Donor Milk Expression Habits: Can we Favor Hindmilk Banking for Extremely Preterm Infants?

Abstract

Background:

Extremely preterm infants often receive donor milk. Hindmilk, which is released more than 3 minutes after letdown, could be advantageous due to its elevated levels of fat and calorie density. Donor milk expression habits may influence milk composition but have not yet been investigated. This study aims to assess the practices of milk donors and the feasibility of hindmilk expression.

Methods:

Active milk donors in Québec were questioned using an online survey about their milk expression habits and whether hindmilk donation would be acceptable to them. Answers were analyzed using mixed methods.

Results:

Of 181 donors, 126 fully completed the questionnaire (70%); 57% reported expressing donated milk between breastfeeds; 15% reported simultaneously breastfeeding while expressing donated milk from the other breast; 12% reported breastfeeding their baby on each breast, then expressing donated milk (hindmilk). The majority (66%) would be willing to change their habits most or all the time to provide hindmilk for preterm infants. The main themes invoked by respondents in open-ended answers were altruism and gratitude for being able to help others. However, 15% commented on the complexity of milk expression or that adding further complexity might discourage them from donating.

Conclusions:

Expression practices are variable, which may lead to variability in donor milk composition. Most donors would agree to change their expression habits in favor of giving hindmilk to help the most fragile infants. More information is needed on how changing recommendations for milk expression might impact the supply and composition of donor milk.

Introduction

Human milk banks are now widely established as sources of donor human milk (DHM) for hospitalized newborn infants whose mothers do not provide sufficient milk for the entire needs of their infants.¹ Compared with Cows’ milk–based formulae, human milk reduces necrotizing enterocolitis incidence in extremely preterm infants and is recommended by professional associations for their first months of life.² Therefore, when maternal milk production is impossible or insufficient, very preterm infants should receive DHM. Altruistic donations come from mothers of infants, mostly born at term, with an excess of milk production, or by bereaved mothers.

There are known differences in milk composition at different stages of lactation,³ from colostrum to mature milk, between milk of mothers who deliver prematurely and those at term,⁴ and even small differences depending on the time of day when expression occurs.⁵ There are also major changes in macronutrient content during each breastfeed, between the foremilk and hindmilk.⁶ Although difficult to define precisely at which point milk becomes “hindmilk”, studies of milk composition have defined hindmilk as that produced after the first 3 or 5 minutes of breastfeeding or expression.⁷ Many studies demonstrated that hindmilk contain a higher concentration of fat^7–12 than foremilk. Takumi and colleagues noted that hindmilk contained almost twice as much fat as foremilk (120.6 ± 66.7 µmol/ml versus 68.6 ± 33.3 µmol/ml; p < 0.05).¹³ In addition to fat, studies have also shown a higher concentration of calories^10,12,14 (between 10 and 35 kcal/100 mL more than whole milk, p < 0.001), vitamins,¹⁰ and GLP, a satiety-regulating hormone.¹⁵ Concerning proteins, study results remain controversial while some see a significant increase in hindmilk compared with foremilk;^10,16 many studies show no statistical difference at all.^12,17–19 Drip milk, that which spontaneously “leaks” from the other breast while feeding from one breast, is particularly low in nutrient density.²⁰

Because of the high and variable nutrient requirements of preterm infants for their growth and development, breast milk (mother’s own milk and donor milk) is routinely enriched with multicomponent fortifiers which contain an energy source, additional protein (usually derived from cow’s milk), minerals, and vitamins.^21,22 Fortification prevents extrauterine growth restriction, which is associated with poor neurocognitive outcomes, and avoids specific nutrient deficiencies.^23,24 A randomized study carried out in 2007 showed that very low-weight babies fed exclusively with hindmilk for two weeks gained weight at an average rate of 12.92 ± 10.94 g/kg per day, whereas babies fed whole milk gained weight at an average rate of 5.01 ± 17.34 g/kg per day (p < 0.0001).⁸ In a more recent study, Alshaikh et al. also demonstrated significant weight gain in babies under 30 weeks of age fed hindmilk for 2 weeks, compared with the period when the same babies were not fed hindmilk.¹⁴ The use of hindmilk DHM could be an innovative strategy to increase caloric content of DHM intended to preterm infants, reducing the need for energy fortification.

In the published literature, there is no information about the expression habits of milk donors: do many of them express foremilk, or the opposite? The advice given to milk donors is also quite variable. For example, in Canada, the Vancouver milk bank proposes expressing once a day, with the assumption that the entire feed will be expressed and donated, but does not explicitly state this or mention timing within a feed.²⁵ The Toronto milk bank suggests expressing “when the breasts feel full, or after breastfeeding your baby”.²⁶ The National Institute for clinical Excellence guidance in the United Kingdom suggests not to donate “drip” milk but gives no other guidance.²⁷ Most milk banks, either public or private, give no specific instruction with regard to timing of expression and collection, other than details of how to maintain cleanliness and how to collect the milk and send it to the bank.

The purpose of this project was to determine the usual patterns of milk expression in mothers donating to the Hema-Quebec Public Mothers’ Milk Bank, whether foremilk, hindmilk, undifferentiated milk (foremilk + hindmilk), or drip milk was being supplied. The second purpose was to determine whether donors would find it acceptable to provide hindmilk.

