Saturday, April 2, 2011

Infant Physiology and Milk Transfer

This topic is too broad to be thoroughly addressed in a blog, but I can definitely comment on the area and encourage those in the learning mode to continue to examine this very important discipline.  

Ascertaining that the infant actually breast feeds is very crucial to the role of the Lactation Consultant.  It sounds pretty elementary, but it is amazing how many infants wind up with jaundice or failure to thrive due to mismanagement of breastfeeding.  It's not actually breastfeeding that is the problem in most of these cases, but starvation.

When a mom delivers, she has a wonderful synergy of hormones that are adjusted perfectly for bonding and breastfeeding.  The two hormones that are present for only a short time are oxytocin and estrogen--a combination that assists in bonding (Uvnas-Moberg, The Oxytocin Factor, 2005).  While pregnant, the mother has progesterone which inhibited milk production, but with delivery, a  radical withdraw of progesterone and estrogen gave way to high levels of prolactin which enabled milk production (this is another reason to have a mom examined for retained placenta if she does not enter lactogenesis II and has heavy bleeding beyond the 3-4 day).  

The prolactin is the milk producing hormone, but nipple stimulation releases oxytocin which is the milk ejection hormone.  Oxytocin is often referred to as the "love hormone" since it is elicited through stimulation.  Initially, stimulation is necessary to release the milk, but over time, stimulation is less relied on.   If we allow Baby to turn oxytocin on (baby led attachment)  The following timeline is observed: (MatthiesenBirth, 2001)

  6:  Baby opens eyes
11:  Massages breast
12:  Hand to mouth
21:  Rooting
25:  Moistened hand to breast
        Nipple becomes erect
27:  Tongue stretches & licks nipple
80:  Breastfeeding

Other hormones necessary for the production of breast milk include: insulin, cortisol, thyroid hormone, parathyroid hormone, parathyroid hormone-related protein, and human growth hormone.

Once the hormonal process is well underway, we must turn our attention to the act of breastfeeding. Milk transfer is necessary to feed the baby and to ensure mom continues to make milk. If baby is unable to empty the breast, mom should be encouraged to hand express to finish the process. If the breast is not emptied, it is in jeopardy of slowing production. A full breast not only will not make more milk, it can even inhibit milk production (this is a good time to refresh your memory on the FIL or feedback inhibitors of lactation). 

Often babies will self-latch and feed within a few hours after delivery. Medications and interventions can alter the schedule, but ideally a mom and infant left together to bond will have a successful time breastfeeding (remember the laid-back technique for easy and biological breastfeeding).

Measuring milk transfer can be as easy as noting the babies behavior. Is baby having 1 wet diaper on day 1 (24-hour period), 2 on day 2, 3 on day 3...6-8 on day 6 and beyond? That is one indicator of milk transfer.
The scale is also a good tool to use (especially for the premature infant). Pre and post test weights can assure milk transfer has occurred.

The infant test-weighing procedure should be performed using an electronic digital infant scale with accuracy to at least 2 grams. The infant is weighed clothed pre- and postfeeding without changing the diaper between weight measurements. The prefeed weight is subtracted from the postfeed weight, and the difference represents the volume of milk consumed, where 1 gram of weight is equivalent to 1 mL of milk intake. Milk is slightly denser than water, so in theory this calculation overestimates the test weight results, which is countered by insensible water loss during feeding.
Milk transfer is an area of concern and we must make sure early on that the infant is being fed. Know signs and symptoms of dehydration and make sure early follow-up appointments are kept. Unfortunately, I have to say, many lactation consultants, including myself, have witnessed mismanagement of feeding to a point of readmission to the hospital. Let's educate parents and keep our eyes open to possible warning signs.

For more detailed description of oxytocin and prolactin visit

For visible cues of milk transfer, visit