Hormonal contraceptives such as birth control pills work by changing your usual menstrual cycle. The contraceptives contain synthetic versions of the female hormones that control the cycle. By maintaining the right levels of these hormones, they can prevent ovulation from happening so that there is no mature egg available to be fertilised. The hormones will also affect the womb lining, so it won’t go through the same cycle of thickening and then being shed during your period. However, you may still experience period-like bleeding when you are using birth control pills or other forms of hormonal contraception.
The Effects of Contraception on Your Menstrual Cycle
While all forms of hormonal contraception work in similar ways, there are some subtle differences in the way they affect your body. Different types of birth control pills and contraception can affect your menstrual cycle in different ways.
- Combined Pill: you will bleed on a very regular 28 day cycle when you are on the break between pill packets, but it may be lighter than your usual period.
- Progestogen Only Pill: there is no break between packets with the mini pill and its effects on your cycle can vary. Some women have regular periods, others have irregular ones, and some have none at all. Trying out the pill for a few months is the only way to know how it will affect you.
- Contraceptive Implants and Coils: most women will experience lighter bleeding or no bleeding at all, however some will have heavier periods with an implant. The Mirena coil is most likely to result in lighter, shorter or no periods. The copper coil or IUD is most likely to produce heavier bleeding.
- Contraceptive Injection: tends to result in irregular bleeding at first, but 50% of users will stop having periods after using the contraceptive injection for a year.