Materials and Methods

Study population

Héma-Québec operates Quebec’s only human milk bank, which was established in 2014 and maintains a register of active donors, all of whom supply an email address when they register. An electronic questionnaire was emailed once to all the active milk donors in Québec (n = 181) to collect data on their milk expression habits and their willingness to give hindmilk. The study was approved by the Research Ethics Committee of Héma-Québec.

At Héma-Québec’ milk bank, excessive stored milk cannot prompt a woman to become a donor as this milk will not be accepted by the bank. Current procedures require that donors are allowed to give milk to the bank only after the date they have completed the entire registration process, which involve health questionary, blood sample analysis, given information about hygiene practices, etc. This ensures that donors are pumping their milk intentionally for the bank and that these habits, throughout their involvement with the milk bank, are always in line with the bank’s requirements.

Questionnaire

The survey was originally developed to gain a better understanding of donor preference and milk expression habits, to provide information from a strategic and operational standpoint for the milk bank. The questionnaire was reviewed by medical experts, neonatologist and lactation consultant, and parent partners. We also consulted a specialist in mixed methods research who examine parental perspectives. Pretesting was done with a small sample within the milk bank to ensure face validity, as well as a positive user digital experience.

The only inclusion criteria for the study were to be registered with the milk bank (active donor). All participants (n = 181) received an email informing them of the study and inviting them to participate by clicking on a link. To complete the survey, they had to actively click on the link provided, which then redirected them to the online survey webpage—therefore, consent is implicit in taking this action. The survey was only accessible to individuals who received the link through emails. However, no in-survey mechanisms, such as “Captcha”, were used to prevent bots completing the survey. Two versions of the survey were available as follows (see Table 1): one in French and one in English. It was possible to complete the survey, once, in either language.

Table 1.

Questionary and Results

Questions, response options, and distribution of answers
1. In addition to freely donating your milk to Héma-Québec, how many babies are you currently breastfeeding?

Response options	Distribution of answers
One	95.2%	120
Two	1.6%	2
More than two	0%	0
None	3.2%	4
Total		126
2. How often do you express milk for Héma-Québec?

Response options	Distribution of answers
Several times a day	6.4%	8
Once a day	24.6%	31
3–4 times a week	19.8%	25
0–2 times a week	49.2%	62
Total		126
3. How comfortable are you with the techniques recommended by Héma-Québec for expressing breast milk?

Response options	Distribution of answers
Very comfortable	72.2%	91
Comfortable	25.4%	32
Uncomfortable	2.4%	3
Very uncomfortable	0.0%	0
Total		126
4. How familiar are you with the benefits that your donation of milk can bring to premature babies?

Response options	Distribution of answers
Very familiar	53.2%	67
Familiar	37.3%	47
Unfamiliar	9.5%	12
Very unfamiliar	0.0%	0
Total		126
5. Which of these options describes what you do most often when you express milk for Héma-Québec?

Response options	Distribution of answers
I keep one breast for my baby and the other for the milk bank	15.0%	17
I breastfeed my baby (at least 3 to 5 minutes per breast), then express my milk	11.5%	13
I express my milk, then I breastfeed my baby	1.8%	2
I express my milk for the milk bank when I am not breastfeeding	56.6%	64
Other	15.0%	17
Total		113
6. Would you be willing to change your current way of expressing milk as follows: Breastfeeding your baby first on each breast, then immediately expressing milk from each breast for the milk bank?
This practice would not interfere with the benefits of breastfeeding your baby but would better meet the needs of premature babies by providing them with milk that has a higher lipid concentration to help them reach their development goal before leaving the hospital.

Response options	Distribution of answers
Yes, that would be acceptable to me	65.8%	79
No, that would not be acceptable to me	34.2%	41
Total		120
7. How often would you be willing to change your way of expressing milk as follows: breastfeeding your baby first on each breast, then immediately expressing your milk from each breast for the milk bank?

Response options	Distribution of answers
Always	35.4%	28
Often	30.4%	24
Sometimes	22.8%	18
Rarely	11.4%	9
Total		79
Following questions are asked only for statistical categorization purposes and will not be used to identify you.
8. In what age group are you?

Response options	Distribution of answers
18–24	1.7%	2
25–29	21.5%	26
30–34	56.2%	68
35–39	17.4%	21
40–44	3.3%	4
45+	0.0%	0
Total		121
9. How many pregnancies have you brought to term in your lifetime?

Response options	Distribution of answers
Only one	35.0%	42
Two	41.7%	50
Three	17.5%	21
Four	5.8%	7
Five or more	0.0%	0
Total		120
10. What is the last year of schooling that you completed?

Response options	Distribution of answers
Grade school	0.0%	0
High school	2.5%	3
College	19.0%	23
University certificates or diplomas	1.7%	2
Bachelor’s degree	43.0%	52
Master’s degree	25.6%	31
PhD	7.4%	9
I prefer not answering	0.8%	1
Total		121

In addition to questions about their current methods of milk expression and their willingness to change these habits, the electronic survey collected data on donor age, number of pregnancies, current number of babies breastfed, and educational level. In order to improve the experience of donors at Héma-Québec’s milk bank, the questionnaire also had two open-ended questions. Except for the open-ended questions, completion of the survey was defined as obtaining a response to all questions.

