Part 1 Disorders of development: weighing the evidence for environmental causes: Criteria for Teratogenesis: I. Time order, strength, consistency; Criteria for Teratogenesis: II. Specificity; Criteria for Teratogensis: III. Coherence; Part 2 Conception and early gestation: Conception and reproductive loss: Probabilities; Developmental abnormalities: Frequency measures; Developmental abnormalities: Frequencies observed; Karyotypes at miscarriage: Variations and regularities; Environmental factors, miscarriage and karyotypes; The recurrence of miscarriage and chromosomal aberrations; Part 3 Later gestation: The separation of entities: Preterm delivery, low birth weight and maturity; Preterm delivery: I. Indices and enumeration; Preterm delivery: II. Risk factors; Fetal growth and birth weight: I. Indices and risks; Fetal growth and birth weight: II. Norms and thresholds; The family factor in birth weight; Maternity and birth in less developed countries; Part 4 Age and parity: Aging and reproduction: I. Conception to birth; Ageing and reproduction: II. Trisomy; Pregnancy number problems of analysis; Part 5 The physical environment, reproduction and surveillance: Surveillance of reproductive outcomes: I. Keeping watch; Surveillance of reproductive outcomes: II. Following leads.