Study of the records of 5,878 pregnancies made it possible to construct a life table (mortality table, attrition table) for the fetal period of human existence, analogous to the life tables in general use for the postnatal period. Birth is an event in life, not the beginning of it. For each week of gestation completed by the fetus, the table states the probability that the fetus will be born alive and will survive the neonatal period.