Seasonal variation of birth weight distribution in Morogoro, Tanzania
Kinabo, J.
East African Medical Journal 70(12): 752-755
1993
ISSN/ISBN: 0012-835X PMID: 8026346 Document Number: 408876
Low birth weight (LBW) has been defined as a birth weight below 2500 g. Birth weight is increasingly being used as an indicator of socioeconomic development, with comparative studies of different ethnic groups under various socioeconomic conditions having found birth weight to be largely affected by the socioeconomic setting and little by ethnic grouping. The occurrence of LBW is a reflection of maternal stress during pregnancy. Maternal nutrition is one of the most important factors influencing pregnancy and the state of the newborn baby. Studies have shown maternal weight gain to be the most important predictor of infant birth weight. In most developing countries, however, the outcome of pregnancy is determined by the availability of food which also determines the level of energy intake and energy expenditure; both are highly dependent upon the rainfall pattern in a given area. This paper reports findings from a study exploring the influence of seasonal variation upon the distribution of birth weight in the town of Morogoro, Tanzania. The author examined data for 19,783 full-term singleton babies to determine the effect of seasonal variation on birth weight. Mean birth weight was found to be 3020 +or- 502 g, and 2354 of the babies were of LBW. Mean birth weight was lowest during the rainy season and highest during the dry season, a period immediately after harvest. Birth weight responded rapidly to changing conditions of food intake and energy expenditure rather than the generally expected slow rise or fall in birth weight in response to gradual changes in conditions. The study also found that birth weight does not only respond to prevailing conditions during the last few months of pregnancy, but also to existing conditions just prior to delivery. This latter finding has significant implications for food supplementation programs for pregnant women.