Secular trends in size at birth of Iranian neonates: Meta-analyses of published and unpublished studies

ISSN： 1464-5033

Source： Annals of Human Biology, Vol.40, Iss.1, 2013-01, pp. : 75-82

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Abstract

Context: Secular trend in birth sizes is a well-known indicator of living conditions of a society. Objective: This study conducted meta-analyses estimating the mean birth weight (BW) and birth length (BL) of Iranian neonates born between 1971 and 2010. Methods: Data were collected from published studies through literature searches using Pubmed, Google scholar, Irandoc, Iranmedex, SID, magiran and unpublished studies including theses and projects conducted at the three main Iranian medical universities between 1971-2010. Mean and SD of BW or BL with other relevant data were extracted from eligible studies. Results: Of 266 studies identified, 61 were found to be eligible. The combined BW was 3222 (95% CI = 3093-3351), 3233 (95% CI = 3203-3264) and 3152 grams (95% CI = 3114-3189) in the 1970s, 1990s and 2000s, respectively. The mean decrease of 81 grams in BW during the 2000s was significant compared to the 1990s. The combined BL in the 1970s, 1980s, 1990s and 2000s were 50.3 (95% CI = 49.2-51.4), 49.5 (95% CI = 46.6-52.3), 50.0 (95% CI = 49.7-50.3) and 50.2 cm (95% CI = 49.6-50.8), respectively. No significant changes in BL were observed. Conclusion: This meta-analysis found a negative secular trend in BW of Iranian neonates during 2000s with a rate of ∼ 8.1 g/year.