Birth weight within the sibships

Abstract

The reproductive histories of 1065 pluriparous women are collected by a match of the records of the deliveries at the hospital of Padua between the years 1963-77. This material is analysed in two stage. In the present note we study the variations of the birth weigh in the sibs; in a future one we will analyse the variations of the gestation length. The variables utilized are the following: difference of birth weigh between the sibs, difference of gestation length, difference of birth order, difference of age of the mother at the deliveries, difference of the sex of the sibs. These variables are introduced in a multiple linear regression model of the birth weight. The partial regression coefficient relative to the birth order is positive. The frequency of the histories in which the weight of successive sibs increased are also examined. It results that this situation is not the most frequent but the histories with an oscillating dynamics are the more numerous