Modifiable and non-modifiable risk factors for preterm delivery among adolescent and young adult cancer survivors

Purpose: A cancer diagnosis in adolescence and young adulthood (AYA, ages 15–39) may affect future pregnancy outcomes. Previous studies have reported an increased risk of preterm delivery (< 37 weeks of gestation) after maternal cancer treatment. In this analysis, we evaluated whether non-cancer characteristics modify the association between an AYA cancer history and preterm birth. Methods: North Carolina Central Cancer Registry records (2000–2013) were linked to state birth certificate files (2000–2014) to identify births to AYA cancer survivors (n = 1,980). A comparison cohort of births to women without a cancer diagnosis was selected from birth certificate files (n = 11,860). Log-binomial regression was used to estimate risk ratios (RR) and 95% confidence intervals (CI) for preterm delivery. Effect modification by early prenatal care (1st trimester; yes/no), race/ethnicity (white/black/other), previous live births (0/1+), maternal age (< 25/25–29/30–34/35+), smoking during pregnancy (any/none), and education (high school or less/some college/Bachelor’s degree or higher) was evaluated using likelihood ratio tests (LRT). Results: Overall, preterm births were more common among AYA survivors than the comparison group (RR = 1.24, CI 1.07–1.43). The association was stronger among those who did not receive early prenatal care (RR = 1.73, CI 1.26–2.37) than among those who did (RR = 1.15, CI 0.98–1.35; LRT p = 0.03). Maternal age < 25 was also associated with a greater increase in preterm birth (< 25: RR = 1.80, CI 1.27–2.54; LRT p = 0.07). Associations did not vary strongly by other factors evaluated. Conclusions: An AYA cancer diagnosis may be associated with an increased risk of preterm birth, particularly among women who are younger and receive late or no prenatal care