Pregnancy after adolescent and adult cancer: a population-based matched cohort study.

Despite fertility-preserving initiatives, postcancer reproduction is expected to be lower than that of the general population. Using data from the Cancer Registry and the Medical Birth Registry of Norway, postcancer pregnancy rates were analyzed in 27,556 survivors and compared to those from a matched comparison group ("controls") from the general population. All were born after 1950, diagnosed from 1967 to 2004 at age of 16-45, and had an observation time from the date of diagnosis (assigned date for controls), until pregnancy, death, age 46, or December 31, 2006. Cox regression was used to estimate pregnancy rates, after adjusting for educational level, parity and diagnostic period. Overall, cancer survivors had a lower pregnancy rate than the controls, but the rate for survivors was higher in males than in females [hazard rate (HR)=0.74 (95% confidence interval (CI) 0.71-0.78) and HR=0.61 (95% CI 0.58-0.64), respectively]. However, the rates did not differ between controls and survivors of malignant melanoma or thyroid cancer. By contrast, the lowest HRs for pregnancy occurred in survivors of leukemia, cervical or breast cancer. Increased pregnancy rates during the study period were detected for ovarian cancer [HR=0.2 (95% CI 0.1-0.3) to HR=0.7 (95% CI 0.5-0.9)], testicular cancer [HR=0.6 (95% CI 0.4-0.9) to HR=0.8 (95% CI 0.7-0.8)], and Hodgkin lymphoma diagnosed in men [HR=0.7 (95% CI 0.5-0.9) to HR=0.9 (95% CI 0.7-1.0)]. In summary, fertility-preserving attempts have succeeded in patients with ovarian or testicular cancer and in males with Hodgkin lymphoma. Male survivors initiated pregnancies in a higher degree than female survivors.