What’s inside the pill?
There are two main types of contraceptive pills: combined oral contraceptives (COCs) and so-called progestogen-only pills, or POPs (these also used to be called minipills). Both types contain synthetic analogs of female sex hormones. COCs have both synthetic estrogens and synthetic forms of progesterone (progestogens), while the POPs contain progestogens alone.
Female sex hormones influence the body at different levels. That’s why, apart from preventing unintended pregnancy, birth control pills can treat hormonal imbalance or mitigate symptoms related to the menstrual cycle.
Strictly speaking, if you are taking hormonal contraceptives, you don’t have periods. Instead, there are two different kinds of period-like bleeding that can happen.
Withdrawal bleeding is common among those who use COCs. It occurs when you take a scheduled break, stop taking pills at all, or take placebo pills for 7 days. This type of bleeding is easiest to control. It’s called withdrawal bleeding because it is induced by the withdrawal of the hormones during the break.
The other form of bleeding is called breakthrough bleeding. The name comes from the fact that the bleeding occurs while taking the pill. It happens when the inner lining of the uterus does not get enough hormones to remain stable and starts bleeding.
However, it’s not a sign of anything going wrong — just a sign that the inner lining has to adapt to the hormones.
Breakthrough bleeding is more typical for POP users because it is taken continuously without a break. It’s irregular by nature, which is why POPs are not the best choice if you want to be in control of your bleeding. Breakthrough bleeding may also occur if you miss a COC pill.
If you are having irregular periods, your doctor may prescribe you COCs to treat this condition. By releasing the right amounts of the right hormones at the right times into your bloodstream, these pills create a “hormonal contraceptive cycle” in your body. This is similar to a natural menstrual cycle, but it can be much more regular and predictable for some people.
From a medical point of view, it’s not necessary to have withdrawal bleeding every 28 days, as many contraceptive regimens suggest. In fact, it’s possible to take COCs every day with a short break every 3 months or even less often. People who do this have breakthrough period-like bleeding 4 times a year or less, on schedule.