"I need a refill for my birth control pill, but I'm wondering if I should switch to one of the newer pills that I've seen advertised." I hear this daily, and my advice on pill switching is simple: if it's not broken, don't fix it. If you've found a pill that works with your body, and you've got predictable short periods and no side effects, there's no need to trade in your pill for a newer, shinier model. All pills are about the same in effectiveness and risks, and there's no reason for most women to switch.

On the other hand, if you're unhappy with your current pill, there are multiple new pills now available that are markedly different from the old ones. If you're thinking of starting the pill for the first time, or restarting after a break, they offer some new choices. Traditionally, pills come in what we call 21/7 formulations: 21 days of hormones, followed by 7 days of placebos. These lead to predictable bleeding (a "withdrawal bleed," as in withdrawal from hormones) once a month. The new pills come in three different formulations:

• 24/4 pills. Two brands: YAZ and LoEstrin-24. These pills have a shorter placebo week, and many women have shorter periods of bleeding (but not everyone). They also give you a cushion of safety if you begin a pack late (not that you ever need it, right?)--your risk of pregnancy is lower if you don't miss hormones for more than seven days. Bleeding: once a month.

• 84/7* pills. Two brands: Seasonale and Seasonique. These pills have almost 3 consecutive months of hormones before the placebo week (Seasonale) or a week of a tiny daily bit of hormones (Seasonique). Breakthrough bleeding or spotting is normal and common at first, as your body becomes accustomed to the new routine. Bleeding (after adjustment): 4 times a year.

• "365" pills. One brand: Lybrel. With Lybrel, you take hormone pills every day--no placebo pills at all. It can take up to a year for your periods to disappear, and your bleeding may be irregular until then. Bleeding (after adjustment, for most women): never. 

These pills may be especially good for women with heinous hormone-withdrawal symptoms, like killer migraines--fewer placebo days, fewer symptoms. Have any of you tried any of these newer pills? What did you think?