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Abstract: Natural sources contribute a large fraction of the radiation exposure of the general public. Under the linear no-threshold hypothesis risk decreases in proportion to decreasing dose without a threshold. We use recent estimates of doses to the red bone marrow to calculate the number and proportion of cases of leukemia in England induced by natural radiation. We calculate that about 5% of cases of leukemia, excluding chronic lymphocytic leukemia, up to the age of 80 years are induced by this background radiation. In young people up to the age of 25 years the attributable fraction is about 15%, substantially lower than a previous estimate. [Copyright &y& Elsevier]

Objective: Failure of fetal growth during pregnancy, and preterm birth, are the major causes of stillbirth and early neonatal death. The objective of the study was to determine the association between maternal hemoglobin concentration during pregnancy and perinatal mortality. Study design: The design was prospective, using data on-222,614 first singleton pregnancies in the St Mary's Maternity Information System database in the Northwest Thames region of London. Results: The association of perinatal mortality with maternal hemoglobin at first antenatal check was not statistically significant (P > .10), but a statistically significant (P < .001) U-shaped pattern was found with lowest recorded maternal hemoglobin concentration. Both early neonatal mortality and stillbirth rates were statistically significantly (P < .005) associated with lowest maternal hemoglobin concentration. The relationship of lowest hemoglobin with early neonatal mortality was largely mediated by the effect of preterm birth, and that between lowest hemoglobin and stillbirth by fetal growth restriction. The lowest perinatal mortality was associated with a lowest recorded maternal hemoglobin concentration of between 9–11 g/dL. Conclusion: There is an optimal range of lowest hemoglobin concentration in pregnancy, and on either side of this perinatal mortality is increased. The effect of lowest hemoglobin is largely mediated through associations with preterm birth and fetal growth restriction. [ABSTRACT FROM AUTHOR]

Background: Evidence exists that normal gestational length varies with ethnicity. This UK-based study compares gestational length amongst a cohort of white European, Black and Asian women., Methods: The cohort comprised 122 415 nulliparous women with singleton live fetuses at the time of spontaneous labour, giving birth in the former North West Thames Health Region, London, UK., Results: The median gestational age at delivery was 39 weeks in Blacks and Asians and 40 weeks in white Europeans. Black women with normal body mass index (BMI) (18.5-24.9 kg/m(2)) had increased odds of preterm delivery (odds ratio [OR] = 1.33, 95% CI: 1.15, 1.56, adjusted for deprivation and BMI) compared with white Europeans. The OR of preterm delivery was also increased in Asians compared with white Europeans (OR = 1.45, 95% CI: 1.33, 1.56, adjusted for single unsupported status and smoking). Meconium stained amniotic fluid, which is a sign of fetal maturity, was statistically significantly more frequent in preterm Black and Asian infants and term Black infants compared with white European infants., Conclusions: This research suggests that normal gestational length is shorter in Black and Asian women compared with white European women and that fetal maturation may occur earlier.