Pregnancy and Cancer

Last Updated: April 09, 2009

This section has been reviewed and approved by the Cancer.Net Editorial Board,  04/09

Cancer during pregnancy is rare and little research is available to guide women and doctors. It is known that a pregnant woman with cancer is capable of giving birth to a healthy baby and that some cancer treatments are safe during pregnancy.

Cancer occurs in approximately one out of every 1,000 pregnancies. However, pregnancy itself does not cause cancer, and pregnant women are not more likely to get cancer than other women. The cancers that tend to occur during pregnancy are those that are more common in younger people, such as cervical cancer and breast cancer, Hodgkin lymphoma, malignant melanoma, and thyroid cancer. Because age is the most significant risk factor for cancer, doctors expect the rate of cancer during pregnancy to increase as more women are waiting until they are older to have children.

Diagnosis

Being pregnant can delay a cancer diagnosis. Symptoms such as abdominal bloating, frequent headaches, or rectal bleeding might suggest ovarian, brain, or colon cancer. These symptoms are also common during pregnancy and are not considered suspicious. If these symptoms are related to cancer, diagnosis of the cancer is likely to be delayed.

Breast cancer is the most common cancer in pregnant women, affecting approximately one in 3,000 pregnancies. Pregnancy-related breast enlargement makes it difficult to detect small breast tumors, and mammograms are not regularly done during pregnancy.

If cancer is suspected during pregnancy, women and their doctors may be concerned about diagnostic tests such as x-rays. However, research has shown that the level of radiation in diagnostic x-rays is too low to harm the fetus (unborn baby). When possible, a lead shield covering the abdomen offers extra protection. Other diagnostic tests, such as magnetic resonance imaging test (MRI), ultrasound, and biopsy, are also considered safe during pregnancy because they don't use radiation.

Sometimes, pregnancy can uncover cancer that had previously gone undetected. For example, a Pap test performed as part of standard, early prenatal care can detect cervical cancer. Similarly, an ultrasound performed during pregnancy can often find ovarian cancer that might otherwise go undiagnosed.

Treatment

Treatment for cancer during pregnancy means balancing the best treatment for the mother with the possible risk to the fetus. The type of treatment given depends on many factors, including how far along the pregnancy is; the type, location, size, and stage of the cancer; and the wishes of the expectant mother and family. Because some cancer treatments can harm the fetus, especially during the first trimester (the first three months of pregnancy), treatment may be delayed 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, or they may consider inducing labor early. In some cases, such as early stage (stage 0 or IA) cervical cancer, doctors may wait to treat the cancer until after delivery.

Cancer treatments used during pregnancy may include surgery, chemotherapy, and possibly, radiation therapy, but only after careful consideration and treatment planning to optimize the safety of the mother and the unborn baby.

• Surgery poses little risk to the fetus and is considered the safest cancer treatment option during pregnancy. In some instances, more extensive surgery can be done to avoid having to use chemotherapy or radiation therapy.
  
  
• Chemotherapy is the use of drugs to kill cancer cells. Chemotherapy is capable of harming the fetus, particularly if given during the first trimester of pregnancy when the fetus' organs are still developing. Chemotherapy during the first trimester can cause birth defects or even the loss of the unborn baby. During the second and third trimesters, some types of chemotherapy can be taken without necessarily harming the fetus. The placenta (the organ that develops during pregnancy) acts as a barrier between the mother and the fetus, and the drugs cannot pass through the barrier (or they pass through only minimally). If the planned chemotherapy includes a drug that is not safe during any stage of pregnancy, another drug can usually be substituted.
  
  Although chemotherapy later in pregnancy may not directly harm the fetus, chemotherapy can cause health problems for the mother that can indirectly harm the fetus, such as malnutrition and anemia (low red blood cell count). Chemotherapy given during the second and third trimesters can cause early labor and low birth weight, both of which may lead to further health concerns for the mother, such as weight gain and problems with breast-feeding and fighting infections.
  
  
• Radiation therapy involves high energy x-rays to destroy cancer cells and shrink cancerous tumors. Because radiation therapy can harm the fetus, particularly during the first trimester, this treatment is generally not recommended. The use of radiation therapy in the second or third trimesters depends on the dose of radiation and the area of the body being treated.

The effects of cancer on the pregnancy

The prognosis (chance of recovery) for a pregnant woman with cancer is often the same as for another woman of the same age with the same type and stage of cancer. However, if a woman’s diagnosis is delayed during pregnancy, she will tend to have a worse, overall prognosis than a non-pregnant woman diagnosed with cancer. In addition, pregnancy can affect the behavior of some cancers. For example, there is some evidence to suggest that the hormonal changes of pregnancy may stimulate the growth of malignant melanoma.

Cancer rarely affects the fetus directly. Although some cancers can spread to the placenta, most cancers cannot spread to the fetus itself.

Breastfeeding

Although cancer cells cannot pass to the infant through breast milk, women who are being treated for cancer are generally advised not to breastfeed. Chemotherapy can be especially dangerous as it can build up in breast milk and harm the infant. Similarly, radioactive components that are taken internally, such as radioactive iodine used in treating thyroid cancer, also cross into breast milk and can harm the infant.

Pregnancy after cancer

As more young people are surviving cancer, more women are considering whether they should have a baby after having cancer. In general, pregnancy after cancer is considered safe for both the mother and the baby, and pregnancy does not appear to increase the chances of cancer recurring (coming back). However, since some cancers do recur, women are usually advised to wait a number of years after completing cancer treatment until the risk of recurrence has decreased. The amount of time you will be advised to wait before becoming pregnant depends on the type and stage of cancer and course of treatment. Learn more about having a child after cancer treatment.

Sometimes, cancer treatments can damage specific areas of the body such as the heart or lungs. Before becoming pregnant, your doctor may need to evaluate these organs to be sure that the pregnancy will be safe.

Unfortunately, some cancer treatments can also cause infertility, making it difficult or impossible for some women to have children. Read more about fertility and cancer treatment and fertility options for men and women.

More Information

Cancer in Young Adults

Additional resources

Hope for Two: The Pregnant with Cancer Network

National Cancer Institute: Breast Cancer and Pregnancy

American Cancer Society: Pregnancy and Breast Cancer