Trends in cancer during pregnancy and adverse neonatal outcome: a nationwide population-based study in Taiwan

BACKGROUND: Cancer has remained a leading cause of death worldwide. Although relatively rare during pregnancy, cancer poses significant risks to both maternal and fetal health. With the continuous rise in maternal age, the incidence of cancer during pregnancy is expected to increase. In this nationwide, population-based epidemiological study, we aimed to assess temporal trends in the incidence of cancer during pregnancy and evaluate its association with adverse neonatal outcomes. METHODS: We analyzed nationwide data from the Taiwan National Health Insurance Research Database, Taiwan Cancer Registry, Birth Reporting Database, and Maternal and Child Health Database from 2011 to 2020. Pregnant women younger than 18 or older than 45 years, with missing or incomplete data, or with a history of cancer before pregnancy were excluded. Annual percentage change in cancer incidence during pregnancy was estimated using the Joinpoint Regression Program, and neonatal outcomes were evaluated using age-standardized incidence ratios across four maternal age categories (< 30, 30–34, 35–39, ≥ 40 years). RESULTS: Among identified 1,790,456 pregnancies, 504 (0.03%) women were diagnosed with cancer. The mean annual incidence was 28.2 per 100,000 pregnancies, demonstrating an increasing trend without statistical significance (annual percentage change: 3.84%; p = 0.094), which corresponded with increasing maternal age. Breast and cervical cancers were the most frequently diagnosed malignancies, with a significant rise in breast cancer diagnosed during pregnancy over the study period (p = 0.005). After standardization for maternal age, neonates born to mothers diagnosed with cancer during pregnancy exhibited higher age-standardized incidence rates of preterm birth, low birth weight, and low 1-minute and 5-minute Apgar scores, compared to those born to mothers without cancer. However, no significant differences were observed in the incidence of neonatal mortality or congenital anomalies. CONCLUSIONS: Cancer during pregnancy is associated with adverse short-term neonatal outcomes. Further research is warranted to elucidate causal mechanisms and assess the long-term health implications for offspring.