i have had patients take other similar meds thruout pregnancy and baby was fine; however i was on adderall xr (similar but extended release instead of shorter acting like ritalin) last yr and continued to take it 2-4x/wk and my baby stopped growing and passed away at around 20 wks. he was very small for gestational age as was the placenta. i don't know if it was the med or not but i wouldn't go near it w a 10 ft pole while pg (as i am again expecting).
if you are nursing bc ritalin has a shorter acting half life you can time taking it w nursing sev hrs later when most of it is out of your system once nursing is on a more predictable schedule unlike the extended release add meds.
there are some good add sites specifically addressing women and meds during pregnancy and nursing but if i recall most of them just say there isn't a lot of data.
just my experience hth.
ok here are some references from the excellent book by sari solden "women w add": www.additudemag.com
look under medical center sectionwww.ncgiadd.org
(natl ctr for gender issues for add)www.addconsults.comwww.sarisolden.comwww.add.org