Increased Risk of Breakthrough Bleeding When One Oral-Contraceptive Tablet Is Missed

Abstract

To the Editor: Breakthrough bleeding is quite common among users of oral contraceptives and is a frequent reason for discontinuing this method. The incidence of this side effect, however, varies from one study to another. Some of this variation may relate to how regularly the contraceptive tablet is ingested in different study populations. In a double-blind crossover study (480 cases) on the differential effects of three oral contraceptives — Ovral (ethinyl estradiol, 0.05 mg, and norgestrel, 0.5 mg), Norinyl (mestranol, 0.05 mg and norethindrone, 1.0 mg) and Norlestrin (ethinyl estradiol, 0.05 mg, and norethindrone acetate, 1.0 mg) — carried . . .