Bleeding patterns with monophasic and triphasic low-dose ethinyl estradiol combined oral contraceptives

Background: This retrospective analysis evaluated the association of age and weight with cycle control in women using either of two formulations of low-estrogen-dose oral contraceptives. Study Design: Data for this secondary analysis were derived from a randomized multicenter trial assessing the efficacy and safety of norgestimate (NGM) 180/215/250 mcg/ethinyl estradiol (EE) 25 mcg (n=1506) and norethindrone acetate 1 mg/EE 20 mcg (n=1057). In this retrospective analysis, the incidence of breakthrough bleeding/spotting (BTB/S) was evaluated in women stratified by age (18-24, 25-34 and >34 years) and weight (<= 123, 124-155 and >155 lb). Results: A lower percentage of women experienced BTB/S with NGM/EE during most cycles, regardless of age or weight, compared with norethindrone acetate/EE. At Cycle 6, the incidences of BTB/S for NGM/EE versus norethindrone acetate/EE were as follows: 18-24 years, 10.9% versus 29.7% (p<.0001); 25-34 years, 10.9% versus 18.6% (p<.001); >34 years, 8.1% versus 19.1% (p<.005); <= 123 lb, 11.0% versus 25.4% (p<.0001); 124-155 lb, 10.0% versus 22.5% (p<.0001); and >155 lb, 10.0% versus 18.3% (p<.01). Conclusion: NGM/EE provided better cycle control as defined by BTB/S compared with norethindrone acetate/EE, regardless of subject age or weight for six cycles. (C) 2008 Elsevier Inc. All rights reserved.