Original ResearchPattern and determinants of birth weight in Oman
Introduction
Birth weight (BW) is a key predictor of the health, survival and development of a new born baby. It is not only associated with the high mortality risk during childhood, but also highly associated with health, physical, emotional, psychological and scholastic development and well-being in childhood and adulthood.1, 2, 3, 4, 5, 6, 7, 8, 9 Low birth weight (LBW) – defined by the World Health Organization (WHO) as weight at birth of less than 2500 g (i.e. 2.5 kg or 5.5 pounds)10 – is associated with increased risk of numerous adverse health outcomes in childhood and adulthood.11, 12
Previous studies have shown that LBW babies are 20 times more likely to die than normal weight (≥2500 g) babies.1, 2 As LBW is largely preventable, it provides a target for intervention to improve the child health and survival.6 LBW has been selected as an important indicator for monitoring the achievement of major health goals during the 2002 World Summit for Children.13 It is also one of the targets of the Millennium Development Goals (MDGs). The target to reduce at least one-third of the incidence of LBW by 2015 was established by the international community as a move to achieve the first goal of the MDGs for eradicating extreme poverty and hunger.14 LBW is thus given high priority by the national governments and the international community.
United Nations Children's Funds (UNICEF) reported that there are more than 20 million infants worldwide, representing 15% of all births, are born with LBW in 2011.15 According to a joint study of UNICEF and WHO in 2004 about 96% of LBW newborns are seen in developing countries and the level of LBW in developing countries (17%) is more than double the level in developed regions (7%).12
BW is a composite of foetal growth and length of gestation, each of which has different contributors.16 Many factors effect BW that are related to the infant, the mother, the physical environment or the genetics.12 The risk factors of LBW include, among others, maternal factors such as: maternal health and her risky health behaviours, insufficient antenatal care, psychosocial stress, low body mass index, poor nutrition, diseases, diet and lifestyle during pregnancy as well as socio-economic and demographic characteristics. Some other risk factors of LBW are sex and birth order of the baby, genetic factors and environmental pollution.17 Although several causal associations are well established, there are mediating and etiological factors whose effects on the different components of LBW are still under investigation. Although the pattern of risk factors for adverse BW may be similar among populations, the relative contribution of each factor may vary from one setting to another.12, 18, 19 It is, therefore, important to identify population-specific factors affecting BW so that appropriate policy intervention can be formulated for further improvement of child health and survival.
The Sultanate of Oman is one of the Arabian Gulf Countries. The country was under poverty and isolation until 1970. However, by the late 1980s, Oman was transformed into a modern state, with all the modern facilities and infrastructures, under the dynamic leadership of the present ruler His Majesty Sultan Qaboos Bin Said who ascended to power in 1970. Economically, Oman is now classified as a high-income country with a per capita Gross Domestic Product (GDP) of more than US$20,000 in 2013.20 The standard of living and health status have improved enormously since 1970. The country has a well-organized universal free health care system assuring universal access to health care services for all of its citizens which is widely recognized and acclaimed by various international organizations, including the World Health Organization.21, 22 As a result almost all the health indicators witnessed dramatic improvements over the past four decades and several diseases have been eliminated from the country. Oman has also made impressive gains in the achievement of key MDGs.23 Despite all these improvements in health status, a recent concern is raised about some of the childhood health indicators, particularly the LBW and infant and under-five mortality for their unchanging or increasing trends as indicated by the recent health statistics of the Ministry of Health (MOH) in Oman.24
Data from MOH demonstrate that the infant and under-five mortality rates in Oman remain almost unchanged at a rate of around 10 and 12 per 1000 live births, respectively, since 2005, despite continued efforts for improving child health and survival. On the other hand, LBW shows increasing trends since 1980. LBW rate was about 4% in 1980, doubled (8.1%) in 2000, and had further increased to 10.2% in 2013.25 It seems that improved medical technologies greatly improved the foetal survival chances since the middle of last century, but didn't directly help much to reduce the incidence of LBW.24
In Oman, LBW has appeared as the second leading cause of morbidity among newborns and a leading cause of early neonatal mortality (death before seven days of life) and the third leading cause of mortality among infants (death before one year of age).25 Thus, LBW can be seen as a real challenge for improving child health and survival in Oman. As BW is one of the important biomarker of health, survival and future development of newborn babies, it is important to identify the risk factors for LBW, so that appropriate measures can be taken for the improvement of health and survival of infants. This study provides an overview of the pattern of BW and identify the factors affecting BW and the risk factors of LBW in Oman using data from a population based nationally representative health survey. The findings of the study may have important policy implications for the improvement of newborn health and survival.
Section snippets
The data
The data for this study came from the 2000 Oman National Health Survey (ONHS) which was conducted by the MOH with the collaboration of UN organizations such as UNFPA and UNICEF, WHO and the UN Statistics Division. The details of the 2000 ONHS may be seen in Al- Riyami et al.26 Only married women under 50 years of age who were Omani nationals were included. The survey covered a nationally-representative sample of 2037 married women from 2013 randomly selected households. The sample of households
Characteristics of sample children
Table 1 presents the distribution of 977 sampled infants considered in this study across their selected background characteristics. This information is important for interpretation of the study results and examination of any cause–effect relationship among the study variables. More than one-third of the infants (34%) were born to mothers aged less than 25 years. About one-fifth (22%) of the infants were born to mothers with advanced age of 35 years. The mean age of mothers was about 28 years.
Discussion
The objective of this study was to examine the pattern and determinants of LBW in Oman using a population-based national-level health survey data. The mean BW was found to be 3.09 (SD 0.51 kg) kg, which is at least 360 g less than the new-born babies of the United States of America (USA) on whom WHO's reference standard is based.10 The birth weight of 95% full-term healthy babies of the USA fall between 2454 and 4442 g with a mean of 3.45 kg.10, 16 The mean BW was found to be significantly
Acknowledgements
The authors would like to thank the Ministry of Health of Oman, especially the directorate of research and studies, for providing the raw data file for conducting this study. The views expressed herein are solely those of the authors and do not necessarily reflect the views of any institution or organization.
Ethical approval
No ethical approval was needed for this study because it was based on secondary analysis of the data obtained from the 2000 Oman National Health Survey (ONHS) which was conducted by the
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