Maternal anemia during pregnancy and small for gestational age: a systematic review and meta-analysis

Objective: Anemia is a major public health and nutritional problem in the world. Studies have reported the relationship between anemia during pregnancy and small for gestational age (SGA). Therefore, the present systematic review and meta-analysis was conducted to determine the relationship between maternal anemia during pregnancy and SGA. Method: This meta-analysis was conducted without time limit until April 2017 based on the PRISMA protocol. Several international databases including Cochrane, Scopus, Web of Science (ISI), Pubmed, Embase, and Google Scholar search engine were searched independently by two researchers. The keywords include: anemia, pregnant women, gestational age, and pregnancy. The relative risk (RR) and 95 confidence interval were estimated regarding to the significance of the I-2 index based on the random effects model. Data were analyzed using Comprehensive Meta-Analysis Software version 2. Results: Ten studies with a sample size including 620 080 pregnant women entered the meta-analysis process. The overall relationship between maternal anemia during pregnancy and SGA was not significant (RR = 1.11 95%CI: 0.99-1.24, p = .074). The relationship between anemia during pregnancy and SGA based on pregnancy trimester showed that maternal anemia was significant in the first trimester, (RR = 1.11 95%CI: 1-1.22, p = .044), but this relationship was not significant in the second trimester (RR = 1.11 95%CI: 0.85-1.18, p = .91). Conclusions: Maternal anemia in the first trimester of pregnancy can be considered as a risk factor for negative pregnancy outcomes (SGA)