ensure that your little one gets all of the nutrition that he or she needs and that your milk supply will be maintained as you continue through your breastfeeding journey.

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