As abortion bans go into effect across a contiguous swath of the South, cancer physicians are wrestling with how new state laws will influence their discussions with pregnant patients about what treatment options they can offer.

Cancer coincides with roughly 1 in 1,000 pregnancies, most frequently breast cancer, melanoma, cervical cancer, lymphomas, and leukemias. But medications and other treatments can be toxic to the developing fetus or cause birth defects. In some cases, hormones that are supercharged during pregnancy fuel the cancer’s growth, putting the patient at greater risk.

Although new abortion restrictions often allow exceptions based on “medical emergency” or a “life-threatening physical condition,” cancer physicians describe the legal terms as unclear. They fear misinterpreting the laws and being left in the lurch.

For instance, brain cancer patients have traditionally been offered the option of abortion if a pregnancy might limit or delay surgery, radiation, or other treatment, said Dr. Edjah Nduom, a brain cancer surgeon at Emory University’s Winship Cancer Institute in Atlanta.