A Demographic and social study of fertility in rural New Guinea

Abstract

The commencement of demographic transition with rapid mortality decline and changing fertility patterns has been studied prospectively for 20 years among over 5000 persons in Buka and New Ireland—two pre-industrial societies of New Guinea. The demographic study has been complemented by a detailed social study of fertility variables in three societies. At the commencement of the study the New Ireland society had a high level of primary and secondary sterility of gonorrhoeal origin which disappeared among the younger women after mass penicillin therapy. The mean age at marriage is no longer immediately post-menarchal; the mean age of mother at birth of first child varied between 18·7 and 20·6 years; and the mean age of cessation of reproduction approached 44 years. The three societies each show differing degrees of demographic transition with social patterns in one hardly changed by culture contact through to occasional voluntary use of introduced contraceptive techniques. The most important changes in fertility variables over the 20-year survey were the decrease in duration of post-partum abstinence from intercourse, the increase in continuity of cohabitation in marriage and other pronatal effects. The demographic assessment of Buka showed age specific fertility rates for 1962–67 of over 300 per each 5-year age group between the ages of 20 and 39 with total fertility reaching a maximum of 8680 and with consequent changes in family size. The mean birth interval for births fell from 3·15 years for persons with first births between 1947 and 1953 to 2·13 years where the first birth was after 1961. There are several levels of reproduction with a mean birth interval for women for the most productive group of 2·00 years. The current mean interval for births of 2·16 years is consistent with a maximum biological level of reproduction for a society using breast feeding as the sole significant negative factor affecting fertility. The associated rapid mortality decline and improved health of the community were due to the control of malaria and available rural health services as part of authoritarian health measures. Fertility decline consistent with transition theory would require community participation in child spacing to re-establish the traditional family size of three to four surviving children. This would entail the introduction of biochemical and mechanical contraception to fill the role previously taken by post-partum abstinence from intercourse and high infant mortality.