Contraception and your cycle
Not all contraceptives are the same. Different methods take effect during different phases of your menstrual cycle. As a result, some methods can cause a change in the menstrual cycle whilst others will not.
If you experience heavy or prolonged bleeding, or if you have any other concerns, you should consult your doctor.
The combined oral contraceptive pill and the monthly ring contain two types of hormones – oestrogen and progestogen – whereas the minipill, the 3-yearly implant and 5-yearly IUS contain just progestogen.
For women using the combined pill or the monthly ring, the lining of the uterus builds up similar to, but thinner than during a normal menstrual cycle. This lining is generally stable and begins to break down once the source of the hormones is stopped; i.e. you begin taking the inactive pills, or the ring is removed.
When you are using a progestogen-only contraceptive, the continuous exposure to the hormone progestogen will prevent the usual cycle of thickening and shedding of the lining of the uterus. The constant progestogen dose causes the lining to be a lot thinner than it is during a menstrual cycle or when taking the combined pill. For some, this thin lining is quite stable and there is little or no bleeding. In others the lining is fragile and bleeding may be frequent and unpredictable.
There are two forms of the oral contraceptive pill.
The combined oral contraceptive pill contains two hormones; progesterone and oestrogen. It is taken every day, at roughly the same time, for three weeks followed by a week’s break during which you may take inactive sugar tablets or no tablets at all.
Within a few days of stopping the combined pill, the lining is no longer held by the hormones and breaks down. You should experience a bleed similar to but lighter than a normal period. Bleeding should only occur when the hormones are NOT being taken.
The minipill contains small amounts of one hormone called progestogen. It is taken regularly at the same time each day without a break. The minipill causes a change in bleeding patterns. Some women may experience irregular or unpredictable bleeding patterns.
The monthly ring releases a continuous low dose of oestrogen and progesterone, which prevent ovulation.
The ring is removed after 3 weeks and withdrawal bleeding, which is similar to that which occurs with the combined contraceptive pill, will occur in the 4th week.
The three-yearly implant is a small plastic rod that is placed under the skin of the upper arm, and slowly releases progestogen into the blood stream. It works by stopping the ovaries releasing an egg each month.
The implant causes a change in bleeding patterns. Some women have no bleeding at all, while others may experience infrequent, frequent or prolonged bleeding. Generally the type of bleeding pattern experienced in the first 3 months predicts the ongoing bleeding pattern.
The five-yearly intrauterine system (IUS) is a small plastic device that is placed in the uterus and slowly releases progestogen directly into the uterus.
The IUS works in a number of ways; by preventing sperm from fertilising an egg by stopping the sperm from getting into the uterus; and also, by preventing a fertilised egg from implanting in the uterus.
The IUS can have an effect on your regular bleeding patterns. Unpredictable bleeding and spotting is common in the first few months. Periods usually become light, or stop after about a year.
The contraceptive injection is a progestogen-only intramuscular injection. It works by inhibiting ovulation, as well as preventing sperm from reaching the egg.
The contraceptive injection is a long-acting method of contraception, and cannot be reversed once administered. Initially it can have an unpredictable effect on your regular bleeding patterns. Long term use may cause your periods to stop, which may be a desired outcome.