Nanda: The standard way to take combined contraceptives is cyclically, every day for three weeks, and then you have a break in the hormones for a week. You either don’t take a pill, or you take a placebo for a week, so you have what’s called a withdrawal bleed. The lining of the uterus sheds, and that’s what people call a “period,” although it’s really just a hormone-free withdrawal bleed. But when we talk about continuous use, you don’t take any breaks. The uterine lining stays thin and intact, and this means that users can go weeks, months or even longer, without a “period.”
CNN: How long can you safely go without a monthly bleed?
Nanda: There have been studies comparing continuous versus cyclical use, and it’s just as effective and just as safe. There’s no medical reason to have a period or withdrawal bleed when you’re on hormonal contraceptives. As long as you don’t have any contraindications (medical conditions) for the birth control pill, you don’t have contraindications for the continuous use of the pill.
Historically, before contraception, women didn’t necessarily bleed all the time, because a lot of time was spent either being pregnant or breastfeeding. In both of those conditions, there’s no monthly bleeding, often for months.
Now, if you’re not pregnant or breastfeeding, you’re not on hormonal contraception, and you don’t have a monthly period — that’s something you do need to discuss with your provider, because that could signal an issue.
CNN: Are there any side effects specific to continuous use?
Nanda: The side effects in general are similar to those with cyclical use. For example, you might have nausea, breast tenderness and headaches (at any time). With continuous use, some people experience unexpected breakthrough bleeding or spotting, especially initially, but this usually improves over time, and many people do achieve amenorrhea or (the) cessation of menses. For some people, it may take three to four months.
CNN: How does continuous use affect fertility after stopping?
Nanda: There’s no evidence that long-term use of hormonal contraception — whether it’s combined hormonal interception, taken continuously or cyclically — causes infertility, and fertility typically returns within a month or two. Basically, once you stop, the (synthetic) hormones go away very quickly from the blood, ovulation is no longer suppressed, your normal estrogen and progesterone production resume. Assuming that you had normal menstrual cycles before, they would resume. (One exception is) if you’re taking something like the Depo Provera contraceptive injection. It doesn’t cause infertility, but it may take longer for fertility to return after injections.
CNN: Why were placebo pills invented if there’s no harm in skipping them?
Nanda: When the combined oral contraceptive pill was developed in the 1950s, the now-standard 21 days of active pills followed by a seven-day hormone-free interval was not based on medical necessity, but rather on cultural and strategic reasons. At the time, there was a widely held belief that menstruating every 28 days was a sign of normal female reproductive function.
To align with that expectation, the regimen was designed to mimic a natural menstrual cycle, with a monthly withdrawal bleed intended to reassure both users and physicians that they were not pregnant — important in an era before home pregnancy tests were readily available — and, at the time, to help ease religious and societal resistance to contraception.