The patient had already made the agonizing decision to start chemotherapy to address her colon cancer, even though she was 30 weeks pregnant. Within a day, the decisions got harder: her colon perforated, and the pain was excruciating. She would need urgent surgery — and she would have to undergo an emergency C-section immediately.

“She looked me in the eye, and she said, ‘I have two children that need me, and if you have to make a decision, I need you to remember that. That my little girls need me, the two kids I already have need me,’” said her oncologist, Katherine Van Loon, who specializes in treating gastrointestinal cancers at the University of California, San Francisco.

Pregnant cancer patients like Van Loon’s have always faced near-impossible choices between their lifesaving cancer treatments and their unborn children. But in a post-Dobbs America, restrictions on abortion access threaten to take the choice out of the patients’ hands, or those of their doctors.

Right now, one in 1,000 pregnancies is affected by a concurrent cancer diagnosis each year, a number that could rise as the mean age for pregnancy in the U.S. continues to trend upward. Many chemo, radiation, and hormone therapies can cause fetal harm, particularly during the first trimester. This can include congenital birth defects, higher stillbirth rates, and low birthweight and blood counts. Severe complications from the disease, such as those experienced by Van Loon’s colon cancer patient, may also force decisions on whether to prioritize the mother or the fetus.