Statistical analysis

Participant responses were analyzed using mixed methods.

Results

In total, 126 out of 181 donors (70%) completed the questionnaire and responded to all questions (Table 1), except for the open-ended questions which were facultative (Table 2). No duplication from the same IP address was observed. Among responders, most participants (78%) had a university degree, and 65.0% had had more than one pregnancy. Ninety-five percent were breastfeeding a single baby, two donors were breastfeeding twins, and four were not breastfeeding an infant at the time of donation.

Table 2.

Open Questions and Answers

We invite you to share any comments you have regarding this proposed way of changing how you express milk

It simply needs to be initiated so that the milk starts producing enough to drink and donate. Patients should be informed that this will be done gradually, but that once it’s started, there will be enough milk to drink and donate.

It’s already very complicated to donate to the bank. There are a lot of steps and restrictions. Don’t forget that everyday life with a baby is not easy, so you must want a lot for Héma-Québec to prepare everything for this donation. If it were simpler, I would really have had a lot more milk to give you. And if you add a restriction, it might discourage a lot of moms.

When I express my milk, it changes the quantity I produce, so to avoid producing too much and having engorged breasts afterwards, I express when baby doesn’t drink all the milk (e.g., 1 breast/2).

Expressing milk for the bank after breastfeeding seems more complex. Put baby down, wash breasts, and make sure everything is clean and sterile before giving milk.

My baby now is around the 7 months, he is eating solids, and the takes of milk for him are more quickly than before, so I think it’s going to be very difficult to do that option.

I used to express the other breast while breastfeeding. Doing it right after breastfeeding my baby would be more time consuming from washing my breast before expressing to the expression itself. I don’t know if I’d be able to do it.

I express my milk about 1 hour after my baby is asleep for the night, to make sure he doesn’t need any more milk. Then I pump for the bank!

I express my milk at night or early in the morning when I’m engorged. I produce enough milk to nurse from one breast at a time.

As I have 4 children at home, it was easier for me to pump at the same time than to nurse on one breast. What’s more, my daughter only took one breast for her feeds. It’s not the benefits of this procedure that I don’t like, it’s just the difficulty of doing it in my situation.

It’s more difficult to pump milk when the ejection reflex is weaker. As a result, I get a better yield when I express first and my baby is far more adept at extracting the remaining milk than the pump.

I’d be put off by the complexity of the hygiene and the method. This should be left to the discretion of mothers, those who are comfortable could do it without it being an obligation to keep as many donors as possible.

I pump my milk when my children are in bed, so I wouldn’t have time to pump after breastfeeding when there’s a lot going on around the house.

I prioritize my baby, who has a delayed weight gain of her own, which is why I rarely do this for the time being. But once she’s caught up with her weight, I’ll be able to do it more often.

I would have liked to have been informed that fat milk at the end of the feed is more beneficial for premature babies from the start, as this change is very easy to adopt, and I have already given several dozen bottles of breast milk. I’ll be adopting this technique for future bottles!

I incorporate expressing milk at the end of the day when the children are in bed. Expressing my milk takes about 20 minutes (the whole technique plus the time it takes to pump and clean up afterwards) and my baby doesn’t often tolerate being 20 minutes without being in mom’s arms.

The suggested method takes longer.

With my second, I only expressed the “excess”. The engorgement of the first months/weeks. By sterilizing my “milk saver” each time, and obviously having cleaned my breast well beforehand, I collected the “flowing” milk from the other breast that wasn’t breastfeeding baby. As time went by, it became more difficult to continue donating milk. For my 3rd, having a complete cleft lip and palate, breastfeeding was impossible, so I did what I always do: pump. In order never to run out of milk, I keep a good “advance/overproduction” of milk. I get absolutely no benefit from storing all this milk; it’s immensely more useful for premature babies.

It doesn’t change much for me.

My child only drinks from one breast at a time and doesn’t want to know about the 2nd when I introduce it, so the option isn’t really an option for me!

I’d like to make it clear that this way of expressing myself is acceptable. However, it’s not my way. I express my milk to relieve congestion only, so I don’t do it after a feed. But for those who pump regularly, I think it would be a simple habit to change.

My boy often drinks later in the morning. But my breasts are often very full, so I express milk for comfort.

It takes some time to get the breast pump and other accessories assembled, so I do it when someone else can watch the baby or the baby is sleeping.

I pump almost exclusively, so I only breastfeed at night, and I don’t pump at night, sleep is important!

I do it at the same time, so one breast the baby hasn’t touched yet and the other one has. I’m careful not to have too many restrictions, which could have discouraged me because it’s getting more complicated and taking longer to drink (I’ve got a three-year old at home too).

That’s what I already do if I understand the suggested way.

I usually express milk from one breast only for Hema-Quebec, so I don’t have to wash both breasts before pumping.

Could be done occasionally or encouraged but can be difficult to do in certain circumstances (e.g., mom from the neonatal unit I was part of at the beginning of the donation) and now I express my milk before going to bed to include in her meals for the next day (this is currently when I express milk for donations) about 2 to 3 hours after the last breastfeeding. It would be possible to change habits but might limit the amount of milk donated.

I’d like to point out that I haven’t been making bran for a few months. I responded according to the last times I gave milk. The difficulty in expressing AFTER is that someone must be available to look after the baby.... The other option is in the evening when baby is asleep, but I’m often too tired.

