Oral contraceptives are powerful and effective drugs which can cause side effects in some users and should not be used at all by some women. The most serious known side effect is blood clotting, which can be fatal." -- from the label on packages sold in the U.S. of Ovulen, a birth control pill made by G. D. Searle Co.
"No significant increase has been observed in incidence of thrombophlebitis [blood clotting] or any of its complications in women taking oral contraceptives. -- from a promotional booklet about Ovulen distributed by G. D. Searle Co. in Colombia.