Gestational length within the sibships

Abstract

This note follows a previous one in this Review in which we analyse the variations of birth weight in the sibs. Now we study the variation of gestational length. The reproductive histories of 1065 women are collected by a match of the records of the deliveries in the hospital of Padua between the years 1963-77. We analyse the frequencies of different types of sequences of the differences between the gestational length in the sibs. The sequences with an increased dynamics are not the more frequent, on the contrary the more frequent one are those with an oscillating dynamics.