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A Prospective Study of Hemoglobin Status, Micronutrient Serum Levels and
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Nutrient Intake of Iranian Pregnant Women during Pregnancy and Their
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Relation to Birth Weight of the Neonates
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Abstract: A prospective study was conducted in Iran to investigate the hemoglobin status,
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micronutrient serum levels and nutrient intake of Iranian pregnant women and their relation to
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birth weight. Nutrient intake was computed based on 24 hour recall method. During the three
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trimesters of pregnancy, blood specimens were collected from healthy pregnant women aged 16-
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40 years. Maternal serum levels of micronutrients were determined by an inductively couple
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plasma mass spectrometer (ICP/MS) and haemoglobin was assessed by Cyanomethemoglobin.
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The mean age of studied pregnant women was 26 ± 5years, and the mean birth weight of
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neonates was 3.3 ± 0.4 kg. The 11% of neonates were considered as low birth weight. The results
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showed that majority (41%) of pregnant women were in age group 26-36 years. The mean
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hemoglobin during the second trimester was significantly lower than the mean hemoglobin in the
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first and the third trimesters of pregnancy. The majority of the anemic women belonged to mild
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category during pregnancy. Regarding micronutrients, results indicate that iron levels decreased
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significantly from first to second trimester and significantly increased in third trimester. Serum
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zinc levels of subjects significantly decreased gradually during the first, second and third
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trimester. Serum copper levels increased significantly with increasing the gestational period.
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Calcium and magnesium serum levels during three trimesters were constant. Maternal
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hemoglobin levels, calcium, iron and zinc serum levels were associated with birth weight of
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neonates. Energy, protein, calcium, zinc and iron intakes in the third trimester were significantly
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associated with birth weight of neonates. The findings showed that calcium, protein, iron and
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energy intake of pregnant women could be considered as primary ″predictor factors″ for birth
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weight of neonates.
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Key Words: Hemoglobin Status, Micronutrient Serum Levels, Nutrient Intake, Pregnant
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Women, Birth Weight of the Neonates
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1) Introduction
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Every year more than 20 million infants are born with low birth weight worldwide. About 3.6
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million infants die during the neonatal period (Black, Cousens et al. 2010). Two thirds of these
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deaths occur in southern Asia and sub-Saharan Africa. More than one third of child deaths are
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thought to be attributable to maternal and child under nutrition (Black, Allen et al. 2008).
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Deficiencies in micronutrients such as iron, calcium, zinc, copper and magnesium are highly
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prevalent and may occur concurrently among pregnant wome(Graham, Knez et al. 2012) It is
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estimated that 50% of pregnant women in the developing countries, 18% from the industrialized
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countries, and up to 80% in South Asia have iron deficiency anemia (Tapiero, Gate et al. 2001).
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Iron deficiency and consequent anemia during pregnancy could be associated with severe
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complications like increased risks of maternal mortality and morbidity, premature delivery, and
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low birth weight(Malee 2008). The role of calcium in intermediary metabolism and skeletal
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development in prenatal and post natal periods has been established(Demment, Young et al.
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2003). In humans, inadequate zinc nutrition has been associated with an increased risk of
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pregnancy complications, including intrauterine growth retardation, prolonged labor, abnormal
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deliveries, vaginal bleeding, and a variety of intrauterine malformations (Tamura, Goldenberg et
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al. 2000). Copper is an essential trace element for enzyme systems and its deficiency can lead to
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a variety of nutritional and vascular disorders (ZEYREK, SORAN et al. 2009).
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Pregnancy is a critical period during which the diet of the pregnant woman reflects not only
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on her own health, but on the health of the fetus as well. Nutritional adequacy both in quantity
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and quality during this time is important for the physical and mental development of the infant
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and later on, of the child(Demment, Young et al. 2003).
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The micronutrient profile in maternal body will influence the normal growth and
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development of the fetus in the uterus. The present descriptive study was planned with the
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objectives of the maternal hemoglobin and levels of calcium, iron, zinc, copper, and magnesium
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of pregnant women and assessing the association between these parameters in pregnant mothers
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and the outcome of newborns.
