Regarding the combined oral contraceptive pill, I agree with Jack that it
is not advisable in the first 12 months or so. But I think after 12 months,
it is possible to use it -  the oestrogen is less likely to lower supply at
that time, (I've seen women going on the pill as a means of weaning -
unsuccessfully!).  And the baby is eating other foods, so the baby's intake
of oestrogen is not likely to be a problem. If you think about it, when a
lactating woman is pregnant she is going to have higher levels of oestrogen
circulating than a woman on the O.C.
Lisa Amir
GP / IBCLC in Melbourne, Australia, sunny and 25 C today :)