The only problem I see is that my baby won’t have access to the end of my milk, which contains more lipids and is good for him too.

I don’t have enough milk to feed my baby and express afterwards, so I must wait for the breast to fill up. Also, as the procedure is quite long (sterilizing everything, cleaning the breast) I do it when my baby is asleep. I would have liked to give more, but with 3 children and not so much surplus milk, I give what milk I can (and the time it takes!).

If I were breastfeeding, this method would be very acceptable, but I pump exclusively to bottle-feed my baby. I never breastfeed.

With 3 preschoolers at home, it’s hard for me to extend my breastfeeding periods to express milk. I have about 10 minutes at a time to do it.

I’m going to try to do it, but it’s a bit longer than the method I’ve found for myself. But if you say it would be good for premature babies, I’ll do it.

Since you must clean the breasts before expressing milk for Hema-Qc, it would prolong the process of nursing my baby first and then expressing right after. Also, right after breastfeeding, my breast is usually empty and my baby usually only drinks one breast at a time.

I always express my milk at the same time of day to get a good volume, so if my baby is close to a feed, I get him to drink first, especially if this is the recommendation.

My baby only feeds on one breast per feed, so I’ll feed before expressing, but only on one breast.

It depends on how engorged my breasts are when I wake up.

The problem is that my baby never takes both breasts. I produce a lot of milk, so I also have a lot of less concentrated milk before I get to the richer milk. I must pump 100 ml per breast before the richer milk arrives. On the other hand, it would be easy for me to identify the bottles of richer milk for you.

This way of doing things, however, would mean that I’d have to use my breast pump more often than the silicone haakaa. That’s why I’ll do it less often, unless there’s a way of washing the breast between feeding and expressing my milk that means I don’t have to go back to the sink.

My baby is almost 1, so he’s drinking a lot less. I’ve got into the habit of expressing my milk in the morning when I wake up, and I empty both my breasts for Héma-Québec. My baby doesn’t drink in the morning, so I can start the day with empty breasts, so they don’t engorge too quickly during the day. All I have left are the late-night, evening, and night feeds with my boy, and he doesn’t ask for any for the rest of the day.

It’s more difficult now that my baby’s grown up (10 months), as this would have been possible when he was smaller. I was already doing it for my personal milk bank and on the recommendation of my lactation consultant, with the precious help of my mother-in-law and my partner to look after baby while I pumped.

It makes sense.

I use a Haaka hand pump to express my milk while my baby drinks from the other breast. It’s the ejection reflex that makes the milk flow into the pump. If I had to wait until after feeding, I’d have to get out my electric breast pump, which I don’t have the time to do now.

I always offer breast to my baby before expressing the milk, but what can I do if baby is not hungry and refusing to eat? I just express then.

It would seem difficult to do, given that baby often falls asleep at the breast for his nap after a feed. In the best of all possible worlds, I’d like to give the best milk to premature babies, but as I also have another child, I express my milk when I can.

I pump with the haaka, so after feeding my baby on the breast, there wouldn’t be enough “pressure” to extract enough milk.

I don’t have to change my habits because I already give all my expressed milk to Héma Québec when I pump.

Since my baby recently started daycare, I plan to pump my milk when she’s away to keep up production. So, at that point, I’ll continue to pump when I’m not breastfeeding, but I’ll start pumping after I’ve nursed my baby.

I breastfeed my baby for as long as he needs. Immediately afterwards, I wash my breast and pump my milk for Hema-Quebec. I used to do it every morning. After the first feed in the morning.

I express my milk this way, so I can pump 2–3 oz in a few minutes versus expressing barely 1 oz in 15 minutes when I do it after baby. I imagine that by doing so, my production would adjust. But when I pump first, I have a milk surge and then my son manages to stimulate another surge, whereas when I’ve just breastfed, the pump fails to trigger another let-down reflex and it’s interminable.

I pump for HQ when my baby is away (e.g., daycare) or asleep for a long time to relieve engorgement.

I won’t be able to do this as often as I’d like because it takes a lot of time to sterilize the equipment in my breast pump, and because I have a very busy schedule.

After breastfeeding, I’m too tired to express my milk.

I didn’t think it was possible; I always expressed milk after my shower because I thought my breasts had to be clean.

My baby never drinks both breasts at the first feed in the morning because I have so much milk in each breast when I wake up. As she doesn’t drink much at night, I’m left with some engorgement in the morning if I don’t give her one breast and express the other.

After my baby’s feeds, there’s no more milk coming out of my breasts when I pump...

I’m going to try to take my son off before his feed is finished so that I can pump again. But baby often drinks everything, which prevents me from giving after a feed. I almost must create a fictitious drink to make donations...

I need both my arms to take care of my baby once he has drunk. If I’m busy pumping my milk after he’s drunk, I can’t look after my baby properly. When I’m younger it might be doable, but when baby starts crawling and walking on all fours it’s difficult.

I’m afraid I won’t be able to pump at all after breastfeeding my baby on each breast...I feel like I must wait about 2 hours after breastfeeding to pump a good 50 ml for HemaQc, so I don’t know if I’d be able to get out a min. of 20 ml right after breastfeeding...!

