We usually think of regaining fertility after a baby as born as a one
way development-- We think that first there is amenorrhea when the baby
is young and nurses a lot and as the baby nurses less, fertility
(menses) returns.  This model is based on the way babies usually behave
in our culture ( progressively weaning with no backtracking allowed),
not on the mother's physiology.

        Among adoptive nursers, we see amenorrhea that occurs when the baby
gets "up to speed" in nursing.  In my experience, there seems to be some
kind of threshold of the total amount of time at breast, esp. at night,
and of milk produced that results in amenorrhea.  The threshold that
causes amenorrhea is different for different women.  Adoptive nursers
who produce little or no milk usually don't experience amenorrhea, even
if they nurse frequently. But many women do see their periods stop for
several months, just like women who are nursing children they gave birth
to. For vitually all adoptive nursers, this is secondary or induced
amenorrhea because they have had periods since the time of their last
pregnancy (if there was one.)  This phenomenon among adoptive nursers
shows that amenorrhea is a reaction to the baby's breastfeeding
behavior--not the mother's post partum status.

        The mother of the 9 mo old who is experiencing secondary amenorrhea
probably has a baby who has somehow changed his patterns enough to raise
her prolactin level again and thus suppress her estrogen levels.  As
many of us can attest, babies will frequently "backtrack" in their
breastfeeding behavior, if we follow their cues rather than our own
timelines. However, this mother could have a  sudden drop in prolactin
and possibly ovulate again at any time and, unless she wants to
conceive, she probably shouldn't rely on fertility signs for
contraception at this time.

How this explanation gives her a little piece of mind. A lot of women
freak out over missed/unusual periods and reassurance is an important
role for every health care provider!

Judy Gelman, IBCLC, LLL Leader
Washington, DC