Background: Women who survive cancer diagnosed in childhood, adolescence or young adulthood may develop long-term health issues. Data are lacking on adverse reproductive outcomes such as infertility and obstetrical and perinatal complications. Methods: Using linked Ontario provincial cancer and obstetrical registries, we assembled a cohort of female cancer survivors diagnosed before age 21 years from 1985-2012. We matched survivors by age and geographic region to females without a prior cancer diagnosis. Outcomes included i) any recognized and past 20 weeks’ gestation pregnancy; ii) perinatal complications; and iii) obstetrical complications (including a broad composite of severe maternal morbidity [SMM]). Multivariable Cox proportional hazard and modified Poisson models compared survivors to a non-cancer group and assessed demographic, diagnostic and treatment risk factors in survivors. Results: 3,486 survivors were matched to 17,428 women without prior cancer. Median age at cancer diagnosis was 12 years (IQR 5-16) and median follow-up was 26 years (IQR 21-32). 599 (17.2%) survivors had at least one recognized pregnancy compared to 3,885 (22.3%) women without prior cancer (Hazard Ratio [HR] 0.79, 95% Confidence Interval [CI] 0.7-0.9, p < .0001). Among those who had a recognized pregnancy, 581 (97.0%) survivors carried a pregnancy > 20 weeks’ gestation vs. 3791 (97.6%) in the non-cancer group (Relative Risk [RR] 1.0, CI 0.98-1.04). Factors significantly associated with a decreased likelihood of achieving at least one recognized pregnancy among survivors included brain tumour, cranial radiation, exposure to an alkylating agent or hematopoietic stem cell transplantation (HSCT). Among women who had a livebirth or stillbirth, survivors had a RR of 2.3 (CI 1.5-3.6) for SMM and 3.2 (CI 1.6-6.6) for cardiac morbidity. Factors associated with SMM among survivors included brain tumour and pre-existing kidney disease. Among livebirth pregnancies, cancer survivors were at higher risk of preterm birth (RR 1.6, CI 1.2-2.0), especially those who received an alkylating agent or HSCT. Conclusions: Survivors of childhood, adolescence or young adulthood cancer are less likely to achieve a recognized pregnancy compared to women without prior cancer. Those who carry a pregnancy >20 weeks’ gestation are at higher risk for SMM and preterm birth. Fertility planning and counseling can be informed by cancer diagnosis and treatment, and high-risk obstetrical care is recommended for survivors at elevated risk of an adverse pregnancy outcome.

CIHR Restracomp SickKids Scholarship