The birth weight of an infant is an important issue, as it plays significant roles in infant/childhood mortality and also has important health implications in overall growth and development of individuals.1 Birth weight has been shown to be an index of intrauterine growth and a reliable predictor of child survival and mental development.23
There are numerous research studies concerned with the factors that determine birth weight.4-10 Factors such as maternal weight gain, smoking, alcohol consumption, gestational age, maternal anthropometry and many other variables have all been the subject of several scientific papers. The World Health Organization defines normal birth weight as 2500 to 4000 grammes. Low birth weight (<2500g) is usually associated with significant infant mortality. 1, 11 Fetal macrosomia (birth weight >4000g)12 has however been shown to have significantly less association with infant mortality in recent years, probably due to medical advances in management of the condition.13
Smoking has been documented to reduce birth weight. It is postulated that the mechanism for this is via tobacco induced loss of appetite, resulting in reduced maternal nutrition and resultant low birth weight.14 Many other socio-biologic factors affecting birth weight include maternal age, maternal education, sex of baby, antenatal care, marital status, socioeconomic status, genetic factors and place of residence 2
The objectives of this study were to determine the factors that influence birth weight and to establish which of these factors can be used to estimate birth weight. The aims were to ascertain the individual effect of each of these factors and their effect as a group. This is an important research question, and findings from the research can be used to inform policy decisions concerning maternal and child health care programmes.
2.1: Study design: A cross sectional study
2.2: Sample description: Data used for this study was routinely collected information about births registered in the United States of America, by the centre for disease control and prevention’s national centre for health statistics. It consists of a selection of information on all births in the state of Wyoming, USA in 2003
The study sample consists of all 6,208 births in the state of Wyoming USA, in 2003. The variables contained in the dataset includes Information on maternal age, race, education, weight gain in pregnancy, number of cigarette smoked daily during pregnancy, number of alcoholic drinks consumed weekly in pregnancy, month of onset of antenatal care, number of prenatal hospital visits and number of previous children, living and dead. Weight gain was defined as the difference between the recorded weight at first visit and the recorded weight at the last visit before delivery.9 Information was also collected on baby’s weight at birth, baby sex, and gestational age. Gestational age was defined as the duration in weeks from the mothers last...