It is just not feasible for me. I do exclusively pumping. But I keep one breast for milk bank: pump what’s needed for my baby and the excess amount for milk bank.

More complex because often we must put the baby to sleep, and this will be at the same time as all the washing / cleaning of hands and breasts.

I pump my milk only, I never put my baby to the breast. I pump around 1900 ml to 2000 ml a day and baby drinks less than 800 ml a day. I dedicate one of my shots to Héma-Québec so I can give 2 a day, starting with one. If you want, I can throw away the first 5 minutes and keep the rest of the milk for Héma-Québec.

I’ll qualify my answer, I can do it more. It happens a few times already, but when my other children are present and I’m alone, it’s hard for me to do the technique, so I prefer not to give my milk.

I’ve never pumped in 3 and a half years of breastfeeding, and I don’t want to start. I don’t see when I’ll have the time to do it.

It’s more convenient for me to do it this way. My baby also needs this fat to grow and develop properly.

I breastfeed my baby from one breast at a time because I produce so much. I kept the 2nd breast for Héma-Québec. I pump when I have time, so right after breastfeeding my baby is not always optimal.

I’ll be happy to change my habits.

I couldn’t do it that way because I don’t breastfeed my baby, but I give him my pumped milk in a bottle. So, for me, pumping milk for two different reasons at the same pumping session would require a lot more work as I’d have to change the whole equipment, clean my breast again to make sure it’s sterile and everything. I think that because I do breast pumping, this technique isn’t really suitable. However, since a pumping session takes about 30 minutes and I pump until my breasts are empty, the pumped milk is very rich in lipids.

For the moment, my baby only takes one breast at a time...so it’s a bit difficult to modify.

I express at night because my baby sleeps (do these at nights) and I have engorgement. I can’t express during the day when I’m breastfeeding my baby.

Very nice experience for me.

Hygiene is very important but very demanding. I don’t have enough time to do both regularly.

We invite you to share any comments you have regarding your experience as a mother’s milk donor with Héma-Québec

It was a pleasure to help you. Unfortunately, I didn’t have too much surplus and time this time, but your work is very important. Thank you so much!

It was a wonderful experience. I find it unfortunate that some medications are not compatible with donation, even though they are recognized as safe for breastfeeding, such as sertraline.... Sporadic home pick-ups by Héma-Qc (1x/month or as requested by clients) should be offered in the regions... or arrange for mobile blood drives to collect the bottles, because driving 50 minutes on the highway to carry milk... you really must want it and be convinced.

Overall, incredibly positive. Highly proficient, great staff who answer the phone is a sweat heart.

I’d love to can do more bottles at week but sometimes it’s very difficult to me.

I was very surprised at how easy it was to become a donor. I think that if breastfeeding women knew that the process was simple, there would be more women interested. Have a great day!

I found the process a little long before my request was accepted at the beginning of my breastfeeding. As my production had adjusted for my baby, I was able to give less milk than if I had pumped in the first weeks of baby’s life. As this is my 4th breastfeeding, I would have felt very comfortable starting from the beginning. Thank you very much, I hope my donations will be used to help premature babies.

It was a wonderful experience. I plan to do it again with my second child.

I’m very happy that the milk bank is now available in my region and I’m happy to be able to contribute to the health of premature babies!-Suggestion: I’d like to have the option of updating my health information online via a questionnaire or similar every two months. This would be easier for me than phone calls.-Suggestion: Reduce the size of the box of empty bottles given out at the beginning. My aim is to give them all to Hema-Quebec by the time my baby is a year old, but the large number of bottles might frighten/discourage some moms at first, in my opinion.

It was a nice experience; I hope I’ll be able to do it again.

They were wonderful.

I find it a bit complicated to have to wash and dry my breasts beforehand.

Thank you for being there for premature babies!

I loved the experience! I’ve been lucky enough to be in contact with moms who’ve had very premature babies and I’ve loved the testimonials.

I feel great giving milk. Thank you for allowing premature babies to have breast milk.

Super organization for the collection.

Very gratifying experience.

This questionnaire could consider the fact that some women do not breastfeed and exclusively pump their breast milk.

It would be very important to provide more flexible time slots for updating (early mornings, evenings, or weekends).

I’m very proud to do this for little babies.

Very simple process and done without pressure. I appreciate the support provided by Hema-Qc!

I feel very useful doing this.

It would be nice to provide a reimbursement for pump rental.

I’m proud to be able to make these donations, but unfortunately, all too often during my 3 breastfeedings, I’ve had to throw away my bottles simply because I didn’t have the time or the organization to carry them. If I had a collection service in more rural areas, I would have almost doubled my donations. I still have 4 bottles in my freezer that I’m going to have to throw away, as they’re expressed in September-October. So no, I love my experience.

I love it, but I know that confidentiality makes it difficult, but I’d like to have more statistics on the impact of donating milk. Number of babies who benefit, how many drink a premature baby, how often, etc. I’ve been lucky enough not to come across any parents or have a premature baby myself, but it’s been one of my fears and that’s why I do it to help those in need. I’d like to understand my impact even more by having anonymous testimonials in a newsletter or something.

Donating breast milk is a wonderful experience for me, and I’m very happy to be able to help babies and mothers in need.

It’s a very rewarding experience and the service is perfect.

