CHAPTER ONE
INTRODUCTION
1.0     BACKGROUND TO THE STUDY
In 1948, the first World Health Assembly adopted an international definition of prematurity as birth weight of 2.5kilograms or less (UN (2004)). It was however discovered that in developing countries the use of this standard resulted in an unusually high proportion of `premature' babies most of who were not born prematurely (Yilgwanet.al. ,2004). The World Health Organization (WHO) in 1994 then conducted a study on eighteen different countries at different stages of development. This revealed that babies could be classified into three main groups based on their birth weight and gestational age: Small for gestational age, appropriate for age, large for age. Low birth weight was then defined as those babies weighing less than 2.5kilograms within twenty four hours of birth. This group of babies can either be small for age or appropriate for age and they are usually at high risk of dying in their first twenty eight days of life from factors like hypoglycaemia, sepsis, respiratory distress, prematurity etc. In Nigeria, neonatal death (death of an infant in the first twenty eight days of live) contributes about 25% of the total infant mortality with prematurity and low birth weight being the main contributor to these high neonatal deaths(Grange, 2006).
A reduction of at least one-third in the proportion of infants with low birth weight is one of the seven major goals for the current decade of the “A World Fit for Children” programme of the United Nations. Moreover, nutritional deprivation — the major determinant of low birth weight — is a clear obstacle to the attainment of many of the Millennium Development Goals. Monitoring improvements in low birth weight is thus being given high priority within the UN system, as well as by national governments and the international nutrition community.
Although the significance and interpretation of low birth weight has recently been debated, most experts agree that weight at birth is an indicator of a new born's chances for survival, growth, long-term health and psychosocial development. Babies whose birth weight is low as a result of undernourishment face a greatly increased risk of death during their first months and years of life (Bale et.al.,2003, UN, 2000, Allen & Gillespie, 2001). The evidence also suggests that those children who do survive may be more likely to experience health problems throughout their lives; these include impaired cognitive development, as well as diabetes and coronary heart disease in adulthood (Bhargavaet.al., 2004, Barker, 2003). Low birth weight in developing countries occurs primarily because of poor maternal health and nutrition. A variety of socioeconomic, medical, and psychosocial factors are known to increase the risk of low birth weight, but prevention programs aimed at primarily high-risk subgroups have been largely ineffective.
In addition, diseases such as diarrhoea, malaria and respiratory infections, which are common in many developing countries, can significantly impair foetal growth when women become infected during pregnancy (Bale et.al.2003, UN 2000). In Nigeria just like in many developing countries, low birth weight is a significant contributor to the overall infant mortality rate and a major factor in the high neonatal mortality rate currently seen.
This research work however seeks to check for the dependence of birth weight on some factors which may affect it such as parity, maternal height, maternal age, gestation period, and gestation weight using the Chi-Square test of independence, regression analysis to see possible statistical relationships if any exists among the variables in question.