Cancer During Pregnancy

Approved by the Cancer.Net Editorial Board, 11/2015

Cancer during pregnancy is uncommon. It occurs in only about one out of every 1,000 pregnancies. For many years, both doctors and women were often unsure about how to deal with cancer during pregnancy. But now more women with cancer and their doctors are starting or continuing treatment while pregnant. This means more information about treating and living with cancer during pregnancy is available than ever before.

Cancer itself rarely affects the growing baby directly. But having cancer while pregnant can be complicated for both the mother and the health care team. Therefore, it is important to find a doctor who has experience treating pregnant women with cancer. Learn more about finding an oncologist.

Types of cancers that occur during pregnancy

The cancers that tend to occur during pregnancy are also more common in younger people. These cancers include the following:

Breast cancer is the most common cancer diagnosed during pregnancy. It affects about one in 3,000 pregnancies. Because breasts typically enlarge and change texture during pregnancy, changes from cancer may be difficult to detect. Or, they may not appear to be abnormal. As a result, pregnant women with breast cancer may diagnosed later than non-pregnant women.

Diagnosing cancer during pregnancy

Being pregnant may delay a cancer diagnosis. This is because some cancer symptoms, such as bloating, headaches, breast changes, or rectal bleeding, are also common during pregnancy. On the other hand, pregnancy can sometimes uncover cancer. For example, a Pap test done as part of standard pregnancy care can detect cervical cancer. And an ultrasound performed during pregnancy could find ovarian cancer.

If cancer is suspected during pregnancy, women and their doctors may be concerned about diagnostic tests. More information on the safety of specific tests for pregnant women is listed below.

  • X-ray. Research has shown that the level of radiation in diagnostic x-rays is too low to harm the fetus. When possible, women may use a lead shield that covers the stomach for extra protection during x-rays.

  • Computed tomography (CT or CAT) scans. CT scans are similar to x-rays but are much more accurate. They can be very helpful in diagnosing cancer or showing whether the cancer has spread. And CT scans of the head or chest are usually safe during pregnancy because they don’t directly expose the fetus to radiation. When possible, women may use a lead shield that covers the stomach during CT scans. CT scans of the stomach or pelvis should be done only if absolutely necessary and after discussion with the medical team.

  • Other tests. Magnetic resonance imaging (MRI), ultrasound, and biopsy are generally considered safe during pregnancy because they don't use ionizing radiation.

Cancer treatment during pregnancy

When making treatment decisions for cancer during pregnancy, it is important to consider the best treatment options for the pregnant woman balanced against the possible risks to the growing baby.

Treatment recommendations are based on many factors, including the following:

  • Stage of the pregnancy

  • The type, location, size, and stage of the cancer

  • The woman’s and her family’s wishes

Treatment must be carefully planned to ensure the woman and unborn baby are safe. In general, treatment during pregnancy requires close teamwork with a multidisciplinary team, including both cancer doctors as well as high-risk obstetricians. These professionals can closely monitor the woman during treatment and make sure the baby is healthy.

Some cancer treatments are more likely to harm the fetus during the first three months of pregnancy. So, the doctor may delay treatment until the second or third trimesters. When cancer is diagnosed later in pregnancy, doctors may wait to start treatment until after the baby is born. In some cases, such as early-stage (stage 0 or IA) cervical cancer, doctors may wait to treat the cancer until after delivery.

Treatments that may be used during pregnancy

Some cancer treatments may be used during pregnancy. Treatments to consider include:

  • Surgery. Surgery is the removal of the tumor and some of the surrounding healthy tissue. It poses little risk to the growing baby and is considered the safest cancer treatment during pregnancy.

  • Chemotherapy. Chemotherapy is the use of drugs to destroy cancer cells. The drugs usually stop the cancer cells' ability to grow and divide. There is a risk of harm to the fetus if chemotherapy is given in the first three months of pregnancy. This is when the fetus's organs are still growing. Chemotherapy during the first trimester carries risk of birth defects or pregnancy loss.

    During the second and third trimesters, doctors can give several types of chemotherapy without apparent risk to the fetus. Because the placenta acts as a barrier between the women and the baby, some drugs cannot pass through, or they pass through in very small amounts. Studies have suggested babies exposed to chemotherapy while in the mother’s uterus do not show any abnormalities either immediately after delivery, or during their future growth and development, when compared with children not exposed to chemotherapy.

    Chemotherapy in the later stages of pregnancy may indirectly harm the baby by causing side effects in the woman. This side effects include low blood counts during delivery which can increase risk of infection.

    Doctors may suggest inducing labor early to protect the baby from cancer treatment for some women. However, it is preferred to continue the pregnancy until natural labor and delivery occurs. Babies born early may have a higher risk of health problems from being born early than those exposed to chemotherapy.

  • Radiation therapy. Radiation therapy is the use of high-energy x-rays to destroy cancer cells. Because radiation therapy can harm the fetus in all trimesters, doctors generally avoid using this treatment during pregnancy. The risks to the developing baby depend on the dose of radiation and the area of the body being treated.

Breastfeeding during treatment

Doctors advise women who are receiving chemotherapy after a pregnancy not to breastfeed. Chemotherapy can transfer to the infant through breast milk. Similarly, radioactive drugs that are taken internally, such as radioactive iodine used to treat thyroid cancer, may also get into breast milk and harm the infant.

How pregnancy affects risks from cancer

Pregnancy itself does not appear to affect the chance that they cancer treatment works. However, if a woman's diagnosis or treatment is delayed due to the pregnancy, the extent of the cancer may be larger. And this may lead to more risks associated with the cancer. Talk with your doctor about how pregnancy may affect your specific cancer risk and your recovery from therapy. 

Questions to ask the doctor

If you are pregnant and have recently been diagnosed with cancer, consider asking your doctor the following questions:

  • How much experience do you have treating pregnant women with cancer?

  • How will you work with my obstetrician?

  • Do I need to have any special tests?

  • What treatment plan do you recommend? Why?

  • Do I need to begin treatment right away, or should I wait?

  • Could delaying treatment affect my prognosis?

  • Is it safe to continue the pregnancy?

  • What are the short- and long-term risks of my treatment plan to me? To the baby?

  • Will treatment affect my delivery? How?

  • Will I be able to breastfeed?

  • What support services and other resources are available to me? To my family?

More Information

Having a Baby After Cancer: Pregnancy

Dating, Sex, and Reproduction

Being a Young Adult with Cancer

When the Doctor Says "Cancer"

Additional Resources

Hope for Two: The Pregnant with Cancer Network

MedlinePlus: Tumors and Pregnancy

National Cancer Institute: Breast Cancer Treatment and Pregnancy