The nurses and delivery people are very nice. The whole process was not too complicated.

I love giving my milk to help babies who haven’t had a good chance to start in life.

I loved my experience; I will do it again with my next baby.

Thank you, but it was much more difficult with my 2nd baby because there were ++ illnesses at home... and my baby was intolerant of bovine protein, so I mostly pumped for him in the end, since he didn’t take dairy products...

I think it’s very well organized! On the other hand, it’s always a bit of a challenge to reach you by phone.

Overall, a very positive experience and I wish I could have donated more. My baby was in the after birth, and it would have been very convenient to have integrated Hema Quebec’s set up protocols directly with the hospital (ie blood test, getting a doctor to sign some forms, etc.)-I think this could be the case with other NICU mothers as well (who also may produce more milk than a premature baby needs AND who may be highly willing to donate given their experience with premature babies!)

Thank you!

I feel blessed to have the chance to make these donations and help little babies and, by the same token, other parents.

This is my 2nd year donating breast milk. Although I don’t donate as much as I’d like, I sincerely believe that every drop counts in helping premature babies.

The overall experience has been excellent. However, I did have a few problems with the delivery people. On one occasion, a deliveryman came to collect the milk without a freezer box from Héma-Quebec. Another time, a deliveryman wanted to give me milk instead of collecting mine. Another time, the deliveryman was supposed to pick up my milk and at the same time bring me new bottles; unfortunately, he hadn’t received the message and didn’t have the new bottles. Perhaps the deliverers need more guidance or clearer instructions.

I would like more information on the impact of my donations on the lives of premature babies. Héma-Québec would benefit from partnering with breastfeeding organizations. I needed a breastfeeding sponsor and no one in my area knew of the existence of milk donations (so couldn’t promote them).

It’s a great program, but unfortunately not very well known. There should be more advertising, and mothers who donate milk should receive their bottles earlier to express our milk. Although I signed up very early, I received my first bottles when my baby was over 2 months old.

It would be interesting to have the statistics on the quantities of milk collected per year at Hema-Québec. I was wondering about the size of the milk bank in Quebec.

I loved pumping my milk for the little premature babies, but I must admit I’m not sure how much good my donations do.

Very good so far!

Half of donors (49%) were expressing milk for the bank less than three times a week, for 20% it was three or four times a week, 25% every day, and the remaining 6% expressed several times a day.

Overall, 98% were comfortable or very comfortable with current recommendations on milk expression (hygiene, storage, etc.), and 91% were aware or well aware of the benefits of human milk for preterm babies. Concerning their expression habits that they were most likely to use: 57% reported expressing milk for banking between breastfeeds; 15% reported expressing milk for banking from one breast while keeping the milk from their other breast for their baby; 12% reported breastfeeding their baby on each breast and then expressing hindmilk for banking; and 2% expressed for the bank and then breastfed their baby.

Among the “other” responses, nine mothers reported that they exclusively expressed milk (“exclusive pumpers”) for their own baby: they gave their baby expressed breast milk and gave the surplus for banking. One mother reported collecting drip milk.

The majority (66%) of participants reported that they would be willing to change their habits most or all the time to provide hindmilk, and another 23% said that they would be willing to do so sometimes.

Most mothers (63%) gave additional suggestions in the open-ended question. The main theme invoked in open-ended answers was altruism and gratitude at being able to help others. Many (48%) participants justified their answers, for example, “I am an exclusive pumper, I never breastfeed. I pump about 1900 mL per day and my baby drinks less than 800 mL. I could throw away the milk I pump for the first few minutes if that would help” or “I am afraid that there will be no milk left after I have breastfed my baby on both breasts.”

A few participants (15%) commented on the complexity of milk expression or reported that adding further restrictions might discourage them from donating, such as having to wash both breasts again after breastfeeding to express milk for the bank.

Discussion

To our knowledge, these are the first published data regarding how mothers, donating their milk to a public milk bank, are expressing their milk. There are also no published data to determine whether mothers would be willing to change their approach to provide hindmilk. To produce DHM with a higher calorie density for the very preterm infant, the preferential use of hindmilk, rather than foremilk or undifferentiated milk, may be an advantage.

We have demonstrated the variety of methods currently in use by breast milk donors. In view of the lack of recommendations about pumping habits to donors, we think it is likely that such variability is universal. Previous studies have demonstrated the extremely variable calorie density and fat concentrations of DHM²⁸; our own quality assurance projects have shown a range of calorie density of donated milk between 58 and 73 kcal/100 mL, using standard methodology. Part of the variability in composition is probably due to variation in timing of expression, with some mothers already donating hindmilk, with others donating foremilk, undifferentiated milk, or drip milk. A substantial proportion of donors would be willing to attempt to supply hindmilk. The altruistic nature of milk donation would be reinforced for some mothers by being able to give milk which is even more beneficial for the preterm infant. The possible additional complexity of washing the breasts after breastfeeding, to then immediately pump hindmilk for the bank, was a concern of many who were unsure whether they would be willing to do so.

