Cancer Diagnosis During Pregnancy and Livebirth Outcomes in the Adolescent and Young Adult Horizon Study.

Objective: To describe patterns of cancer treatment and live birth outcomes that followed a cancer diagnosis during pregnancy. Study Design: The Adolescent and Young Adult (AYA) Horizon Study is an observational study evaluating outcomes in survivors of the five most common types of cancer in this age group (15-39 years old). Of the 23,629 individuals identified diagnosed with breast, lymphoma, thyroid, melanoma, or gynecological cancer in North Carolina (2000-2015) and California (2004-2016), we identified 555 live births to individuals who experienced cancer diagnosis during pregnancy. Births to individuals diagnosed with cancer during pregnancy were matched ∼1:5 on maternal age and year of delivery to live births to individuals without a cancer diagnosis (N = 2,667). Multivariable Poisson regression was used to compare birth outcomes between pregnancies affected by a cancer diagnosis and unaffected matched pregnancies. Results: Cancer diagnosis during pregnancy was associated with an increased risk of preterm delivery (prevalence ratio [PR] 2.70; 95% confidence interval [CI] 2.24, 3.26); very preterm delivery (PR 1.74; 95% CI 1.12, 2.71); induction of labor (PR 1.48; 95% CI 1.27, 1.73); low birth weight (PR 1.97; 95% CI 1.55, 2.50); and cesarean delivery (PR 1.18; 95% CI 1.04, 1.34) but not associated with low Apgar score (PR 0.90; 95% CI 0.39, 2.06). In our sample, 41% of patients received chemotherapy, half of whom initiated chemotherapy during pregnancy, and 86% received surgery, 58% of whom had surgery during pregnancy. Of the 19% who received radiation, all received radiation treatment following pregnancy. Conclusion: We identified an increased risk of birth outcomes, including preterm and very preterm delivery, induction of labor, low birth weight, and cesarean delivery, to those experiencing a cancer diagnosis during pregnancy. This analysis contributes to the available evidence for those experiencing a cancer diagnosis during pregnancy.