SMFM Issues New Clinical Guidance for Cancer Diagnosis and Treatment During Pregnancy

Washington, DC – As the incidence of cancer among reproductive-age people continues to increase in the U.S., with approximately one out of every 1,000 pregnancies complicated by cancer, the Society for Maternal-Fetal Medicine (SMFM) today issued its first evidence-based clinical guidance for diagnosing and treating cancer during pregnancy. SMFM Consult Series #76: Cancer in pregnancy, endorsed by the American College of Obstetricians and Gynecologists, is published in PREGNANCY.  

The increase in the average maternal age may partially explain the rising prevalence of cancer during pregnancy, but improved cancer screening rates and increased exposure to environmental triggers also play a role. Additionally, the expanded use of cell-free DNA (cfDNA) prenatal genetic screening has led to increased maternal detection of both preclinical and metastatic cancers, according to SMFM’s new guidelines.  

“As cancer rates continue to rise, clinicians are seeing more patients with cancer during pregnancy, but guidance has been limited until now. This document brings together the best available evidence to help manage pregnant patients with cancer while supporting both maternal health and pregnancy goals,” said Moti Gulersen, MD, MSc, a maternal-fetal medicine subspecialist at Sidney Kimmel Medical College of Thomas Jefferson University in Philadelphia, PA, and a member of the SMFM  Publications Committee that led the development of the new guidelines. “Importantly, advances in oncology and multidisciplinary care mean that many patients can safely receive treatment during pregnancy, allowing us to prioritize both effective cancer therapy and fetal well-being.”  

The overall incidence of cancer before age 50 in the U.S. has increased since 2010, disproportionately impacting females. Breast cancer, one of the most common cancers in pregnancy, affects up to one in 3,000 pregnancies. Ten percent of thyroid cancers are now diagnosed during pregnancy or within one year postpartum, and three percent of people with Hodgkin lymphoma are pregnant when they are diagnosed. 

Historically, there has been limited research on maternal and infant health after cancer treatment during pregnancy. This lack of information about the potential impact of cancer treatment on the fetus resulted in a general avoidance of it during pregnancy. However, recent data have demonstrated reassuring health outcomes after treatment for many types of cancer in pregnancy.  

“We want to emphasize the importance of assembling a multidisciplinary, patient-centered care team for our pregnant patients diagnosed with cancer,” said Gulersen. “Cancer treatment will need to be individualized based on the type and stage of cancer, the stage of pregnancy, and our patient’s desire to continue the pregnancy.”

The new guidance includes recommendations and considerations on the diagnosis and management of breast, cervical, colorectal, Hodgkin lymphoma, leukemia, melanoma, non-Hodgkin lymphoma, ovarian, and thyroid cancers. The guidance also addresses the maternal and fetal risks, benefits, and timing of various cancer treatments, such as radiation, chemotherapy, and surgery.  

Recommendation highlights include: 

• Cancer treatment should not be withheld based on pregnancy status alone, and all patients should have access to the full range of reproductive options. 

• Ultrasonography and noncontrast magnetic resonance imaging (MRI) are suggested as first-line imaging techniques in pregnancies with suspected cancer. 

• Surgery for cancer should not be delayed or withheld from a pregnant patient at any gestational age.  

• Starting treatment to prevent blood clots (thromboprophylaxis) is recommended for all patients with active hematological or gynecological cancers during pregnancy; thromboprophylaxis should be considered for pregnant patients with other cancer types, based on individual risk factors. 

• Chemotherapy is generally recommended to be given after 12 weeks of gestation. If a patient diagnosed in the first trimester wants to continue the pregnancy, discussion with oncology should include whether delaying treatment until after 12 weeks of gestation is expected to significantly change the prognosis.  

• Serial fetal growth surveillance is recommended every three to four weeks in pregnancies with an active cancer diagnosis, regardless of treatment type. 

SMFM Consult Series #76: Cancer in pregnancy is available here.  

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