Prenatal X-ray exposure and childhood cancer in Swedish twins

Int J Cancer. 1990 Sep 15;46(3):362-5. doi: 10.1002/ijc.2910460304.


The association between X-ray exposure in utero and childhood cancer was studied in a case-control study, nested in a national cohort of Swedish twin births. Records of the Swedish Twin Register for those born 1936-1967 (n = 83,316) were linked to the Swedish Cancer Register (1958-1983) and the Swedish Cause-of-Death Register (1952-1983). Ninety-five cases of childhood cancer before the age of 16 were identified. Two controls from the Twin Register were matched to each case by sex and year of birth. Maternal X-rays during pregnancy were documented for 41% of the cases and 36% of the controls. The crude relative risk of any childhood cancer associated with any prenatal X-ray was 1.2 (95% CI; 0.7-2.1). For the cases 64% of the X-rayed women had had abdominal X-rays, the numbers for the controls were 57%. Fifty-nine per cent of the X-rayed women had had abdominal X-rays, which were associated with a relative risk for all cancers of 1.4 (Cl; 0.8-2.5), leukemias 1.7 (Cl; 0.7-4.1) and tumors of the central nervous system 1.5 (Cl; 0.5-4.2). There was no apparent confounding by mother's age, drug use, obstetric complications, previous miscarriages, social class or length of pregnancy. The observed relative risks of cancer following prenatal X-ray exposure are consistent with previous studies, suggesting that the developing fetus may be more sensitive to the carcinogenic effects of ionizing radiation than are children irradiated post-natally.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • Cohort Studies
  • Embryonic and Fetal Development / radiation effects
  • Female
  • Humans
  • Male
  • Maternal Age
  • Neoplasms, Radiation-Induced / epidemiology*
  • Pregnancy
  • Prenatal Exposure Delayed Effects*
  • Radiography / adverse effects*
  • Registries
  • Risk Factors
  • Sex Factors
  • Sweden
  • Twins*