Will Your Periods Come Back After Chemotherapy?

If your periods continue through much of your chemotherapy treatment, your chance of future fertility is better.

If your periods have stopped, the chances of them coming back depend on your age and the types and doses of chemotherapy drugs you get.

If you're under 35, there's a good chance your periods will return after six months, but it could take up to a year. In some women, it may even take up to two years. The longer it takes for your periods to come back, the more limited your fertility might be when they do come back.

Another factor that can influence how soon your periods come back is whether you're on tamoxifen. This drug may slow the return of your periods and it may make them irregular when they come back. In this situation, the length of time it takes for your periods to return may not be as meaningful in terms of predicting your future fertility.

Blood tests to see if you're in menopause

Six months after treatment ends, you can have your hormone levels tested. These tests are pretty accurate at telling whether you're in menopause.

If the test results show that you are not in menopause, this means you may still be fertile. But it doesn't necessarily mean that it will be as easy for you to get pregnant as it was before treatment. Even when your periods come back, your fertility level after treatment will probably be lower. Fertility may be reduced by the chemotherapy, ongoing hormonal therapy, and just because you are a little older.

Several blood tests for menopause measure the levels of different hormones in your body:

• follicle-stimulating hormone (FSH),
• leutinizing hormone (LH), and
• estradiol.

The levels of these hormones go up and down during the menstrual cycle. They stimulate the ovaries to produce eggs each month.

When you're fertile, production of these hormones stops once the ovaries respond to them by getting an egg ready for ovulation. Production of the hormones starts again at the beginning of your next cycle.

But if your ovaries are beyond menopause, they don't respond to the hormones. Yet the brain keeps sending messages out to make more hormones. This means the levels of the hormones remain high all the time — they no longer go up and down each month.

So if your periods do not return after chemotherapy — but your FSH, LH, and estradiol levels remain elevated six months later — your ovaries are probably beyond menopause. It is likely that you will remain infertile, but it is also still possible that your menstrual periods will return.

Sometimes the FSH and LH can be high six months after your treatment is over, but later fall back down to normal premenopausal levels with the return of your periods. It can be very frustrating dealing with this uncertainty. But right now we just don't have enough research in this area to make better predictions.

While you're waiting for your periods to come back, take the time to heal. Even if you were to get your periods back within the first six months, most doctors would still recommend that you wait at least six months after chemotherapy is over before trying to get pregnant.

If and when your periods come back

After your periods come back and after you've waited until your doctors say it's OK to try to get pregnant, you may still benefit from fertility treatment. This is because you may go into menopause earlier than you would have without having had chemotherapy.

The reason is that chemotherapy can damage the immature, or unripe, eggs in the ovaries. And research has shown that the lower the number of immature eggs in the ovaries, the earlier women go through menopause.

This is why it is recommended that all women who are pre-menopausal before breast cancer treatment — and who would like to have children some time in the future — see a fertility expert BEFORE starting treatment. Talking to an expert will give you the information you need to decide what steps to take to increase your chances of having one or more pregnancies after treatment.