Lois:  You raise a good question which I'm sure no one has the answer
to.  You're probably correct that HIV transmission to babies from
mother's sexual contact with a partner engaging in risky behaviors is
very rare.  The only documented cases were from blood transfusions, which
presumably give a much higher viral load.  However, we must assume that
there is some, even if very slight risk.
That leaves us with a dilemma in counselling.  My approach is to work on
early prenatal education of every mother, advising her that risk
behaviors during lactation lead not only to a risk of infecting her but
also possibly her baby.  That hopefully would deter many from engaging in
known high-risk behaviors themselves.  However, I strongly believe in
counselling fathers prenatally and encourage them to attend prenatal
classes.  This would be an ideal time to educate fathers about the
possibility that risk behavior on their parts not only puts their partner
at risk of HIV but possibly also the baby.  It's naive to expect that all
fathers who would have engaged in risky behaviors would now refrain on
the basis of this information, but hopefully most of them would.
Alicia.  [log in to unmask]