This is an auto immune disease of the thyroid.  It can give no symptoms,
or symptoms of hyper or hypo thyroidism.  The symptoms may begin as
hyper and then go to either no or hypothyroid symptoms.  Often mothers
do end up with hypothyroidism.

Hypothyroidism *may* cause decreased supply problems, probably because
the whole body slows down (Thyroid Stimulating Hormone, which is
elevated in thyroid underactivity actually has prolactin like effects on
the breast, but may not overcome the decreased milk supply).
Hyperthyroidism *may* cause decreased milk supply also, but I am not
sure why.  In fact, most women with thyroid problems, have *not* had
problems with supply, in my experience.

A good start will prevent most problems.

Jack Newman, MD, FRCPC