Most of the milk donated to public human milk banks is used for preterm infants, with the remainder being used for various other babies, such as those living with short bowel, gastroschisis, or congenital heart disease. The main proven advantages are for the very preterm infant who is at risk for Necrotizing Enterocolitis (NEC), in whom there is evidence that the incidence of NEC is reduced, compared with the use of cow-milk formula,²⁹ either when DHM is used as a supplement to mother's own milk (MoM)³⁰ or for babies who do not receive MoM.³¹ Despite these known advantages compared with formula, DHM contains, on average, less fat and less protein than MoM from mothers who deliver preterm.³² Composition is also very variable between donations in these components, and milk from several donors is routinely pooled in order to provide DHM with relatively stable protein and calorie composition.³³ Such pooling is the recommended standard approach of the Human Milk Banking Association of North America and is followed by Héma-Québec.

To better meet the nutritional requirement of very preterm infants, a DHM with higher fat content, such as hindmilk donation, would be useful. Sixty-six percent of responders indicated that they would be enthusiastic to change their milk expression habits most or all the time to provide hindmilk to preterm babies. However, this survey’s question was biased as it suggests that this method would better meet the needs of premature babies by providing them with milk that has a higher lipid concentration to help them reach their development goal before leaving the hospital. This explanation of the effects of hindmilk on the health of preemies should not have accompanied the question, as it may have influenced participants’ answers. This percentage (66%) could be revised downwards if hindmilk donation was put into operations at the milk bank.

Implementation of hindmilk donation would require a consistent supply of hindmilk from donors. Such hindmilk could then be processed and pooled separately and used to supply for the most at-risk infants (e.g., babies weighing <1,000 g), or, if limited in availability, for a subgroup such as those with intrauterine growth restriction or those with postnatal growth failure. This would increase the complexity of the DHM program and, therefore, will require feasibility studies before instituting such a program. It will also be essential to ensure that an option of hindmilk expression did not inhibit donors who felt unable to provide such hindmilk from participating in the program.

The high response rate of 70% highlights the willingness of our donors to help and the trust they have in the milk bank. The education level of breast milk donors is also much higher than in women in the general population of Quebec (78% with university studies versus 33%).

Conclusions

The methods used by donors when providing milk to our milk bank were very variable, and some mothers were already providing hindmilk. Many donors would be willing to provide some or all their donations as hindmilk, although the option to donate undifferentiated or foremilk should be retained to maintain the donor pool. Further work, to confirm that a supply of hindmilk targeting the infant at highest risk of growth difficulties can be provided within our public system and that such a program provides DHM with higher calorie density and similar or higher protein content, without disadvantages to the supply chain, is required. Moreover, more evidence into preterm infant outcomes fed with hindmilk DHM is needed before any change in our milk bank processes.

Footnotes

Acknowledgments

The authors thank all the donors who donate milk to Héma-Québec’s Public Mother’s Milk Bank and those who participated in the survey.

Authors’ Contributions

Descriptions are accurate and agreed by all authors: M.G.: Conceptualization, Methodology, and Writing—Review & Editing; A.J.: Conceptualization, Methodology, Writing—Original Draft, and Writing—Review & Editing; K.J.B.: Formal analysis, Writing—Original Draft, and Writing—Review & Editing; G.M.: Conceptualization and Methodology; C.S.P.: Project Administration; D.F.: Conceptualization, Methodology, and Resources; M.C.C.: Conceptualization, Methodology, and Resources; A.L.: Formal Analysis and Writing—Review & Editing; C.R.: Conceptualization, Methodology, Writing—Review & Editing, and Supervision.

Disclosure Statement

The authors have no conflicts of interest to report.

Funding Information

This project has been funded by Héma-Québec.

References

Israel-Ballard

, LaRose

, Mansen

. The global status of human milk banking. Matern Child Nutr, 2024; 20(Suppl 4):e13592; doi: 10.1111/mcn.13592

Committee on Nutrition, Section on Breastfeeding, Committee on Fetus and Newborn. Donor human milk for the high-risk infant: Preparation, safety, and usage options in the United States. Pediatrics, 2017; 139(1):e20163440; doi: 10.1542/peds.2016-3440

Dror

, Allen

. Overview of nutrients in human milk. Adv Nutr, 2018; 9(Suppl 1):S278–S294; doi: 10.1093/advances/nmy022

Mimouni

, Lubetzky

, Yochpaz

, et al. Preterm human milk macronutrient and energy composition: A systematic review and meta-analysis. Clin Perinatol, 2017; 44(1):165–172; doi: 10.1016/j.clp.2016.11.010

Paulaviciene

, Liubsys

, Molyte

, et al. Circadian changes in the composition of human milk macronutrients depending on pregnancy duration: A cross-sectional study. Int Breastfeed J, 2020; 15(1):49; doi: 10.1186/s13006-020-00291-y

Charpak

, Ruiz

, KMC Team. Breast milk composition in a cohort of pre-term infants’ mothers followed in an ambulatory programme in Colombia. Acta Paediatr, 2007; 96(12):1755–1759; doi: 10.1111/j.1651-2227.2007.00521.x

Bishara

, Dunn

, Merko

, et al. Volume of foremilk, hindmilk, and total milk produced by mothers of very preterm infants born at less than 28 weeks of gestation. J Hum Lact, 2009; 25(3):272–279.

Ogechi

A-A

, William

, Fidelia

B-T

. Hindmilk and weight gain in preterm very low‐birthweight infants. Pediatr Int, 2007; 49(2):156–160.