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2) Material and Methods
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2.1) Selection of area, hospitals and subjects
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Khoy, a city located in Iran, was selected for research work. A total of 450 healthy pregnant
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women, aged between 16-40 years, attending in public health centers for their routine prenatal care
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were selected as subjects of present study in different social economic status. The inclusive criteria
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were age group (16 to 40 years) and who continuously visited for health care during the three
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trimesters of pregnancy in selected urban health care centers. The pregnant women with diabetes
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mellitus and cardio vascular disease (CVD), multiple pregnancies, mothers with placenta previa and
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placenta abruptia were excluded from this study. Written consent letter from all of subjects was
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obtained and they accepted to be the subjects to continue until the birth of the babies. The study was
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carried out in the year 2009 to 2010. The required information about various aspects proposed to
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study was provided by questionnaires.
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2.2) Diet survey and Nutrient Intake:
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The dietary assessment of pregnant women was done, and food intakes were obtained using
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24-hour dietary recall method. Probing questions were used to help the subjects to remember
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different meals and drinks consumed on previous day, using standard cups and measures. Nutrient
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adequacy of energy, protein, calcium, iron, zinc and copper was calculated (Thimmayamma and
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Pravathi 1996).
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2.3) Body Measurements
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Birth weight of newborns was taken within 24 hours after birth, using standard
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procedure(Jelliffee 1966) A beam balance with an accuracy of 50 g was employed for weighing the
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infants. Infants were weighed with minimum clothing while the baby was restful.
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2.4) Biochemical Analysis
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Venous blood specimens were collected from participating pregnant women during each of the three
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trimesters was collected in metal free plain tubes. The serum was separated and kept in trace
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elements-free tubes and stored at ˗40°C until analysis. Haemoglobin and other blood parameters are
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considered as good indicators of nutritional status (Bamji, Rao et al. 1996). The selected methods for
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haemoglobin assessment were Cyanomethemoglobin (W.H.O/ UNICEF/ 46 UNO, 1998). Inductively
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Couple Plasma Mass Spectrometer (ICP/MS) (Shariati, Yamini et al. 2009) was selected for serum
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calcium, iron, zinc, copper and magnesium analysis.
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2.5) Processing of the Data and Statistical Analysis
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The data collected was subjected to statistical tests utilizing the SPSS-16.0 version (SPSS,
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Chicago, IL, USA). Suitable tests ANOVAs one way, Binary regression carried out to interpret the
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results.
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3) Results:
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3.1) Family Background of Pregnant Women
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The mean age of pregnant women was 26.1±5.8 years and the age range was 18-40 years.
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Majority (41%) of pregnant women was in the age group of 26-36 years. Most of the subjects
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(55%) had high school and diploma levels of education. Eighty-seven percent of subjects were
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home makers (Table 1).
3.2) Hemoglobin Levels during Three Trimesters of Pregnancy: The average hemoglobin
content during the three trimesters of pregnancy is presented in Table 2.
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It is clear from Table 2 that there was significant difference in the mean hemoglobin
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levels during the three trimesters. The mean hemoglobin during the second trimester was
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significantly lower (p<0.05) than the mean hemoglobin in the first and the third trimesters of
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pregnancy.
As shown in Table 3, 77%, 71% and 79% of the subjects had normal hemoglobin during
the three trimesters of pregnancy. The majority of the anemic women belonged to mild category
21%, 26% and 20% in the first, the second and the third trimester respectively (Table
3)(WHO/UNICEF/UNO.IDA 1998)
3.3). Profile of Serum Calcium, Iron, Zinc, Copper and Magnesium during Three Trimesters
of Pregnancy: The profile of serum calcium, iron, zinc, copper and magnesium of the pregnant
women during the three trimesters of pregnancy is given in Table 4.
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The mean serum calcium during the first, second and third trimesters were similar and no
change was observed (8.96±0.48, 8.86±0.47 and 8.91±0.42 mg/dl).
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Our findings showed that there was a significant difference at 5% level in iron levels
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during the three trimesters. In comparison with the values in the first trimester, serum iron
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concentration kept decreasing in the third trimester.
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There was significant difference at 5% level in zinc and copper but not magnesium levels during
the three trimesters of pregnancy. The mean serum magnesium during the first, the second and
the third trimesters was almost the same (2.10±0.21, 2.08±0.28, 2.09±0.29).
3.4) Birth Weight and Maternal Nutritional Status: Different levels of dietary intake of
energy, protein, calcium, iron, zinc, copper and magnesium by pregnant women with reference to
variations in birth weight of neonates showed that pregnant women (in third trimester) who
consumed 60-79 % of RDA per day gave birth to neonates with LBW (2.6 kg), while the
pregnant women with 80-99% of RDA gave birth to neonates with NBW (3.3kg) and with
>100% RDA of energy per day gave birth to neonates with 3.6 kg. According to our results
increasing of RDA has a positive association with increase birth weight. Regarding association
between protein and other nutrients intake with birth weight the results are presented in the Table 5.
