Most women will use some form of birth control at some point in their lives. Find out how different types of birth control affect your period.

Many forms of birth control use progestin and/or estrogen hormones to prevent ovulation and/or implantation. These hormones also affect the uterine lining, and can lead to some spotting in between periods, and they do reduce your menstrual bleeding.

How will my birth control affect my bleeding?

Birth control methods such as the pill, patch, vaginal ring, shot and IUD can all impact your menstrual bleeding. Some birth control methods can increase bleeding, and some can decrease it. Many aspects of bleeding can be affected, and these effects can change over time. Periods can be longer, shorter, heavier, or lighter, depending on the method of birth control. Spotting and irregular bleeding are common side effects of most methods of hormonal birth control, especially in the first few months of use.

Birth control pills

Birth control pills were originally only packaged as 28 pills – 21 pills containing the hormone(s) required to suppress ovulation, and 7 placebo pills (no active ingredients). The 7 days of placebo were designed to allow menstruation to occur. Today there are a variety of regimens available, such as 24 days of active-ingredient pills and 4 days of placebo, and extended-cycle regimens that can be taken for up to a year to stop all menstrual bleeding.

No matter which birth control pill you are taking, you may experience irregular spotting or bleeding during the first few months of taking the birth control pill. This is more common when you are taking progestin-only pills (the ‘mini-pill’), compared to combination pills that contain estrogen and progestin. It is also more common to have spotting when taking a ‘monophasic’ pill (same dose of hormones every day), compared to a ‘triphasic’ pill (different dosages over the cycle). Spotting can also result from forgetting to take a pill, or taking it late. Taking your pill even a few hours later than normal can cause spotting, especially with the progestin-only pill.

Injected and implanted contraceptives

Irregular, unpredictable bleeding is very common in women using long-acting, progestin-based birth control methods (e.g., Depo Provera®, Implanon®). After a year of use, about half of women will have no periods.

Intrauterine devices

There are two types of IUDs available, the copper IUD and the progestin IUD. With the copper IUD, spotting between periods and heavier, longer, and more painful periods are common in the first three to six months. Most women find this improves over time, and normal or near-normal periods resume after a few months.

With a progestin IUD, spotting between periods and irregular periods are common in the first three to six months. Usually this improves over time and many women ultimately have light or absent periods with the progestin IUD. The progestin IUD can be effective for many years (a new one is reinserted after 5 years). A smaller mini-IUD is also available, and may be preferable for women who have not had a child.

Vaginal ring

This small, flexible ring is inserted high in the vagina, and releases estrogen and progestin, which prevent ovulation. The vaginal ring is usually left in for three weeks, and then removed for a week to allow menstruation to occur but it can be used continuously or in an extended fashion with a new ring every month. Spotting between periods may happen, particularly in the first three months.

Emergency contraceptives

The ‘morning after’ pill may affect the length of your menstrual cycle, causing your period to come earlier or later than you were expecting it to. If you take emergency contraceptive pills in the first three weeks of your cycle, your period is likely to come early. Your period may also last longer than normal. In most cases, the earlier you are in your cycle, the sooner your period will come. If you took emergency contraception in the later part of your cycle (after ovulation), your period may be delayed. Some women also experience spotting between periods after taking emergency contraception. Your next menstrual cycle may also be slightly longer than normal, but if your next period is more than a couple of days late, it is a good idea to use a pregnancy test.

Emergency contraception is not to be used as a regular method of birth control but, if needed, it can help prevent unplanned pregnancies.

When should I see my doctor about irregular bleeding?

Since every woman’s body reacts differently to these birth control methods, it can be hard to know when irregular bleeding is abnormal.  You should see your doctor if you experience abnormal bleeding:

• And are pregnant
• And have a lot of pain during your period
• After intercourse
• And you have been using the same method of birth control for more than three months
• That is unexpected
• And you are younger than 8 years old or have no other signs of puberty and have vaginal bleeding

You should also see your doctor if you are taking a combined contraceptive pill and your periods have stopped completely during the week of placebo pills, although in many cases this can be normal.

There are treatments available for irregular bleeding (e.g., ibuprofen, supplemental estrogen) that can help, or your doctor may recommend changes to your birth control method.

Side effects of hormonal birth control

You may experience side effects when using any type of hormonal birth control. These vary a little depending on which type of birth control you are using. Tell your doctor about any side effects that are bothering you.

Although it is rare, hormonal birth control methods, especially those that contain estrogen, increase your risk of developing a blood clot in your leg (deep vein thrombosis). Seek medical help immediately if you have trouble breathing, which can happen if a clot moves into your lung (pulmonary embolism). A pulmonary embolism is a medical emergency.

For more information on contraception options, including their advantages and disadvantages, click here.