Cancer During Pregnancy

Approved by the Cancer.Net Editorial Board, 11/2016

Cancer during pregnancy is uncommon. For many years, health care providers and women were often unsure about how to deal with cancer during pregnancy. Now, more women with cancer are starting or continuing treatment during pregnancy. This means we have more information about treating and living with cancer during pregnancy 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 health care provider 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:

Breast cancer is the most common cancer diagnosed during pregnancy. It affects about 1 in 3,000 women who are pregnant. 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 be 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 find cervical cancer. And an ultrasound performed during pregnancy could find ovarian cancer.

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

  • X-ray. Research shows 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 abdomen 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. 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 abdomen during CT scans. CT scans of the abdomen 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 safe during pregnancy. These tests do not use ionizing radiation.

Cancer treatment during pregnancy

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

Treatment recommendations are based on many factors, including:

  • Stage of the pregnancy

  • Type, location, size, and stage of the cancer

  • The woman’s and her family’s wishes

Treatment must be carefully planned to make sure the woman and unborn baby are safe. In general, treatment during pregnancy requires close teamwork with a multidisciplinary team. This includes cancer doctors and 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 3 months of pregnancy. So the health care provider may delay treatment until the second or third trimesters. When cancer is diagnosed later in pregnancy, health care providers may wait to start treatment until after the baby is born. In some cases, such as early-stage (stage 0 or IA) cervical cancer, health care providers may wait to treat the cancer until after delivery.

Some treatments, such as radiation therapy, can harm the fetus in all trimesters. So health care providers generally avoid using this treatment during pregnancy. Radiation therapy uses high-energy x-rays to destroy cancer cells. The risks to the developing baby depend on the radiation dose and the area of the body being treated.

Treatments that may be used during pregnancy

Cancer treatments that may be used during pregnancy include:

  • Surgery. During surgery, doctors remove 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. Doctors use chemotherapy drugs to destroy cancer cells. The drugs usually stop the ability of cancer cells to grow and divide. There is a risk of harm to the fetus if chemotherapy is given in the first 3 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 woman and the baby, some drugs cannot pass through. Others can pass through only in small amounts. Studies suggest that babies exposed to chemotherapy while in the mother’s uterus do not show abnormalities immediately after delivery or during growth and development, as compared to children not exposed to chemotherapy.

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

Health care providers may suggest inducing labor early to protect the baby from cancer treatment. But it is preferred to continue the pregnancy until natural labor and delivery occurs. Babies born early may have a higher risk of health problems than babies exposed to chemotherapy.

Breastfeeding during treatment

Health care providers 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 how well the 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. This may lead to more risks associated with the cancer. Talk with your health care provider about how pregnancy may affect your cancer risk and recovery from therapy. 

Questions to ask your health care provider

If you are pregnant and have recently been diagnosed with cancer, consider asking your health care provider these 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 chance of recovery?

  • 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