Jan Barger asks what is the average age of weaning in the US.  I don't think
it is either possible or meaningful to come up with an average age of
weaning for the US.  Below is the section from chapter 4 of my new book,
where I talk specifically about this.  This follows a long section on the
supposed "average age of weaning for the world" being 4.2 as cited by Ruth
Lawrence (for which there are no supporting data).  Please do NOT pass this
on for consumption outside of LactNet.  Thanks.

"A U.S. average?  What would be the average age for cessation of
breastfeeding in the current United States?  In many parts of the country,
almost half of the children born are never put to the breast, thus their
"duration of breastfeeding" is zero.  Do we include them in our
calculations?  If so, the average duration of breastfeeding will be
extremely low.  If we limit our calculations only to those children who are
breastfed at least once, problems still abound.  In the extremely
breastfeeding-unfriendly culture of the United States, many hospital
policies and practices are inimical to breastfeeding--mothers are given
drugs during labor that cross the placenta and affect the baby's ability to
latch-on properly and coordinate their sucking and swallowing; mothers and
babies are routinely separated after birth, often for many hours; many
babies are given bottles of artificial infant formula, sugar water, and
pacifiers in the hospital nursery; mothers are advised to breastfeed on a
strict schedule, for a certain number of minutes per side; and mothers are
routinely sent home with free samples of artificial infant formula.  All of
these practices are known to interfere with the establishment of successful
breastfeeding.  Add to this the fact that many women have never seen anyone
breastfeed, have little support from family and friends, and have no access
to health care professionals who are knowledgeable about breastfeeding, and
it is not surprising that many women "give up" within the first few days or
weeks of their child's life.
        If it takes about six weeks for lactation to become well-established and
for mothers and children to settle into a successful breastfeeding
relationship, then perhaps we should not count in our "average duration"
calculations any children who are breastfed for less than six to eight
weeks.  Even where breastfeeding is going well, many women switch their
children over to formula in bottles when they return to work at six weeks
post-partum.  Are these children "weaned"?  Do we eliminate them?  If we
only count in our calculations children who are nursed beyond four weeks, to
capture those who were weaned when their mothers went back to work, then we
can perhaps say we have a fairly good idea of how long children are
routinely nursed at the breast in the United States.  But again, what would
this average age be, and what would it mean?  I suspect that a graph of the
distribution of age at cessation of breastfeeding for children in the United
States, counting only those who breastfed longer than four weeks, would be
heavily skewed to the right.  The peak (mode) would be less than 12 months,
the median only slightly higher than the mode, and the mean somewhat higher
still, due to the small but significant portion of children breastfed for
three, four, five, six, seven, eight, and even nine years of age.
        It is much more meaningful, for each clearly defined population, to report
the range and the shape of the distribution, rather than just the mean.  My
own research suggests that the "natural" duration of breastfeeding among
human, speaking biologically/physiologically, would be somewhere between 2.5
years and 7.0 years (discussed above).  At the same time, the cross-cultural
literature suggests that most children stop breastfeeding by  themselves
between three and five years if allowed to nurse as long as they want.  To
speak of a single, world-wide average age at cessation of breastfeeding
seems about as meaningful as speaking of a single world-wide average height,
or average age of menarche.  The 4.2 figure cited by Ruth Lawrence is
clearly not valid, regardless of how useful people have found it for
justifying extended breastfeeding.  The 2.8 year figure cited in my work
represents the median age (not the mean) for traditional societies prior to
the mid-20th century, not a current world-wide average."





Katherine A. Dettwyler, Ph.D.
Texas A&M University