Latching and sucking

What happens to my nipple in the baby’s mouth?

Babies get milk by latching onto the nipple and nipple root and sucking. They use the tongue, cheek muscles, and roof of the mouth to create a chamber and generate suction. When the lower jaw and tongue move down, suction increases which pulls milk from the breast. As the jaw and tongue move upward, the milk moves back in the mouth and is swallowed. Some babies are unable to latch or suck effectively leading to hunger and poor growth.

A) Describing latching and sucking

Latching refers to the baby holding the nipple and tissues just behind the nipple (the nipple root) in the mouth. To latch, babies need to create a minimum amount of suction to keep these structures in the right place in the mouth. 

How well a baby latches depends on:

  • The baby's abilities.
  • The baby's positioning.
  • The mother's nipple root characteristics.
  • The mother's latching technique

There are number of signs that a baby is properly latched.
Sucking refers to the baby’s tongue and lower jaw moving down to temporarily increase the amount of vacuum to extract milk. As it moves back up, the tongue will move the milk towards the throat, where it is swallowed (Elad 2014; Geddes 2008). Sucking also stimulates the breast to create a let-down which brings milk forward in the breast to the nipple.

In order to keep liquids from entering the breathing tube (trachea), babies do not breathe when swallowing. This requires coordination and can be difficult for some premature babies.

B) The process of latching and sucking

1) Supporting the baby

Younger babies may be able to latch themselves but others may need significant help.

Older babies generally only need to be positioned in front of the nipple and will latch themselves. With time, they will even position themselves. Older babies will also not open their mouths as wide when latching.

2) The position of the nipple and nipple root in the baby’s mouth

Researchers have used ultrasound imaging to see what happens to the nipple and the nipple root when the baby breastfeeds (Geddes 2017).

Babies use the tongue, cheek muscles, and roof of the mouth (palate) to create a chamber where suction is produced by the tongue dropping. The suction in the baby’s mouth holds the nipple and nipple root in the mouth. These two together form a unit: a teat.

The nipple face is held close to the area where the palate changes from hard to soft (the junction of the hard and soft palate). You can feel this area in your own mouth by pushing your tongue against the roof of your mouth. The junction is about two-thirds of the way towards your throat.

During breastfeeding, the tip of the tongue covers the lower gum and extends a little further out.

3) The process of sucking 

As the baby’s lower jaw drops, the front and middle of the tongue drop as well, increasing the suction and creating a space for milk (Elad 2014). Maximum suction strength has been reported to be -145 ± 58 mmHg (Geddes 2008) and -197 ± 10 (Prieto 1996). 

As the jaw and tongue move upward, the suction strength decreases. This baseline suction strength has been reported to be −64 ±45 mmHg (Geddes 2008). At the same time, the milk moves back in the mouth and is swallowed. The baby briefly stops breathing when swallowing.

Babies suck at a rate of 90 times per minute (Elad 2014; Prieto 1996; Sakalidis 2013). Babies will suck with very few pauses at the start of breastfeeding and gradually increase the number and length of pauses as breastfeeding continues. The relationship between sucking and pausing can be divided into three stages.

C) Latching and sucking problems

Barriers to latching and sucking can arise both with the baby or the mother, resulting in ineffective breastfeeding.

1) The baby’s situation

Some babies are unable to latch for a variety of reasons and will be underfed if the problem is not addressed. For example, premature babies often have weak suction strength or may have trouble coordinating sucking and swallowing. Occasionally tongue-ties can affect sucking.  

2) The mother’s situation

Mothers with a firm nipple root or inverted nipples are more likely to have difficulty latching their babies and are more prone to painful and damaged nipples.

 Poor positioning can make these problems even worse.

On rare occasions mothers with large nipples can have difficulty latching very small babies.


Elad D, Kozlovsky P, Blum O, et al. Biomechanics of milk extraction during breast-feeding. Proc Natl Acad Sci U S A. 2014 Apr 8;111(14):5230-5
Geddes DT, Chooi K, Nancarrow K, et al. Characterisation of sucking dynamics of breastfeeding preterm infants: a cross sectional study. BMC Pregnancy Childbirth. 2017 Nov 17;17(1):386
Geddes DT, Langton DB, Gollow I, et al. Frenulotomy for breastfeeding infants with ankyloglossia: effect on milk removal and sucking mechanism as imaged by ultrasound. Pediatrics. 2008 Jul;122(1):e188-94

Prieto CR, Cardenas H, Salvatierra AM, et al. Sucking pressure and its relationship to milk transfer during breastfeeding in humans. J Reprod Fertil. 1996 Sep;108(1):69-74

Sakalidis VS, Williams TM, Garbin CP, et al. Ultrasound imaging of infant sucking dynamics during the establishment of lactation. J Hum Lact. 2013 May;29(2):205-13