Suck, swallow and breathe

Baby's tongue is key

Though suction is important in breastfeeding, the baby's tongue was found to be key. Once the baby latches and their mouth creates a baseline vacuum, the tongue is lowered to increase vacuum and allow the nipple to expand evenly, deep into baby's mouth. Ultrasound and vacuum measurements taken while breastfeeding showed that this is the moment milk flows.

When baby lifts the tongue again, vacuum lessens and milk moves to the back of the oral cavity. After one or more sucks, it's time to swallow. Now baby stops breathing for 0.5 seconds, swallows - and the cycle can begin all over again.

The studies confirmed the role of the tongue in removing milk from the breast. Instead of using peristaltic motion, the anterior part of the baby' tongue becomes rigid and expands the nipple evenly. Peristaltic motion takes place in the posterior part of the tongue, which is also plays a role in swallowing.

As babies mature, they become more efficient at breastfeeding, apparently without changing their tongue movements or levels of vacuum. One idea is that, as baby matures, the mid-tongue moves more, to handle increased milk production and flow.

Variable ratios

The 1:1:1 SSwB ratio, based on bottle feeding research, did not apply to breastfeeding. Why? The milk flow from bottles tends to be continuous and fast. In contrast, milk flow from the human breast can rapidly change, due to multiple milk ejections. The babies studied were able to quickly adjust to this with ""highly variable"" SSwB ratios ranging from 1:1:1 to 12:1:4. In fact, studies showed that babies were able to swallow while sucking, maintaining a constant flow of milk while continuing to take breaths.

However, when baby pauses to breathe while feeding from a conventional bottle, milk continues to flow into baby's mouth - disrupting a more natural SSwB ratio. With its continuous flow of milk, a conventional bottle does not encourage babies to learn to adapt and develop an active drinking pattern (as naturally occurs when breastfeeding).

Because of this lack of variation in flow, the researchers raised concerns about the negative aspects of bottle feeding, such as disorganized sucking, oxygen desaturation and forced SSwB patterns. One solution could be to design a bottle would that adapts to baby's own rhythm of feeding - so they can enjoy a calm, comfortable feed, and more easily switch between breast and bottle. 

References

1. Sakalidis VS, Geddes DT. Suck-Swallow-Breathe Dynamics in Breastfed Infants. J Hum Lact. 2016 May;32(2):201-11; quiz 393-5.