A Basic Guide to Deciding if I Need Birth Control After Chemo
Now let’s put everything together to help explain how birth control is recommended for people who have had chemo and don’t want to become pregnant.
Step 1:
What was your menopause status before chemo?
If you were already in menopause, you don’t need birth control
If you were still having periods, then keep reading.
Step 2:
What’s happening with your periods after chemo?
If you are still getting periods, even if they are lighter or irregular, you should use birth control.
Your doctor will check in with you about this over time – usually at least once a year.
If your periods have stopped completely, this is called chemo-caused amenorrhea.
Whether you still need birth control depends on how old you were when you got chemo:
- If you were younger than 40: Keep using birth control until at least age 45. Even if your period hasn’t come back, your ovaries might start working again later.
- If you were between 40 and 49 years old:
- If it’s been less than 2 years since your last period, use birth control. You could still ovulate (release an egg), which means pregnancy is still possible
- If it’s been 2 years or more since your last period, the chance of pregnancy is very low (less than 1%). You should talk with your doctor about whether you want to continue birth control. Your personal values and other health concerns matter too.
- If you were 50 or older: The chance of pregnancy is extremely low (less than 1%). It’s usually safe to stop birth control, but it’s still good to have a conversation with your doctor to make a decision together
If you are taking medicine to turn off your ovaries (like a GnRH agonist): these medicines make pregnancy very unlikely, so birth control is not typically recommended.
Does My Breast Cancer Type and Hormone Status Matter?
Understanding Birth Control Effectiveness
One of the most common questions people ask about birth control is:
“How well does this method actually work?”
The answer depends on the method and how you use it.
What is a failure rate?
Your healthcare team may talk about something called the failure rate, which is just another way of saying:
“Out of 100 people using this method for one year, how many are likely to get pregnant?”
Perfect Use vs. Typical Use
Every method has two effectiveness numbers:
Perfect use: When the method is used exactly right every single time
Typical use: How most people use a method in real life (missing pills, forgetting condoms, not using something every time, etc.)
Because real life isn’t perfect, typical use is usually less effective than perfect use.
Example: Withdrawal (“pulling out”)
Typical use: About 20 out of 100 people will get pregnant in a year
Perfect use: About 4 out of 100 people will get pregnant in a year
The difference shows how much everyday habits can affect effectiveness.
Comparing Methods to Using No Birth Control
It can be helpful to compare these numbers to not using any birth control at all.
Without any method, about 85 out of 100 people (85%) will get pregnant within one year.
Important note: This 85% number is based on studies of the general population, which often includes younger people with higher fertility.
For people who have had breast cancer, fertility may be lower because of age, treatments like chemotherapy, or other health factors. Still, pregnancy is possible, so birth control is important if avoiding pregnancy is the goal.
You can safely use hormone free methods, no matter what your breast cancer type, stage, or hormone receptor status (HR positive or HR negative). These are:
- The Copper IUD
- Fertility Awareness Methods (avoiding sex when you are fertile)
- Things you use or do at the time of sex
- Condoms, spermicides, vaginal gel, pull-out, and others
- Tubal surgery (female sterilization)
- Vasectomy (male sterilization)
Hormonal birth control methods are the most commonly used methods at the time people are diagnosed with breast cancer.
Many people may ask “What is my risk of breast cancer in the future if I use hormonal birth control after cancer treatment?”
Unfortunately, more studies need to be done to best answer this question for pre-menopausal patients with breast cancer.
BUT, based on the latest research and what we know about how the body works, we recommend the following…
If your top priority is avoiding a new or returning breast cancer over anything else (such as possible benefits of hormonal birth control), you should stay away from all hormonal birth control methods.
This includes hormonal methods that have both estrogen and progestin (a type of progesterone), as well as those that only have progestin – no matter what your hormone receptor is.
We know that for some people, under certain situations, the pros of hormonal birth control may outweigh the concerns about a new or returning breast cancer.
The decision to use hormonal birth control should be made on a case-by-case basis in discussion with the healthcare team prescribing your birth control and with your team of cancer specialists.
Emergency contraceptive (EC) pills are taken after sex (penis-in-the-vagina) to prevent pregnancy. These are also called “morning after” pills or a backup to regular birth control. EC pills are not abortion pills.
If you had sex without birth control, did not use your birth control as directed, or were forced to have sex less than 5 days ago, you can still use emergency contraception (EC) to prevent pregnancy.
Short-term use of EC pills does not raise the risk of breast cancer. EC pills are safe to use regardless of HR status.
There are two types of EC pills in the United States:
- Over the Counter (OTC) EC pills: OTC EC pills can be bought without a prescription at a pharmacy or online. Common brands include Plan B One-Step, Next Choice One Dose, Next Choice, and My Way. If taken correctly within 5 days after sex, OTC EC pills lower the risk of pregnancy by 70%. They work best if taken within 24 hours of sex. For people who weigh 154 lb (70 kg) or more, OTC EC pills may not be as effective.
- Prescription EC pill: This is a single pill called Ella. You need a prescription to get Ella. Ella works better than OTC EC pills. If taken within 5 days after sex, Ella lowers the risk of pregnancy by 85%. Ella is not affected by how much time has passed since sex- it works just as well on day 1 as on day 5. For people who weigh 194 lb (88 kg).
The Copper IUD can be used for emergency contraception, and it works a lot better than EC pills.