Methods: Six hundred patients at Milad hospital in 2011 were evaluated in this study. The second and third trimester hemoglobin levels were measured, in addition to investigating the relationship between the maternal hemoglobin level and the incidence rate of low birth weight and preterm delivery. Finally, the relation between the second and third trimester hemoglobin levels and education, job, history of abortion, and the use of calcium, folic acid, iron, and multivitamin pills was evaluated as well.

Results: The results indicated that the second trimester maternal hemoglobin levels were high in patients with preterm delivery and low birth weight. The relative risk of preterm delivery in the second trimester of pregnancy was 1.89 times higher in the high hemoglobin group compared to the normal hemoglobin group (CI = 1.15-3.01), and it was 1.16 times higher in the third trimester. Based on the results, the relative risk of low birth weight in the high hemoglobin group was 2.7 times the normal one (CI = 1.15-5.01), and it was 1.03 higher in the third trimester.

Conclusions: In general, high hemoglobin, especially in the second trimester, is associated with a higher risk of subsequent preterm delivery and low birth weight. Hence, it is recommended that women with high hemoglobin levels in their second trimester should be check up timely to reduce the undesirable effects of pregnancy.