This Ontario province wide cohort study was conducted to compare the risk o
f adverse pregnancy outcomes in female childhood cancer survivors who recei
ved abdominal pelvic radiation and/or chemotherapy with alkylating agents w
ith the risk among those who were treated by non sterilizing alkylating age
nts with the risk among those who were treated by non-sterilizing surgery o
nly. Females in Ontario, Canada, diagnosed in 1964-1988 before age 20 with
a histologically confirmed malignancy and who had survived for at least 5 y
ears, attained age 18, and were alive at the time of study, were identified
through the Ontario Cancer Registry. We ascertained pregnancy outcomes by
a telephone-administered questionnaire. Treatment data were abstracted from
medical records for 830 subjects 18-49 years of age, the analysis comprise
d 340 survivors who had one or more pregnancies after treatment. There was
no evidence of an increased risk of having a spontaneous abortion or an inf
ant with a birth defect. Survivors receiving abdominal-pelvic radiation wer
e more likely to have a low birth weight infant (odds ratio estimate [OR] =
3.64; 95% confidence interval [CI] = 1.33-9.96), a premature low birth wei
ght infant (OR = 3.29; 95% CI = 0.97-11.1), or an infant who died in the pe
rinatal period (OR = 2.41; 95% CI = 0.50-11.5), compared with those receivi
ng surgery. Risks of perinatal death and having a low birth weight infant i
ncreased with dose of radiotherapy directed to the abdomen.