Introduction Cancer treatment during childhood may lead to late adverse effects, such as reduced musculoskeletal development or vascular, endocrine and pulmonary dysfunction, which in turn may have an adverse effect on later pregnancy and childbirth. The aim of the present study was to investigate pregnancy and obstetric outcomes as well as the offsprings health among childhood and adolescent female cancer survivors. Material and methods This register-based study included all women born between 1973 and 1977 diagnosed with cancer in childhood or adolescence (age amp;lt;21), as well as an age-matched comparison group. A total of 278 female cancer survivors with their first childbirth were included in the study, together with 829 age-matched individuals from the general population. Logistic regression and analysis of variance were used to investigate associations between having been treated for cancer and the outcome variables, adjusting for maternal age, nicotine use and comorbidity. Results Survivors were more likely to have preeclampsia (adjusted odds ratio [aOR] 3.46, 95% confidence interval [CI] 1.58 to 7.56), undergo induction of labor (aOR 1.66, 95% CI 1.05 to 2.62), suffer labor dystocia (primary labor dystocia aOR 3.54, 95% CI 1.51 to 8.34 and secondary labor dystocia aOR 2.43, 95% CI 1.37 to 4.31), malpresentation of fetus (aOR 2.02, 95% CI 1.12 to 3.65) and imminent fetal asphyxia (aOR 2.55, 95% CI 1.49 to 4.39). In addition, deliveries among survivors were more likely to end with vacuum extraction (aOR 2.53, 95% CI 1.44 to 4.47), with higher risk of clitoral lacerations (aOR 2.18, 95% CI 1.47 to 3.23) and anal sphincter injury (aOR 2.76, 95% CI 1.14 to 6.70) and emergency cesarean section (aOR 2.34 95% CI 1.39 to 3.95). Survivors used pain-reliving methods to a higher extent compared with the comparison group. There was no increased risk of neonate diagnoses and malformations. The results showed that survivors who had been diagnosed with cancer when they were younger than 14 had an increased risk of adverse obstetric outcomes. Conclusions The study demonstrates increased risk of pregnancy and childbirth complications among childhood and adolescent cancer survivors. There is a need to optimize perinatal care, especially among survivors who were younger than 14 at time of diagnosis.