Brief Answer:
There are many benefits to extended cycles.

Detailed Answer:
When it comes to acne approximately all the current birth-control pills on the market are equally effective. This was established by a Cochrane review not too long ago. Despite marketing claims there is very little difference.
Patients on birth control pills, particularly extended cycles, will have far less breast breast tenderness. it may take several months to see benefit but continued benefits and increasing benefit will occur over the entire first year and even after she stops birth control pills benefits to the breast will continue.
Drospirinone containing birth control pills might be the best to prevent fluid retention; unfortunately because of mineralocorticoid activity they seem to be about the worst for avoiding breast tenderness.
Spotting and breakthrough bleeding can be a nuisance in the beginning few months of any birth control pill. The side effect diminishes overtime. The new Quadrphasic pills seem to have a small advantage and otherwise a 30 MGM ethinyl estradiol pill may have a small advantage over the 20 µg pills.
Extended cycle should decrease hormonal fluctuations and therefore she should have less irritability moodiness from withdrawal or from natural cycles. Despite claims that one is better, they all behaved pretty much equally.
So to sum up if avoiding breast pain is important use any birth control pill other than one containing Drospirinone . If breakthrough bleeding is likely to be the most important symptom to avoid then use a quadriphasic pill and simply skip the placebos. Finally she may benefit from a 30 MGM EE pill over a 20 MGM pill, at least in the beginning.
It is just how long she's willing to tolerate the lead time.
Any inexpensive generic 1/20 birth-control pill can be used simply skipping the placebo week three out of four packs. In terms of in terms of brand names of extended cycle pills prepackaged there are Seasonale Seasonique and the 20 MGM Seasonique Lo.
Up until modern times a woman's life expectancy was much shorter and without contraception she was either pregnant or breast-feeding most of the time having only a few natural cycles between those events. Relentless ovulation between menarche and menopause is an entirely modern phenomena and extended cycle seems more natural really then monthly menses. The only reason pills were originally conceived as three weeks on and one week off we should try to mimic a normal menstrual cycle and social convention. The inventor was a devout Catholic and hope the Catholic Church would approve this natural bleeding pattern. I hope your patient is happy with her extended use of birth control pills. It will take 3 to 6 months to establish her bleeding pattern. She will then have many satisfactory years. She is less likely to become amenorrhic on a 30 MGM EE pill, though many women do not mind having no cycle at all.

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