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Exclusion of Pregnant Women

Exclusion of Pregnant Women. Henry D. Royal, M.D. Associate Director Division of Nuclear Medicine Mallinckrodt Institute of Radiology Professor of Radiology Washington University School of Medicine St. Louis, MO. FDA Meeting 11/16/04. Overview. Radiation Risks During Pregnancy

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Exclusion of Pregnant Women

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  1. Exclusion of Pregnant Women Henry D. Royal, M.D. Associate Director Division of Nuclear Medicine Mallinckrodt Institute of Radiology Professor of Radiology Washington University School of Medicine St. Louis, MO FDA Meeting 11/16/04

  2. Overview • Radiation Risks During Pregnancy • Pregnancy Tests • Mutagenesis

  3. Radiation Effects in Pregnancy • Dose to Embryo and Fetus • Stage of Gestation • Congenital Abnormalities are Deterministic Effects • Childhood Cancer is a Stochastic Effect

  4. 70 8-15 Weeks 60 16-25 weeks 50 40 Severe Mental Retardation (%) 30 20 10 0 0 0.1 0.2 0.3 0.5 1.0 1.5 Fetal Dose (Gy) BEIR V Figure 6-1 All Gestational Ages

  5. BEIR V Figure 6-1

  6. BEIR V Figure 6-1

  7. Teratogenesis • Mental Retardation is the Greatest Effect • 0.4% per Rem • Decrease in IQ • 0.3 Units per Rem • Risk is Greatest at 8-15 Weeks • Threshold May Exists at 20-40 Rem

  8. Childhood Cancer • 2.2 per 1,000 (0-15 years) • Relative Risk: 1.4 per Rem • Absolute Risk: 0.06% per Rem (1 Cancer per 1700 children) • Controversial ICRP 84 page 11, 2000

  9. Risks of Pregnancy Chromosomal Abnormalities Viral Infections Growth Retardation Developmental Abnormalities 0 10 20 30 Cases per 1,000 Births

  10. Occupational Exposure During Pregnancy • 0.5 Rem During Entire Pregnancy • 0.05 Rem/Month Once Pregnancy Declared NCRP Report 91, 1987

  11. Pregnancy Testing • Given That The Risk is Small With Fetal Doses in the Few 100 mRem Range, Written Attestation Should Suffice • For Fetal Doses > 1 Rem, a Pregnancy Test Would be Prudent • Pregnancy Tests Are Not Perfect

  12. Mutagenesis Somatic vs Germ Cells

  13. Mutagenesis • 38,000 Parents • 75,000 Births • No Significant Differences in: Infant Mortality Child Mortality Leukemia Sex Ratio Still Births Birth Weights Congenital Abnormalities

  14. Mutagenesis Rare Electrophorectic Variants Exposed Three Probable Mutations in 667,404 Loci Control Three Probable Mutations in 466,881 Loci No Significant Difference

  15. Mutagenesis • Not Demonstrated in Humans • Abundant Evidence in Plants and Animals at High Doses

  16. Genetic Effects 0.15 All Down’s 0.1 Probability 0.05 0 10 20 30 40 50 Maternal Age NEJM 328:114-120, 1993

  17. Conclusions About Mutagenesis • Immeasurable Risk • Pregnancy Should Only be Delayed If It is Expected That the Health of the Mother Will Improve With Time

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