Disproportion in the falling birth rate.
Since 1962 there has been a disproportionately greater fall in the number of small (less than 1000 g) live births than total live births: this has applied to Sheffield and to England and Wales but more to the former. This may have affected falling neonatal mortality rates.
D001723:Birth Rate; D004739:England; D005260:Female; D005313:Fetal Death / Q000453:epidemiology; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D009026:Mortality; D011247:Pregnancy; D014852:Wales