A number of medical studies now indicate that maternal smoking during
pregnancy can permanently affect brain development, inhibiting the growth of
neurons.  Nicotine may also alter alter the brain biochemistry by altering DNA
and RNA synthesis.  Children of mother who smoke during pregnancy have higher
rates of neurobiological difficulties, including inattention, impulsivity, and
hyperactivity.  I would surmise that smoking during breastfeeding would
continue the nicotine exposure and might contribute to some of these
biochemical changes.  (Although the other benefits of breastfeeding might
offset some of these negatives significantly.)

Smoking in the household has been shown in a large number of studies to be
associated with markedly increased rates (6-10 times increased) of wheezing,
asthma development, otitis media, bronchiolitis, chronic bronchitis, and URI's
in children exposed to smoke; the effects are dose-dependent.  It takes about
2 weeks to completely clear secondhand smoke from a room once it's been smoked
in.  Therefore, parents (and other relatives/friends/etc.) who are nicotine
addicts (and nicotine IS an addictive drug) should smoke outside.

Maybe some of this information can be used to help convince nicotine-addicted
moms (and dads) that their smoking is very harmful to their baby and help them
decide to quit (or at least smoke outside).

It is still better for the infant to be breastfed by a smoking mom than not to
be breastfed at all, however, since an artificially-fed infant has even more
health risks.

Linda L. Shaw MD FAAP