The ultrasound studies of nipples in mouths of nursing babies suggest that
the nipple is compressed to about half its resting diameter in order to
elicit maximum milk ejection.  When mothers have very large diameter nipples
(which can happen unilaterally or bi-laterally) the baby can be very
challenged to thin it sufficiently during nursing.  Such babies may perch
out on the nipple shaft just coasting on the mom's letdown, or they may chew
and injur the tissue.  If baby can't empty the breast as the result of
inability to really milk that 'teat' then hand expression or a pump must be
used to protect the milk supply.  If a pump is used, you have to visualize
the fit between the nipple and the pump flange or you strangle the milk
flow.  The only published study I have found that mentions nipple diameter
suggests that about 17 mm is average. (Zeimer's sore nipple study back in
1993).  That looks about right to me.  That's the size of an American dime
(or an Australian or NZ 5 cent piece).  If you have nipples the diameter of
an American quarter (Aust. or NZ 1 dollar coin) then you need a larger pump
flange to accommodate the nipple.  Some of the cracks at the base of the
nipples may be caused by abrasion from too-tight pump flanges.

Barbara Wilson-Clay BSEd, IBCLC
Austin Lactation Associates
http://www.lactnews.com

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