It is a simple blood test that can check hormone levels and is the best way to determine if entering perimenopause and menopause.
http://www.webmd.com/menopause/tc/me...xams-and-tests

If someone is on BC pills though, the tests can only be done during the placebo week and preferably at near the end of the week for the most accurate results. Also w/ BC pills, as long as you are on them you will continue to have periods. Studies have shown, that they can even put an 80 year old back on BC pills and she will have a period. So have to be careful that the BC pills can mask going into peri- and menopause. Talk with doc if notice any changes while on the pill to cycle, type of period or other symptoms for an indication; otherwise periodic blood tests may be the only way to tell.