Does starting a hormonal birth control method at a patient's initial visit, regardless of the patient's day of the menstrual cycle, decrease undesired pregnancy, improve continuation of the method, or change the adverse-effect profile when compared with the standard menses-dependent approach?
Giving an injection of medroxyprogesterone (Depo-Provera) on any day of a patient's menstrual cycle decreases unintended pregnancies. For other hormonal methods, there is limited evidence. Compared with deferring until the patient's next menses, immediate start of hormonal methods appears to produce similar adverse effects. There is inconsistent evidence that the immediate-start approach improves continuation rates.
There are several reasons why physicians may delay starting a hormonal contraceptive method: concerns about adverse effects from interruption of the menstrual cycle; fear of teratogenic effects of hormones on early, undetected pregnancy; and fear of delayed diagnosis of pregnancy. In this Cochrane review, the authors found five randomized controlled trials of immediate start versus conventional start of hormonal birth control (n = 2,427). They found that bleeding patterns and adverse effects were similar in patients who started contraception immediately compared with conventional start. Regarding teratogenicity, there is evidence that exposure to oral contraceptives early in pregnancy is not harmful to the growing fetus.1 There is little evidence that pregnancy rates are significantly affected, except when using medroxyprogesterone injection. In this review, immediate start of medroxyprogesterone injection decreased unintended pregnancies when the method began on the day of the office visit (odds ratio = 0.36; 95% confidence interval, 0.16 to 0.84).
Physicians who want to prescribe oral birth control using the immediate-start method should adhere to a few basic principles. The evaluation should begin with a negative pregnancy test in the office. After counseling, if the patient desires a non-implantable hormonal contraceptive, the method can be started any day of the menstrual cycle. A back-up barrier method, such as a condom, is recommended for seven days for women who are not in the first five days of their cycle. If the patient is beyond the first five days of her menstrual cycle and has had unprotected intercourse within the past five days, the physician should offer counseling about the possibility of an early pregnancy, and an emergency contraceptive should also be offered if the patient still desires an immediate start. Follow-up urine pregnancy testing is recommended after two weeks to confirm that the patient is not pregnant.2