# Trends and outcomes of fertility preservation in patients presenting with cancer during pregnancy or postpartum—a longitudinal observational cohort study

## TL;DR

This study examines how women with cancer during or after pregnancy choose and benefit from fertility preservation methods, highlighting the need for better guidelines and communication.

## Contribution

The study provides longitudinal insights into fertility preservation trends and outcomes for women with pregnancy-associated cancer.

## Key findings

- Most women diagnosed in the first trimester terminated the pregnancy or experienced miscarriage.
- FP was most commonly performed postpartum or post-abortion, with 57% undergoing ovarian tissue cryopreservation.
- At follow-up, 13% of women in the FP group remained nulliparous compared to 20% in the no-FP group.

## Abstract

The aim of this study was to assess the trends and outcomes of fertility preservation (FP) in women referred for FP counseling and presenting with pregnancy-associated cancer (PAC).

This is a prospective cohort study of all patients referred for FP counseling between 2001 and 2024 to the FP program of Karolinska University Hospital, Sweden. Baseline data, age, parity, disease stage, treatment characteristics, and FP methods were retrieved from clinical registries.

A total of 50 women with cancer diagnosed coincidentally with pregnancy (79%) or up to 1 year after delivery (21%) were referred for FP counseling. Among them, 30 women chose to proceed with FP; 10 by either hormonal stimulation to freeze eggs/embryos or ovarian tissue cryopreservation (OTC) after abortion/miscarriage, 10 by OTC at delivery, and 9 were planned for FP postpartum. The most common cancers were breast cancer (N = 31, 62%), cervical cancer (N = 6, 12%), and lymphoma (N = 5, 10%). Most women diagnosed with cancer in the first trimester either terminated the pregnancy or had a miscarriage (76%). All patients diagnosed in the second and third trimesters delivered through cesarian section (N = 14), scheduled from week 31 and onwards. All patients diagnosed in the third trimester started cancer treatment postpartum. In the FP group, 57% cryopreserved ovarian tissue postpartum or post-abortion and 43% underwent ovarian stimulation for oocyte/embryo cryopreservation prior to chemotherapy initiation. Four women proceed to FP after chemotherapy, three by ovarian tissue freezing and one through attempted, unsuccessful, hormonal stimulation. After a mean follow-up of 9.9 years, 45 patients were alive. The proportion of women having previous children at diagnosis was the same among the FP and no-FP groups. At the end of follow-up, the percentage of nulliparous women was 20% in the no-FP group and 13% in the FP group.

Our observations underscore the need to ensure good multidisciplinary communication to inform patients presenting with PAC on the future risk for infertility and on the available FP procedures. As FP has to be applied when the patients are not pregnant, these measures can be planned in connection with a cesarean section, or after completion of cancer treatment. Current guidelines for FP lack specific recommendations for women with PAC, and specialized PAC guidelines also lack specific information on FP. Clinical Trial Registration: ClinicalTrials.gov, identifier NTC04602962.