International Journal of

Introduction
Anemia is a major health problem that affects 25% to 50% of the population of the world and approximately 50% of pregnant women (1). Anemia in pregnancy is associated with increased rates of maternal and perinatal mortality, premature delivery, low birth weight and other adverse outcomes (2). The probable predisposing factors for anemia in pregnant women include parity, low socioeconomic status and substance abuse among others (3-5). Anemia in non-pregnant women is defined as hemoglobin less than 12 g/dl. The   cutoff   suggested   by  United  States   Center for  Diseases Control described anemia as a  hemoglobin less than 11g/dl in the first and third trimester and less than 10.5 g/dl in the second trimester (6).
     The World Health Organization (WHO) defined anemia as hemoglobin concentration below 11g/dl in pregnancy (7). The WHO estimates the prevalence of anemia 17.5%-40.5 % in female of reproductive age. This report does not include pregnant women in Iran (8). The present study was conducted to investigate the prevalence and risk factors for anemia in pregnant women in Kerman, Iran.
 
Materials and methods
     This cross sectional study was conducted between January 2005 and December 2007 on pregnant women referring to University Teaching Hospital of Kerman. The study protocol was approved by the ethics committee at Kerman University of Medical Sciences. Informed consent was obtained from each participant before enrollment. Inclusion criteria were as follows; a single fetus without history of chronic hypertension, diabetes, thyroid, cardiac diseases and systemic lupus erythematosis. Women with hemoglobinopathies such as thalassemia were excluded.
     Hemoglobin concentration was recruited from perinatal medical records, and cases were studied in first (0-14 wks), second (15-28 wks) and third (29-42 wks) trimester. Gestational age was determined on the basis of the information on menstrual history and early ultrasound examination.
     A checklist was used to record information about age, parity, iron use, history of cigarette smoking and opium consumption in the parturient. The other variables including obstetrics complications such as: placenta previa, placental abruption, preeclampsia, birth weight, and gestational age at delivery and route of delivery were recorded.
 
Statistical analysis
     Results were reported as mean ± standard deviation (SD) or median. Categorical variables were compared using the Chi-square or Fisher’s exact test. Independent sample t-test was used to compare quantitative variables (such as hemoglobin level and age) between groups. For comparison    of    anemia    between     age    and
educational  level  Kruskal-wallis test was used.
For statistical analysis, the statistical software SPSS version 13.0 for Windows (SPSS Inc., Chicago, IL) was used. All p values were 2 tailed and statistical significant was defined by p≤0.05.

Results
     Generally, of 2223 pregnancies, the median age was 26.82±5.84 (12-48) years. Median age of anemic women was 27.15±6.25 years and in non-anemic group it was 26.8±5.82 years (p=0.55). Generally, 104 (4.7%) of the study population were anemic (Hg<11gr/dl), out of which 4.8% had severe anemia (Hg<7g/dl), 15.4% had moderate anemia (Hg: 7-8.9g/dl) and 79.8% had mild anemia (Hg: 9-10.9g/dl). The frequency of anemia was 5%, 3.4% and 5.7% in the first, second and third trimester, respectively. 1154 (45.5%) were multipara and it was associated with lower hemoglobin concentration during the second/third trimester of pregnancy (p=0.03 and p<0.001, respectively) (Table I).
     Twenty–one (1%) of all patients were smokers and anemia was observed in 19% of smokers vs. 4.6% of non-smokers but no significant differences were found in hemoglobin concentration in different trimesters (Table I). Eighty (3.8%) of women were opium users, that 12.5% of them were anemic (p=0.003) and opium users were associated witch lower hemoglobin concentration in third trimester (p=0.03) (Table I).
     Generally, 2017 (91%) of patients had used iron supplements during pregnancy. In iron supplements users 4% and in others 11.9% were anemic (p<0.001). There was no significant association between anemia with maternal education and threatened abortion (Table II).
          Median gestational age at delivery was 37.82±2.5 (26-43.8) weeks and 516 of births (23.5%) were before 37 weeks. The prevalence of anemia was 5.9% in women with preterm delivery while this was 4.3% in term deliveries (p=0.034).


Table I. Hemoglobin concentration in relation to maternal risk factors for anemia in different trimesters of pregnancy.


Table II. Maternal characteristics and prevalence of anemia.


Discussion
     The prevalence of anemia in this study was 4.7%; it was less than prevalence of anemia that was reported by WHO in non pregnant women in Iran (17.5%-40.5%), but it was similar to Vahidian study (4.8%) (9).
     In Iran, iron and folate supplements are routinely prescribed for pregnant women. Generally, 91% of our patients had used iron supplements during pregnancy. Measured hemoglobin levels could be affected by iron and folate supplements and this may be the cause of lower prevalence of anemia comparing with those reported by WHO (10).
     The prevalence of anemia varies during the course of pregnancy. In this study, we found a 5% prevalence of anemia at the first trimester, 3.4% at the second trimester and 8.7% at the third trimester. In normal pregnancy, the expansion of the plasma volume which precedes the increase in red cell mass, creates a disproportionate expansion of plasma volume (50%) compared with the increase in red cell mass (30%). Therefore, “hemoglobin values start to decline during the early phase of first trimester and reach their nadir near the end of second trimester” (11). The prevalence of anemia observed in this study reflected the change of hemoglobin values during pregnancy.
     Effect of multiparity on anemia is unknown, in this study, there was significant association between anemia and parity while in Adam et al   study, there were no significant association between anemia and parity (12).
     Smoking is a legal and socially tolerated form of substance abuse. The incidence of smoking in the pregnant population has increased in recent decades to between 16.3% and 52%; depending on the characteristic of the patient group, however there is evidence that it is declining in some populations (13-16).
     In our study, 1% of all women were smoker. Anemia was seen in 19% of smokers vs. 4.6% in non-smokers. It was similar to Subramoney et al study, that showed mean hemoglobin levels were significantly lower in smokers (10gr/dl) compared with non smokers (10.46gr/dl) (p<0.001) (17).
     Substance abuse during pregnancy is an increasing problem that is associated with significant maternal and fetal morbidity (18). Substance use during pregnancy ranges from 0.4% to 27% depending on the population surveyed (19). In this study 3.6% of women were opium users that 12.5% of them were anemic (p=0.003). Factors such as poor nutrition, social problems, and poor antenatal attendance are involved in anemia.
     We found preterm delivery in 23% of pregnancies, anemia was observed in 5.9% with preterm delivery vs. 4.3% in term delivery. Several studies, documented sub-optimal fetal outcomes, such as: low birth weight and preterm delivery (20-22). Other investigators however did not find any association between maternal anemia and adverse pregnancy outcome (23).
 
Conclusion
     Based on our study prevalence of anemia was not high. Cigarette smoking, opium consumption, and multiparity were associated with the risk of anemia.
 
Acknowledgement
     The authors would like to thank Farzan Institute for Research and Technology for technical assistance.