Before we list these factors, let us be clear than breast milk, fresh or frozen is immeasurably better for your infant nutritionally than formula; but to use the best at it's very best, we are explaining the changes that happen to frozen breast milk.
1. Levels of pH are effected by freezing which in turn effects lipase which aids in digestion. Lipase levels vary from woman to woman, so if you notice a soapy smell or metallic taste to your frozen breast milk, it may be especially relevant to you to give freshly expressed breast milk.
2. Bactericidal capacity of stored refrigerated human milk is at it's greatest within the first 48 to 72 hours of refrigeration. (By the way, this is good to know so you can use fresh breast milk on your infants or toddlers hands instead of harmful alcohol based hand sanitizers.)
3. Breast milk is age appropriate. Levels of nutrients, most of which we still do not fully understand change with your baby's age. One example is magnesium which increases after 4-6 months. Magnesium aids in bone development which is needed especially in infants as they begin to sit, crawl and pull-up.
4. White blood cells in breast milk are living leukocytes and are killed during the freezing process. These white blood cells are prevalent in freshly expressed breast milk and help prevent infection and disease.
5. Antibodies are another reason freshly expressed milk is best. If a mother has recently built immunity towards the latest illness going around, this is passed along to her nursling. So it is especially important to give freshly expressed milk during the cold and flu season.
6. Energy density of breast milk varies with the age of the baby. So giving a 6 month old breast milk expressed at 4 months, is not as beneficial to his energy needs as giving fresh breast milk.
5. Nutrients have been shown to decrease when breast milk is frozen over time. One study showed a decrease in Vitamin C after breast milk had been frozen for 3 months.
Now that you know some of the reasons that freshly expressed breast milk is best, how can you as a working mother or an exclusively pumping mother manage it.
- First know that all breast milk, fresh or frozen breast milk is superior to any formula.
- If you are a M-F working mother, leave frozen milk for your baby on Monday but use the milk you pump Monday to give on Tuesday, Tuesday's milk is for Wednesday, etc. Then when you come home on Friday, feel free to freeze that milk or save it in the refrigerator for Monday depending on how much stockpile you think you need in the freezer.
- Frozen milk is perfect for use as a back-up and if you see you have more than you need, please donate it!
- If you are an exclusively pumping mom and need to dip into your frozen stockpile, don't beat yourself up about it. You are doing so much good for your baby in giving breast milk. To help you have more fresh milk in the future, make sure to simulate growth spurts by pumping 11-12 times a day during the week your baby turns 3 weeks, 6 weeks and 3 months. Also, make sure you use stopwatch on your phone or timer app to ensure you are double pumping for a full 10-15 minutes, whether milk is flowing the whole time or not. This will help you get the stimulation you need to keep up a healthy milk supply. Also don't forget to change valves, diaphragms or filters on your pump often to get the best performance out of your pump.
- Unless you are keeping you rmilk at room temperature and using it within the next 6-8 hours, you will need to plan to keep your milk cold to transport it. Use only hard ice packs as they stay cold longer than soft ice packs do. Invest in a breast milk cooler tote that holds six bottles. If you have six bottles, you are pumping into new containers each time and can chill the milk before combining it which is the safest method.
- Many products are dedicated to freezing breast milk, but new products are helping moms label and organize their freshly expressed breast milk. Breastmilk Bandit is an economical re-usable and fun way of helping moms with this task with their breast milk organizer. These are day of the week bottle bands that say Mommy's Milk and the day of the week in fun colors. Also helps identify your baby's bottles in the church nursery or day care. Breastmilk Bandit Breast Milk Bottle Bands fit most 4-8oz breast milk storage and feeding bottles.
Lawrence R. A., and Lawrence R. Breastfeeding: A Guide for the Medical Profession. 6th ed. Philadelphia, Pennsylvania: Mosby, 2005: pp. 106-129
Per Gaskin, Ina May. “Soapy-, Metallic- or Rancid-tasting Milk that You Have Thawed.” Ina May’s Guide to Breastfeeding. New York: Bantam, 2009. p.165.
A few studies have found a significant decrease in vitamin C levels in frozen milk after 3 months Buss et al., 2001; Bank et al., 1985
Martínez-Costa et al., 2007
EFSA Journal 2013;11(7):3331
Goldman AS. The immune system of human milk: antimicrobial, anti-inflammatory and immunomodulating properties. Pediatr Infect Dis J 1993 Aug;12(8):664-71