Thank you to everyone who responded to my question, wondering about the
possible impact of breastfeeding on early pregnancy after successful
implantation of a fertilized egg (a clinically detectable pregnancy).

I'm still trying to wrap my mind around the mechanism by which breastfeeding
decreases progesterone once a woman's menstrual cycles have resumed.

According to Adventures in Tandem Nursing (Flower, 2003):

"Most breastfeeding women who are experiencing menstrual cycles are back to
their normal level of fertility.  In a minority of women who are
menstruating, breastfeeding continues to hold back luteal functioning for
one or more cycles, creating a temporary breastfeeding-induced "luteal phase
defect" (usually related to inadequate functioning of the corpus luteum in
the ovary, responsible for producing hormones that prepare the uterus for
implantation).  [charting can provide information about the length of a
woman's luteal phase]

If luteal functioning is sufficient for implantation to be successful, there
is no indication that breastfeeding can have any negative impact, according
to miscarriage expert Lesley Regan, PhD, MD.  This is also the observation
of prominent researcher of breastfeeding and fertility Alan McNeilly, PhD,
Professor and Deputy Director of the Medical Research Council's Human
Reproductive Sciences Unit in Edinburg, Scotland.

So the bottom line is simple:  If your pregnancy can be clinically
recognized, implantation has been successful, and breastfeeding is unlikely
to interfere with the pregnancy."

Ingrid Tilstra, LLLL, IBCLC

             ***********************************************

Archives: http://community.lsoft.com/archives/LACTNET.html
To reach list owners: [log in to unmask]
Mail all list management commands to: [log in to unmask]
COMMANDS:
1. To temporarily stop your subscription write in the body of an email: set lactnet nomail
2. To start it again: set lactnet mail
3. To unsubscribe: unsubscribe lactnet
4. To get a comprehensive list of rules and directions: get lactnet welcome