When a woman receives a cancer diagnosis during pregnancy, the stakes feel impossibly high: her life, her baby's safety, and her future ability to have children all hang in the balance. A groundbreaking Swedish study of 50 women diagnosed with pregnancy-associated cancer (PAC) shows that fertility preservation techniques can help protect a woman's reproductive future, even as she undergoes urgent cancer treatment. Among the women who pursued fertility preservation, 13% remained childless at the end of follow-up, compared to 20% in the group that did not pursue these options .

What Is Pregnancy-Associated Cancer and How Common Is It?

Pregnancy-associated cancer occurs when a woman is diagnosed with cancer either during pregnancy or within one year after delivery. Researchers at Karolinska University Hospital in Sweden tracked all patients referred for fertility preservation counseling between 2001 and 2024, creating a prospective cohort study that followed women for an average of 9.9 years . The most common cancers diagnosed during or shortly after pregnancy were breast cancer (62% of cases), cervical cancer (12%), and lymphoma (10%) .

Among the 50 women in the study, 79% were diagnosed while pregnant, and 21% were diagnosed up to one year after delivery. The timing of diagnosis significantly influenced treatment decisions. Most women diagnosed in the first trimester either terminated their pregnancies or experienced miscarriage (76%), while all women diagnosed in the second or third trimesters delivered via cesarean section, with deliveries scheduled from week 31 onward .

What Fertility Preservation Options Are Available for Pregnant Women With Cancer?

Fertility preservation techniques allow women to freeze their eggs, embryos, or ovarian tissue before undergoing chemotherapy or radiation, which can damage reproductive organs. The Swedish study documented three primary approaches that women pursued :

• Ovarian Stimulation and Egg/Embryo Freezing: This involves hormone treatment to stimulate egg production, followed by retrieval and freezing of eggs or embryos before cancer treatment begins. In the study, 43% of women in the fertility preservation group chose this method.
• Ovarian Tissue Cryopreservation (OTC): This procedure removes and freezes ovarian tissue, which can be transplanted back later to restore fertility. Among the fertility preservation group, 57% underwent OTC either after delivery or following abortion/miscarriage, while 10 women had OTC performed at the time of cesarean delivery.
• Delayed Fertility Preservation: Some women pursued fertility preservation after completing cancer treatment. In the study, four women proceeded with this approach, three through ovarian tissue freezing and one through attempted hormone stimulation, though the latter was unsuccessful.

The timing of fertility preservation matters significantly. Women diagnosed in early pregnancy who chose to continue their pregnancies could plan ovarian tissue freezing at the time of their scheduled cesarean delivery, integrating the procedure into their existing surgical plan. Those who terminated pregnancies or experienced miscarriage could pursue egg or embryo freezing before chemotherapy initiation .

How Do Treatment Decisions Change Based on When Cancer Is Diagnosed?

The trimester in which cancer is diagnosed dramatically shapes the treatment pathway. Women diagnosed in the first trimester faced the most difficult decisions: 76% either terminated their pregnancies or experienced miscarriage, allowing them to pursue aggressive cancer treatment without concern for fetal safety . These women had the option to pursue ovarian stimulation for egg or embryo freezing before chemotherapy began.

Women diagnosed in the second or third trimester took a different approach. All 14 women in the study diagnosed during these later stages delivered via cesarean section, with deliveries scheduled from week 31 onward. Importantly, all women diagnosed in the third trimester delayed cancer treatment until after delivery, allowing them to carry their pregnancies closer to term . This timing created an opportunity to perform ovarian tissue cryopreservation at the time of cesarean delivery, integrating fertility preservation into their surgical plan.

What Were the Long-Term Outcomes for Women Who Pursued Fertility Preservation?

The study followed 50 women for an average of 9.9 years, with 45 patients alive at the end of follow-up. Among the 30 women who chose to pursue fertility preservation, outcomes were encouraging. The proportion of women who had children before their cancer diagnosis was similar in both the fertility preservation group and the group that did not pursue these options. However, by the end of follow-up, the fertility preservation group showed better outcomes: only 13% of women in the fertility preservation group remained childless, compared to 20% in the no-fertility-preservation group .

These results suggest that fertility preservation techniques, when pursued during or shortly after pregnancy-associated cancer diagnosis, can meaningfully improve the likelihood of future parenthood for cancer survivors.

What Gaps Exist in Current Guidelines for Pregnancy-Associated Cancer?

Despite the clear benefits of fertility preservation, the Swedish researchers identified a critical gap in medical guidance. Current fertility preservation guidelines lack specific recommendations for women with pregnancy-associated cancer, and specialized pregnancy-associated cancer guidelines similarly lack detailed information about fertility preservation options . This gap means that women facing this rare but serious situation may not receive comprehensive counseling about their reproductive options.

The researchers emphasized the importance of multidisciplinary communication. When a woman is diagnosed with cancer during or shortly after pregnancy, her care team should include oncologists, obstetricians, reproductive endocrinologists, and fertility specialists working together to inform patients about the future risk of infertility and the available fertility preservation procedures. The study was registered with ClinicalTrials.gov (identifier NTC04602962) and represents one of the most comprehensive long-term follow-up studies of fertility preservation in women with pregnancy-associated cancer .

Steps to Take If You're Diagnosed With Cancer During Pregnancy

• Seek Multidisciplinary Care Immediately: Request a team approach involving your oncologist, obstetrician, and a reproductive endocrinologist or fertility specialist who can discuss all available options, including fertility preservation techniques.
• Discuss Fertility Preservation Options Early: Ask specifically about ovarian stimulation and egg/embryo freezing, ovarian tissue cryopreservation, and the timing of these procedures relative to your cancer treatment and pregnancy management.
• Understand Your Trimester-Specific Options: Work with your care team to understand how the timing of your cancer diagnosis affects both your pregnancy management and fertility preservation choices, including whether delivery timing can be coordinated with fertility preservation procedures.
• Ask About Long-Term Follow-Up: Ensure your care plan includes long-term monitoring and support for pursuing future pregnancies after cancer treatment, as fertility outcomes may take years to fully realize.

The Swedish study provides hope for women facing the intersection of pregnancy and cancer diagnosis. By ensuring comprehensive counseling and coordinated multidisciplinary care, women can make informed decisions about both their immediate cancer treatment and their long-term reproductive goals.