This nationwide, population-based cohort study linked the Taiwan Cancer Registry, Birth Reporting Registry, and Death Registry to evaluate livebirths occurring after a first invasive cancer diagnosis at age ≤39 years among female residents. A total of 72,929 women met inclusion criteria and were followed to identify first post-diagnosis livebirths. The primary findings were that 9.8% of survivors had at least one livebirth after diagnosis, with 5-, 10-, and 15-year cumulative incidences of 6.4%, 10.7%, and 13.9%, respectively. Compared with the general female population, survivors had approximately half the expected number of births (Standardized Birth Ratio SBR = 0.50, 95% CI 0.49–0.51), indicating substantially reduced childbirth at the population level.
Study data were obtained through deterministic linkage using unique personal identification numbers. Cancer diagnoses, including type and date and first-course treatments, were obtained from the Taiwan Cancer Registry (records from 1979–2022). Livebirth data were drawn from the Birth Reporting Registry (2001–2023), which requires mandatory birth reporting. Mortality data were obtained from the Taiwan Death Registry through 2023. The cohort comprised all first invasive cancer diagnoses among women aged ≤39 years recorded in the Cancer Registry; cancer types were classified per ICD-O-3/WHO 2008 definitions and grouped into mutually exclusive categories.
Follow-up started at the date of cancer diagnosis, except for individuals diagnosed before age 15 years for whom follow-up began at age 15. Women were followed until the earliest of first post-diagnosis livebirth, age 49 years, death, or end of 2023. To ensure recorded births represented post-diagnostic conceptions, the study excluded women with less than one year of follow-up; births occurring within one year after diagnosis were therefore not included. The follow-up window for births was 2001–2023, matching the Birth Reporting Registry time span.
The primary outcome was first post-diagnosis livebirth. The 5-, 10-, and 15-year cumulative incidences were estimated using competing-risk methods with death treated as a competing event. Predictors of first livebirth were evaluated using cause-specific Cox proportional hazards models, yielding hazard ratios and 95% confidence intervals. Predictors examined included cancer type, age at diagnosis, calendar period of cancer onset, level of urbanization, and first-course cancer treatment. Multivariable models adjusted for cancer type, age at diagnosis, and period of cancer onset; treatment was not included in multivariable models because it was treated as a mediator rather than a confounder. Chronological trends across grouped categories were assessed by converting categories into ordinal scores and testing for linear trend. Proportional hazards assumptions were inspected graphically.
Across the cohort, 9.8% of female cancer survivors had at least one livebirth after diagnosis. Cumulative incidence estimates accounting for competing risk of death were 6.4% at 5 years, 10.7% at 10 years, and 13.9% at 15 years after diagnosis. Using indirect standardization against age- and calendar-year–specific birth rates in the general female population, the observed births among survivors were approximately half the expected number (SBR = 0.50, 95% CI 0.49–0.51).
The study found pronounced heterogeneity by cancer type. Childbirth rates were relatively preserved among survivors of thyroid and skin cancers. In contrast, survivors of cervical, uterine, breast, leukemia, and central nervous system cancers had markedly reduced childbirth compared with expectations. Older age at diagnosis was associated with a lower likelihood of subsequent childbirth. Receipt of chemotherapy (with or without surgery/radiation) was strongly associated with reduced probability of post-diagnosis livebirth. The authors reported that level of urbanization did not significantly affect childbirth probability in univariate analyses and thus was not included in multivariable models.
The authors situate their findings within Taiwan’s evolving fertility-preservation policy environment. In September 2025 the Ministry of Health and Welfare launched a national pilot subsidy program to support fertility preservation (oocyte cryopreservation for eligible female patients and sperm cryopreservation for eligible male patients aged 18–40 years with specified cancers before gonadotoxic treatment). The study’s population-level evidence of substantially reduced childbirth after cancer—especially for specific cancer types and in patients receiving chemotherapy—is presented as supporting the need for early fertility counseling and better access to oncofertility services and preservation measures.
Strengths of the study include nationwide registry linkage with comprehensive capture of cancer diagnoses and mandated birth reporting, a large sample of young female survivors, and competing-risk–adjusted cumulative incidence estimates. Limitations noted by the authors include the inability to include births within one year of diagnosis by design, potential residual confounding, and that treatment was not included in multivariable models because it was considered a mediator. The dataset cannot be publicly shared due to legal and ethical restrictions under Taiwan’s Personal Data Protection Act; researchers may apply for access through the Health and Welfare Data Science Center subject to review and ethics approval.
In this large, nationwide Taiwanese cohort, female cancer survivors diagnosed at age ≤39 years experienced substantially reduced childbirth rates compared with the general population, with clear variation by cancer type, age at diagnosis, and receipt of chemotherapy. The findings provide robust population-level evidence from an Asian context and underscore the importance of integrating fertility counseling and oncofertility access into cancer care and survivorship planning.