Maternal anemia during pregnancy is an independent risk factor for low birthweight and preterm delivery

Abstract

Objective: The present study was designed to investigate the outcome of pregnancy and delivery in patients with anemia.

Methods: A retrospective population-based study comparing all singleton pregnancies of patients with and without anemia was performed. Deliveries occurred during the years 1988-2002 in the Soroka University Medical Center. Maternal anemia was defined as hemoglobin concentration lower than 10 g/dl during pregnancy. Patients with hemoglobinopathies such as thalassemia were excluded from the analysis. Multiple logistic regression models were performed to control for confounders.

Results: During the study period there were 153,396 deliveries, of which 13,204 (8.6%) occurred in patients with anemia. In a multivariable analysis, the following conditions were significantly associated with maternal anemia: placental abruption, placenta previa, labor induction, previous cesarean section (CS), non-vertex presentation and Bedouin ethnicity. Higher rates of preterm deliveries (<37 weeks gestation) and low birthweight (<2500 g) were found among patients with anemia as compared to the non-anemic women (10.7% versus 9.0%, p < 0.001 and 10.5% versus 9.4%, p < 0.001; respectively). Higher rates of CS were found among anemic women (20.4% versus 10.3%; p < 0.001). The significant association between anemia and low birthweight persisted after adjusting for gender, ethnicity and gestational age, using a multivariable analysis (OR = 1.1; 95% CI 1.0-1.2, p = 0.02). Two multivariable logistic regression models, with preterm delivery (<37 weeks gestation) and low birthweight (<2500 g) as the outcome variables, were constructed in order to control for possible confounders such as ethnicity, maternal age, placental problems, mode of delivery and non-vertex presentation. Maternal anemia was an independent risk factor for both, preterm delivery (OR = 1.2; 95% CI 1.1-1.2, p < 0.001) and low birthweight (OR = 1.1; 95% CI 1.1-1.2, p = 0.001).

Conclusion: Maternal anemia influences birthweight and preterm delivery, but in our population, is not associated with adverse perinatal outcome.