How to pump breast milk and store it in a bottle.

For mothers who are going to leave their babies in nurseries or daycares during their working hours.

You can continue feeding your baby breast milk by pumping milk and storing it in a bottle.

How often should the mother pump her breast milk? Research suggests the following methods:

According to the duration of the child’s stay in a nursery away from his/her mother.

1. Within 4 hours …The mother doesn’t have to pump her breast milk.

2. 4 to 6 hours …We encourage the mother to pump her breast milk at least 1 time.

3. Over 8 hours…We encourage the mother to pump her breast milk every 3 hours.


According to some research results, a mother’s breasts can keep producing the same amount of milk if she pumps her breast milk regularly.



There are 2 ways to pump breast milk. You can pump them with your hands or with a breast pump. If you select the breast pump method, we encourage you to choose a breast pump which allows you to adjust the suction pressure easily and efficiently.


What should you do when you don’t have enough time to pump your breast milk in your office?

You should pump your breast milk with your hands for 5 minutes to prevent congestion in your breasts in the morning and in the afternoon, and throw the milk away. At lunch time, you should pump your breast milk for 20 to 30 minutes, and you may keep the milk. If you do not pump your breast milk and your breasts become congested, you might contract mastitis.

Before you go back to work, you should practice pumping your breast milk.


  • You should wash your hands with soap and running water for at least 15 seconds before touching your breasts.
  • You should practice pumping your breast milk 7 to 14 days before going back to your office, and you can keep the breast milk in stock.
  • You should practice pumping each breast 2 times in the morning 1 hour after nursing your child.

You may increase your stock by pumping your breast milk when they become engorged in the middle of the night.

Even after your child has nursed, milk still remains in your breasts.

How to safely treat pumped breast milk  

    1. Use a sterile container every time.
    2. Record the date and the time on the container.
    3. Use an amount of milk which the baby can consume at one feeding.
    4. You can keep breast milk in a freezer which is under -20°C at your home for up to 12 months, but preferably, it should be consumed within 3 to 6 months. Once thawed, never re-freeze.
    5. You can keep breast milk in a fridge up to 8 days, but preferably, it should be consumed within 2 to 4 days.
    6. For healthy babies, you may reuse breast milk which has been warmed up once and kept in a fridge below 4°C and for less than 4 hours.
    7. Even if you cannot put breast milk immediately into the fridge, you can put it in afterwards if the room temperature is below 25°C and was left out for no more than 6 to 8 hours.
    8. Please do not mix breast milk and formula milk. Mixing reduces the efficacy of the antibacterial and immune-active substances and the absorption of minerals which are contained in breast milk.
    9. When you give frozen or refrigerated breast milk to your child, warm the breast milk in tepid water, about 37° Do not warm breast milk by microwave oven.


What is “frozen milk”?

Sterilized bags are available at drugstores (such as Tsuruha or Sapporo Drug Store). You can keep your breast milk in the bags in a freezer for up to 12 months as long as the temperature is -20°C or below. (However, it is best if the frozen milk is consumed within 3 to 6 months.)


What is “refrigerated milk”?

You can keep breast milk in clean bottles in a regular refrigerator. It will keep for up to 7 days. (It is best to consume it within 2 to 4 days.)

☆ Kin-ikyo Sapporo Hospital☆