Breastfeeding Science: Babies Suck

breastfeeding ultrasound
Photo from New Scientist

In early May, Medela hosted the 5th International Breastfeeding and Lactation Symposium in Venice, Italy. During the conference, an ultrasound of a baby breastfeeding was presented along with the findings that milk is removed from the breast when the baby creates a vacuum suction

Exactly how milk is extracted from the breast is important to know when looking at why some babies can't latch along with why breastfeeding is painful for some women.

Maybe I've read too many books on breastfeeding and have friends who might as well be on La Leche League, but sucking? This is sort of common sense, no?


I guess not. Bumpology writer, Linda Geddes, spoke to Donna Geddes (no relation) of the University of Western Australia in Crawley.

"There have been two theories about how breast milk is expressed," Donna Geddes said. " One is that the baby uses a peristaltic or compression motion to actually push the milk out of the nipple and breast. The other theory is that vacuum is primary in removing the milk."

Geddes and her team made a video showing ultrasound images of 20 babies breastfeeding (aged 3 to 24 weeks). They also measured the strength of each baby's suck. The video is 

They found that the milk is extracted best when the baby's tongue is lowered and a vacuum suction is applied. There isn't a milking action, or any pulling of the nipple and breast.

Babies who have trouble breastfeeding have a weaker suction, which ties in with preemies having trouble with latch and babies with cleft palates not being able to nurse.

I had some trouble breastfeeding one of my twins -- she wasn't latching on, wasn't creating that vacuum suction that is necessary. It took a week or so, but she learned.

The team wants to create a test for babies to assess their ability to suck when they are born. This way moms can understand (and not feel guilty or at fault) if their baby has trouble nursing.

Because I had twins, and one who was great at nursing from the start, I understood that this was an individual thing -- my little girl just needed to adjust the way she was trying to feed. Still, I felt at fault. Mother's guilt, right?

Of course, a breast pump can help a mom feed baby breast milk until the baby is strong enough to apply enough suction to properly nurse.

It was also revealed that those women who experienced pain when breastfeeding had infants who had a very strong suck. Some even crushed the nipple when trying to feed. This information can help create more effective nipple shields to help the baby breastfeed and so moms don't have pain.

I love science!

Did your baby have trouble sucking?

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