I spent most of my day trying to run down the reference (I know it is out
there!) - but no luck - so, am stuck with personal experience only. During both
breastfeeding relationships I have a cyclic decrease in my milk supply that
builds prior to menstruation, with an abundance of milk on day two or three
after my period begins. This cycling of my supply is subtle - the toddler is
more whinny, asking to nurse more frequently as the days go by, more frequently
I'm awakened with a sleeping toddler attached at night, that sort of thing. The
baby doesn't suffer for volume, they just spend more time at the breast until
satisfied. I notice this volume change when my menstrual cycles begin to
reestablish themselves. And I'm sure I read about this - possibly in a toddler
breastfeeding piece that doesn't come to mind to check.

Could this mother be pregnant?

The flip side of the coin is that this mother's periods may have returned
because something else is interfering with the breastmilk transfer/suckling,
causing a shift in her hormone levels. The age old problem: which came first the
chicken or the egg?

Jill, I feel like I'm committing heresey in saying this, but here goes. At some
point in a consultation when the focus on exclusivity jepordizes the
breastfeeding relationship, the mother may need your help in recognizing that
she IS STILL a breastfeeding mother even though a supplement is needed to get
through the day. In fact I consider a mother in a  breastfeeding relationship
even when NO breastmilk is tranferred (i.e. inducing or relactating). This is
not a commonly held concept in our world. We (collectively as a society) think
very little of the intimate relationship nuturing the infant's growth and
development, and tend to concentrate on the value of the breastmilk fluid alone.
Sometimes mothers need this perspective.