Starting, spacing and stopping in the reproductive histories of outer Hebridean families

Maternal ages at the first maternity (starting), at the last maternity (stopping) and the lengths of intervals between maternities (spacing) have been studied in the Outer Hebridean islands of Harris and Barra for births between the years of 1855 and 1990, a period during which a considerable 'fertility transition' occurred. There was a tendency in each island for increases with time in the ages at starting among less-fecund women (although after 1936 starting ages declined), and highly significant heterogeneity of covariance: adjusted means dependent on the total numbers of maternities experienced. The same result was seen for the ages at stopping. Lengths of reproductive 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 1956-1975, possibly due to the papal encyclical Humanae Vitae. Intervals between marriage and first maternity and between successive maternities were studied by hazard function survival analysis. The marriage first birth interval remained very constant, unaffected by total maternities. The father's occupation and the mother's age at first maternity showed no significant relationships. In Barra there was a weak negative relationship with the date of the marriage. For intervals between maternities in both islands, total maternities and the death of a previous infant were associated with shorter, and birth order with longer intervals. In Harris, there were tendencies For intervals to be consistently long or short in families, and for the age of the mother and date at first maternity to be negatively related to the length of the interval. In Barra, a previous multiple birth was Followed by a longer interval. The date of the previous maternity, father's occupation, maternal age at the previous maternity, the sex of the previous child, and the duration of the marriage appeared to have no influence on maternity intervals Evidence for an effect of economic deprivation during the 19th century on the variables considered was equivocal. During the 20th century, it is suggested that economic depression during the inter-war years, the spread of contraception, and improvements in health care may have acted 'synergistically to produce the lower ages of childbearing and the shortening of maternity intervals and reproductive lives.