Asia-Pacific Population Journal - Volume 17, Issue 1, 2002

The 1999 population and housing census of Viet Nam estimated the population to be 76 million people (CCSC, 1999). According to the 1994 intercensal survey, the total fertility rate (TFR) was 3.1 children per woman of reproductive age in 1993 (GSO, 1995). The estimate from the 1999 census was 2.3 children per woman in 1999. These estimates suggest that fertility has been falling rapidly in Viet Nam.

The main reason for reinvestigating the possible linkage between consanguinity and offspring mortality emerged as a result of the gross disagreement among researchers on this subject. For the purpose of this study, consanguinity is defmed as marriage between relatives who share at least one common and detectable ancestor. There is no common consensus in the field of human genetics or demographic research regarding the biological impact of parental consanguinity on the health of their offspring. However, in this regard it is possible to recognize three broad schools of thought. Adherents of the first school consider that there is an overwhelming possibility of consanguineous parents having an unhealthy child. According to this school of thought, marriage between close relatives is genetically critical, because closely related individuals have a higher probability of carrying the same alleles than less closely related individuals. Consequently, an inbred child (the progeny of a consanguineous couple) will more frequently be homozygous for various alleles than the offspring of unrelated persons (Whittinghill, 1965). To the extent that homozygosity for genes is deleterious, consanguineous marriage is deleterious (Sutton, 1965). In this respect, the genetic load of deleterious recessive genes, usually known as the lethal equivalent, would cause death if present in homozygous combination (Cavalli-Sforza and Bodmer, 1971). A number of studies on this subject have focused on an increased level of morbidity (Bemiss, 1858; Rao and others, 1977; Ansari and Sinha, 1978) and mortality (Farah and Preston, 1982; Bundey and Alam, 1993; Bittles, 1994) among the offspring of consanguineous parents. Survey results from a few other sources have also identified a linkage between consanguinity and spontaneous abortion (Neel and Schul, 1962; Al-Awadi and others, 1986) and intrauterine loss (Saheb and others, 1981).

Population ageing has been a topic of considerable interest during the last decade (Knodel, 1999), more so in the developed regions of the world than in the less developed regions. This is so because the process of population ageing has been much slower until recent times in the less developed regions.

Internal migration is an integral part of the development process. It is influenced by development (such as the building of roads, economic activities and employment opportunities in certain areas) and it influences development (destination areas gain in skills and capital while areas of origin lose out) (Chandra and Chandra, 1998:60). There are relationships between and among migration, urbanization and socio-economic development. According to Skeldon (1992:45): “At a very simple level, there is a clear relationship between economic development and demographic variables. The most developed countries have the highest levels of urbanization … and they have low fertility and low rates of infant mortality. The least developed countries, however, have low levels of urbanization …”.