Pregnancy outcomes among female childhood, adolescent, and young adult cancer survivors assessed using internet-based nationwide questionnaire surveys in Japan

Female cancer survivors planning to become pregnant are concerned about the impact of cancer treatment on their ability to maintain normal pregnancy and the negative impact on their offspring. However, studies on the pregnancy outcomes of cancer survivors in Japan are limited. Therefore, this study aimed to investigate the pregnancy outcomes of female cancer survivors by comparing them with women without a history of malignant tumors in Japan.This cross-sectional study included 3308 subjects, based on an internet-based questionnaire (self-reported) survey conducted in Japan. Differences in pregnancy outcomes, including multiple pregnancies, stillbirth, preterm birth (PTB), and infant birthweight, between cancer survivors and subjects without a history of malignant tumors, were evaluated using a generalized linear mixed-effects model with adjustment for possible confounding factors.Of 3308 subjects included in this study, 629 (19.0%) were cancer survivors, among whom cervical (40.4%), breast (19.1%), and thyroid (7.0%) malignancies were most frequent. 71 (2.2%) and 53 (1.6%) participants had a history of multiple pregnancies and stillbirth, respectively; 385 (11.8%), 179 (5.5%), and 137 (4.2%) participants, respectively, had histories of PTB at less than 37, 34, and 32 weeks of gestation. Further, 302 (10.7%), 326 (11.6%), and 330 (11.7%) participants delivered to low birthweight (LBW), small-for-gestational-age (SGA), and large-for-gestational-age (LGA) infants, respectively. Subjects with a history of cervical or breast cancers had significantly higher odds of PTB at <37 weeks of gestation (adjusted odds ratios [ORs], 1.87 [95% CI: 1.25-2.81] and 2.61 [95% CI: 1.77-3.86], respectively), preterm LBW infants (adjusted ORs, 2.70 [95% CI: 1.39-5.24] and 2.76 [95% CI: 1.03-7.38], respectively), and LGA infants (1.98 [95% CI: 1.36-2.89] and 1.99 [95% CI: 1.14-3.49], respectively), compared to those without a history of a malignant tumor. Subjects with a history of thyroid cancer had significantly higher odds of stillbirth (adjusted OR, 5.11 [95% CI: 1.11-23.5]).Cancer survivors had a higher risk of adverse pregnancy outcomes than those without a history of malignant tumors in Japan. Healthcare providers should consider the high likelihood of adverse pregnancy outcomes during preconception counseling for cancer survivors.