Dear LactNetters -- I too was dismayed that Natural History chose to publish
Rose Frisch's letter.  They had sent me a copy of it, and I did respond
privately to her.  I declined the chance to comment in the letters section
of Natural History because I said there was no way I could rebut what she
said in one short paragraph without references.  I also suggested they not
publish it because it would be embarressing to her to be shown publicly to
be so out of touch with current research (the studies she alludes to were
done in the 1960s), and because I had the greatest respect for her body of
work and didn't want her to be embarressed this way.

Dr. Rose Frisch is an anthropologist, now retired, who did some very
important work in the 1970s establishing that weight/percent body fat were
directly related to fertility through both primary amenorrhea (not having
your menstrual periods begin until later than girls who had more body fat)
and secondary amenorrhea (not having your menstrual periods for a while
after you had already begun menstruating because your body fat levels got
too low -- such as athletes, anorexic women, and severely malnourished women).

There is quite a bit of evidence that women who are malnourished have longer
lactational amenorrhea that women who are better nourished, all other things
being equal.  There is even some evidence to suggest that prolactin surges
from the baby latching on are greater in malnourished women.  Current
thinking is that it is not prolactin per se that suppresses ovulation, but
something that covaries with prolactin.  None-the-less, it does seem clear
that nutritional status *is* directly related to duration of lactational
amenorrhea.  A large portion of the variation between individual women in
experience of lactational amenorrhea remains unexplained.  There are some
malnourished women whose menstrual periods return early even if they do
everything "right."  There are some very well nourished women who nurse in a
physiological pattern of at least once every hour during the day and several
times at night, who experience 1-3 years of lactational amenorrhea.  Thus,
while Dr. Frisch is incorrect to label the link between breastfeeding and
fertility a "myth," she is correct that nutritional status plays some role,
and that we still have a long way to go before we understand all the factors
that affect post-partum fertility.

The very best recent summary of the research on the link between
breastfeeding and suppression of fertility is Peter Ellison's chapter in
Breastfeeding: Biocultural Perspectives (1995).  The more recent work trying
to figure out exactly what the mechanism is, if not prolactin, is by
McNeilly and colleagues.

If anyone knows Dr. Labbok, and could ask her to send copies of her
publications to Dr. Frisch, that would be useful.  Other letters to Natural
History would also be nice.  It especially riles me that they printed this
letter, because my original piece said nothing about contraception, but was
simply about my own research on age at weaning.  The editor at Natural
History insisted I work something in about the contraceptive/child-spacing
effect of breastfeeding, even though I said it was too complicated to
explain in a sentence or two.  So I feel I've been criticized for something
I didn't really say.

Whining in Texas . . . .

Kathy Dettwyler