Do I Need Birth Control?
How the Ovaries Work and How They Change Over Time
At birth, the ovaries hold all the eggs that a person has for life. No new eggs are made.
During the reproductive years, the ovaries release an egg about once a month.
The ovaries also make hormones that control periods, including estrogen and progesterone.
Over time, the ovaries make lower amounts of hormones and release fewer eggs. The time when these changes begin is called perimenopause. During perimenopause, periods may become less regular. Pregnancy is less likely, but it can still happen.
Menopause happens when the ovaries stop working. They no longer release eggs or make hormones. Periods stop completely. Fertility has ended. After menopause, there is no need to use birth control to prevent pregnancy.
How Does Chemotherapy Affect the Ovaries?
Chemotherapy can damage some or all of the eggs in your ovaries.
Two important things can happen from this damage:
1. Periods can become irregular or even stop.
2. The ovaries stop releasing eggs making it hard to get pregnant.
But, these two events are not always linked. That is, one can happen without the other.
This means you CANNOT rely on your periods to figure out if you are at risk for pregnancy and need birth control.
Even if you do not have your period, you can still get pregnant [callout box to highlight as well]
For example, even if your periods have stopped, your ovaries may still be releasing eggs and you could get pregnant.
The opposite can happen too. Your periods may look and feel normal, yet your ovaries are not releasing eggs and it will be hard to get pregnant.
There is a lot of confusion about whether pregnancy is possible after chemotherapy.
Even though chemotherapy can damage your eggs, it is still possible to get pregnant during or after chemotherapy. It will depend on how much damage was done to the ovaries.
If chemotherapy harms some but not all eggs, there can be a temporary “pause” in your fertility. However, there are healthy eggs left that can be released weeks, months, or sometimes years later. If you do not want to get pregnant, birth control should be used this whole time.
If chemotherapy harms all eggs, there is permanent loss of fertility. This means that the chemotherapy has caused menopause. There is no need for birth control to prevent pregnancy after menopause.
BUT: Early after chemo, there is no perfect way to tell which one you are experiencing.
Why this matters for birth control:
You can still get pregnant during temporary “quiet periods.” Because cycles are not reliable, birth control is recommended until menopause is clearly confirmed.
Is it Menopause or Just a Pause?
What is frustrating for patients and their health care providers:
Right now, there are no accurate and convenient tests to diagnose if you are in menopause from chemotherapy or are just having a temporary pause in fertility.
After chemotherapy:
- Having a period doesn’t always mean you’re releasing an egg
- Not having a period doesn’t always mean you can’t get pregnant
- Hormone tests (FSH, estradiol) and even ultrasounds can be misleading
- It can take months or years for your ovaries to show their true long-term function
That’s why, if you’re under 50, haven’t gone through natural menopause, are having sex that could result in pregnancy, and don’t want to become pregnant, it’s important to use birth control – regardless of whether periods have returned or what lab results show.