Prevalence of Low Birth Weight and Preterm Birth and the Influential Factors in Zanjan, Iran (2014-2016)

Background: The prevalence of low birth weight (LBW) has been estimated at 15.5%, and approximately 15 million preterm births (PTB) occur across the world. These rates have been reported to be 9% and 9.2% in Iran, respectively. Objectives: The present study aimed to assess the prevalence of LBW and PTB and compare their influential factors in Zanjan province, Iran during 2014-2016. Methods: This descriptive-analytical study was conducted on 41,265 neonates (stillbirth and alive) in Zanjan province and suburbs. Data were collected using the registries of the midwives in charge of the maternal and neonatal registry system. Data analysis was performed in Excel and SPSS version 16 using descriptive and analytical tests, including the univariate and multivariate logistic regression models. Results: The prevalence of LBW and PTB was 7.2% and 8.2%, respectively. Odds ratio of LBW was lower with increased parity (OR=0.736; P<0.001) and gestational age (OR=2.570; P<0.001), while it was higher in female neonates (OR=1.324; P<0.001) and infants with congenital malformations (OR=2.570; P=0.001). Odds ratio of PTB was higher with increased abortions (OR=1.206; P<0.001) and in male neonates (OR=1.440; P<0.001), while it was lower with increased birth weight (OR=0.996; P<0.001). Maternal underlying diseases and diabetes reduced the odds ratio of LBW (OR=0.633; P=0.019) and increased the odds ratio of PTB (OR=3.650; P<0.001). Moreover, preeclampsia and eclampsia increased the odds ratio of LBW (OR=3.140; P<0.001) and PTB (OR=1.489; P=0.005). In terms of social factors, maternal education level decreased the odds ratio of LBW (P<0.05). The prevalence of PTB increased by 22.8% in 2015 compared to the previous year (P=0.012). Conclusion: According to the results, congenital malformations, gender, gestational age, birth weight, maternal education level, and maternal underlying diseases were significantly correlated with LBW and PTB. Therefore, improving maternal and neonatal health requires proper planning to control the influential factors in LBW and PTB.