The decline of postnatal mortality from gastrointestinal anomalies with age.

It has been previously shown that mortality from congenital anomalies decreases with the first power of age with the exception of "gastrointestinal anomalies". On the other hand, mortality declines with the second power of age in the category "certain conditions originating in the perinatal period". According to the theory of congenital individual risks, the dying out of more impaired individuals causes these two types of mortality decline. Mortality decline with the first power of age is the most frequent type of mortality decline after birth. This evidence is explained as a consequence of the rule: the higher the individual risk of death, the less frequent the individual risk is at the moment of birth. If all defects (and all individual risks) appear with the same frequency and selection does not occur (e.g. this could be assumed for certain conditions originating in the perinatal period) then mortality declines with the square of age. Here, it is shown that mortality from "gastrointestinal anomalies" (ICD9 codes: 750 and 751) decreases with the second power of age in all five countries within the age interval 1-10 years. This is a consequence of evidence that these defects do not affect vitals important during pregnancy and selection is not significant. These findings demonstrate that the selection of higher individual risks proceeds during pregnancy rather than during previous generations.