Starting, spacing and stopping in the reproductive histories of Outer Herbidean families

Maternal ages at the first maternity (starting), at the last maternity (sto pping) and the lengths of intervals between maternities (spacing) have been studied in the Outer Hebridean islands of Harris and Barra for births betw een the years of 1855 and 1990, a period during which a considerable 'ferti lity transition' occurred. There was a tendency in each island for increase s with time in the ages at starting among less-fecund women (although after 1936 starting ages declined), and highly significant heterogeneity of cova riance: adjusted means dependent on the total numbers of maternities experi enced. The same result was seen for the ages at stopping. Lengths of reprod uctive life (the difference between ages at starting and stopping) rose to 1876-1895, and then fell, apart from a short-lived rise in Barra during 195 6-1975, possibly due to the papal encyclical Humanae Vitae. Intervals betwe en marriage and first maternity and between successive maternities were stu died by hazard function survival analysis. The marriage first birth interva l remained very constant, unaffected by total maternities. The father's occ upation and the mother's age at first maternity showed no significant relat ionships. In Barra there was a weak negative relationship with the date of the marriage. For intervals between maternities in both islands, total mate rnities and the death of a previous infant were associated with shorter, an d birth order with longer intervals. In Harris, there were tendencies For i ntervals to be consistently long or short in families, and for the age of t he mother and date at first maternity to be negatively related to the lengt h of the interval. In Barra, a previous multiple birth was Followed by a lo nger interval. The date of the previous maternity, father's occupation, mat ernal age at the previous maternity, the sex of the previous child, and the duration of the marriage appeared to have no influence on maternity interv als Evidence for an effect of economic deprivation during the 19th century on the variables considered was equivocal. During the 20th century, it is s uggested that economic depression during the inter-war years, the spread of contraception, and improvements in health care may have acted 'synergistic ally to produce the lower ages of childbearing and the shortening of matern ity intervals and reproductive lives.