Valentine

, Hurst

, Schanler

. Hindmilk improves weight gain in low-birth-weight infants fed human milk. J Pediatr Gastroenterol Nutr, 1994; 18(4):474–477.

10.

Bishara

, Dunn

, Merko

, et al. Nutrient composition of hindmilk produced by mothers of very low birth weight infants born at less than 28 weeks’ gestation. J Hum Lact, 2008; 24(2):159–167.

11.

Modi

. The implications of routine milk fortification for the short and long-term health of preterm babies. Semin Fetal Neonatal Med, 2021; 26(3):101216.

12.

Saarela

, Kokkonen

, Koivisto

. Macronutrient and energy contents of human milk fractions during the first six months of lactation. Acta Paediatr, 2005; 94(9):1176–1181.

13.

Takumi

, Kato

, Nakanishi

, et al. Comprehensive analysis of lipid composition in human foremilk and hindmilk. J Oleo Sci, 2022; 71(7):947–957.

14.

Alshaikh

, Festival

, Reyes Loredo

, et al. Hindmilk as a rescue therapy in very preterm infants with suboptimal growth velocity. Nutrients, 2023; 15(4):929; doi: 10.3390/nu15040929

15.

Larson-Meyer

, Schueler

, Kyle

, et al. Appetite-regulating hormones in human milk: A plausible biological factor for obesity risk reduction? J Hum Lact, 2021; 37(3):603–614; doi: 10.1177/0890334420954160

16.

Van Sadelhoff

, Mastorakou

, Weenen

, et al. Differences in levels of free amino acids and total protein in human foremilk and hindmilk. Nutrients, 2018; 10(12):1828.

17.

, Sun

, Liu

, et al. Differences in the content of human milk oligosaccharides between foremilk and hind milk. Food Bioengineering, 2023; 2(2):105–113; doi: 10.1002/fbe2.12049

18.

Khan

, Hepworth

, Prime

, et al. Variation in fat, lactose, and protein composition in breast milk over 24 hours: Associations with infant feeding patterns. J Hum Lact, 2013; 29(1):81–89; doi: 10.1177/0890334412448841

19.

Mitoulas

, Kent

, Cox

, et al. Variation in fat, lactose and protein in human milk over 24h and throughout the first year of lactation. Br J Nutr, 2002; 88(1):29–37.

20.

Arnold

. A brief look at drip milk and its relation to donor human milk banking. J Hum Lact, 1997; 13(4):323–324; doi: 10.1177/089033449701300419

21.

Talebiyan

, Belfort

. Human milk fortification for very preterm infants: Toward optimal nutrient delivery, neonatal intensive care unit growth, and long-term outcomes. Clin Perinatol, 2023; 50(3):625–641; doi: 10.1016/j.clp.2023.04.001

22.

Arslanoglu

, Boquien

C-Y

, King

, et al. Fortification of human milk for preterm infants: Update and recommendations of the European Milk Bank Association (EMBA) Working Group on Human Milk Fortification. Front Pediatr, 2019; 7:76.

23.

Senterre

, Rigo

. Reduction in postnatal cumulative nutritional deficit and improvement of growth in extremely preterm infants. Acta Paediatr, 2012; 101(2):e64–e70; doi: 10.1111/j.1651-2227.2011.02443.x

24.

Hay

, Ziegler

. Growth failure among preterm infants due to insufficient protein is not innocuous and must be prevented. J Perinatol, 2016; 36(7):500–502; doi: 10.1038/jp.2016.85

25.

Provincial Health Services Authority, BC Women’s Hospital. Donating Milk. 2024.

26.

The Rogers Hixon Ontarion Human Milk Bank. How to Donate Breast Milk. 2024.

27.

National Institute for Health and Care Excellence (NICE). Collecting Milk for Donation, 2024.

28.

John

, Sun

, Maillart

, et al. Macronutrient variability in human milk from donors to a milk bank: Implications for feeding preterm infants. PLoS One, 2019; 14(1):e0210610.

29.

Quigley

, Embleton

, McGuire

. Formula versus donor breast milk for feeding preterm or low birth weight infants. Cochrane Database Syst Rev, 2019; 7(7):CD002971; doi: 10.1002/14651858.CD002971.pub5

30.

O’Connor

, Gibbins

, Kiss

, et al. Effect of supplemental donor human milk compared with preterm formula on neurodevelopment of very low-birth-weight infants at 18 months: A randomized clinical trial. JAMA, 2016; 316(18):1897–1905; doi: 10.1001/jama.2016.16144

31.

Colaizy

, Poindexter

, McDonald

, et al. Neurodevelopmental outcomes of extremely preterm infants fed donor milk or preterm infant formula: A randomized clinical trial. JAMA, 2024; 331(7):582–591; doi: 10.1001/jama.2023.27693

32.

Gates

, Hair

, Salas

, et al. Nutrient composition of donor human milk and comparisons to preterm human milk. J Nutr, 2023; 153(9):2622–2630; doi: 10.1016/j.tjnut.2023.07.012

33.

Young

, Borman

, Heinrich

, et al. The effect of pooling practices and time postpartum of milk donations on the energy, macronutrient, and zinc concentrations of resultant donor human milk pools. J Pediatr, 2019; 214:54–59; doi: 10.1016/j.jpeds.2019.07.042