Contraception Guidelines

Introduction to Combined Hormonal Contraceptives

Combined hormonal contraceptives in Canada typically contain ≤50 μg of ethinyl estradiol combined with a progestin, with daily doses of ethinyl estradiol ranging from 10-50 μg 1, 2
Estetrol, a newer natural estrogen, may have fewer adverse effects on blood pressure than ethinyl estradiol, according to the Society of Obstetricians and Gynaecologists of Canada 1

Progestins are classified into generations: first (norethindrone, ethynodiol diacetate), second (levonorgestrel, norgestrel), third (norgestimate, desogestrel), and fourth (drospirenone, dienogest) 1, 2
Fourth generation progestins, such as drospirenone, have anti-androgenic properties and may have beneficial effects on blood pressure 1, 2

Various formulations are available, including monophasic, multiphasic, cyclic, extended cyclic, and continuous, with different progestins such as norethindrone and drospirenone 1
Low dose monophasic OCPs containing 20-35 μg of ethinyl estradiol with a progestin have typical failure rates of 5-9% and are recommended by the American Academy of Pediatrics 3, 4
Efficacy can be compromised by missed pills, particularly when two or more consecutive pills are missed, and backup contraception should be used for 7 consecutive days 3, 4

Low dose OCPs are contraindicated in women with severe uncontrolled hypertension, complicated valvular heart disease, migraines with aura, active thromboembolism or thrombophilia, and complicated diabetes, as recommended by the Centers for Disease Control and Prevention 5
Low dose OCPs (≤35 μg ethinyl estradiol) increase VTE risk from baseline 1 per 10,000 to 3-4 per 10,000 woman-years, which is substantially lower than pregnancy-associated VTE risk (10-20 per 10,000 woman-years) 3, 5

Progestin-only contraceptives work primarily by thickening cervical mucus and require more stringent adherence than combined methods, providing an option for patients with contraindications to estrogen use 5
Levonorgestrel (Plan B) is available as a single 1.5 mg dose or two 0.75 mg doses 12 hours apart, while ulipristal acetate may be more effective than levonorgestrel at the end of the 5-day window and in women who weigh more than 165 pounds 5, 6
The American Academy of Pediatrics recommends levonorgestrel/ethinyl estradiol 30-35 μg and norgestimate/ethinyl estradiol 30-35 μg as starting options due to their well-established safety and efficacy profiles 3

If one pill is missed (<24 hours late), take immediately and continue regular schedule, while if two or more pills are missed (≥48 hours late), take the most recent missed pill immediately, continue regular schedule, use backup contraception for 7 consecutive days, and consider emergency contraception if unprotected intercourse occurred 3, 4
A follow-up visit 1-3 months after initiating OCPs is useful for addressing adverse effects or adherence issues, as recommended by the American Academy of Pediatrics, and the Centers for Disease Control and Prevention recommends prescribing up to 1 year of OCPs at a time 3, 5