An editorial in the latest Canadian Medical Association Journal suggests to physicians that they don't disclose the sex of a fetus to its parents until after 30 weeks, when abortion of a healthy fetus is all but impossible, to avoid abortions motivated by the desire to have sons.
http://www.cmaj.ca/content/early/2012/01/16/cmaj.120021.full.pdf
A woman has a right to medical information about herself that is available to a health care professional to provide advice and treatment. The sex of the fetus is medically irrelevant information (except when managing rare, sex-linked illnesses) and does not affect care. Moreover, such information could in some instances facilitate female fetucide.
Medical colleges in Canada already discourage ultrasound for the sole purpose of sex determination. But it seems to me that an expectant woman has a right to this information if it is known, just as she has a right to all information discovered in a medical exam, whether or not the doctor decides it's "medically relevant."
OTOH, selectively terminating female fetuses because they are female is repugnant...