3.5) Birth Weight and Hemoglobin Levels: The levels of hemoglobin in the present study were
categorized into different levels on the basis of WHO classification. According to the
classification of the World Health Organization, pregnant women who had hemoglobin levels
less than 11.0 g/dL on the first and the third trimesters were categorized as anemic women.
Women with anemia during the third trimester of pregnancy and who had hemoglobin levels 910.9g/dl, 7-8.9 g/dl and <7g/dl were classified as having mild, moderate and severe anemia
respectively (WHO/UNICEF/UNO.IDA 1998).
As shown in the Table 5 pregnant women with hemoglobin less than 9 g/dl, and who are
considered as anemic gave birth to neonates with birth weight of 2.6 kg, while pregnant women
with higher hemoglobin level (>11 g/dl), who were considered as normal, gave birth to heavier
and normal babies (3.5 kg). Our findings showed that as the hemoglobin level of pregnant
women increased, the birth weight of the neonates also increased. (Table 6)
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3.6). Birth Weight and Maternal Serum Calcium and Iron Levels: It was important to
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analyze the results of different categories of serum calcium, iron, zinc, copper and magnesium
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levels of pregnant women with reference to variations in birth weight of neonates. The findings
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are presented in Table 7. It is clear from the Table that pregnant women with more than >9.1
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µg/dl calcium and 80 µg/dl iron serum levels, gave birth to neonates with heavier birth weight of
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3.6 and 3.7 respectively, whereas, mothers with serum levels of calcium and iron ≤8.7µg/dl and
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<67µg/dl gave birth to babies with lighter birth weight 3.1kg and 2.9kg respectively (p<0.05). As
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shown in the Table, the birth of neonates increased with increase of maternal serum calcium and
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iron levels. Regarding zinc levels our findings showed that pregnant women with more than
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70µg/dl serum levels of zinc, gave birth to neonates with heavier birth weight 3.5, whereas,
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mothers with serum levels of zinc less than 60 µg/dl gave birth to babies with lighter birth
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weight- 3kg (p<0.05). In the present study the association between maternal copper and
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magnesium levels and birth weight were not significant. Table 7.
3.7) Information on Neonates
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3.7.1) Anthropometric Measurements: Anthropometric measurements of the neonates, namely,
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weight, height, head, chest and upper mid arm circumferences showed a mean of 3.2 kg, 49.4
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cm, 34.7 cm, 33.1 cm and 10.8 cm respectively as shown in Table 8. The male neonates were
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heavier, taller and their head and chest circumferences were higher than females (Table 8).
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3.7.2) Prevalence of Low Birth Weight (<2500g) Neonates: Birth weight was classified
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according to W.H.O classification into two categories, namely, low birth weight (< 2500g) and
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normal birth weight (≥2500 g). Our findings were classified and are presented in Table 8. A
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majority (89%) of neonates had normal birth weight and only 11% of them were considered as
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low birth weight. Table 9
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3.8) Prediction of Maternal Factors with Reference to Birth Weight of Neonates
Binary logistic regression was carried out to find the predictor factors when all the
maternal nutritional attributes are considered together with reference to birth weight (Table 10).
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4) Discussion:
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The reduction that was observed in the mean hemoglobin during the second trimester of
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pregnancy is related to the plasma expansion. Regarding the prevalence of the anemia similar
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results were conducted in Iran (Mirzaei, Eftekhari et al. 2010).
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The mean serum calcium during the first, second and third trimesters were constant.
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Similar results was reported in Argentina (Zeni, Soler et al. 2003). On the contrary the results of
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the study in China (Liu, Yang et al. 2010) showed a decline in the maternal serum calcium in the
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second trimester of pregnancy in comparison to the first and the third trimester. The mean serum
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calcium level presented in the current study in all three trimesters was higher than that in a study
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reported in China (6.8mg/dl) (Liu, Yang et al. 2010). Other studies conducted in Thailand
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(Sukonpan and Phupong 2005) and Ethiopia (Kassu, Yabutani et al. 2008) reported that the range
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of calcium was higher than the mean of calcium level in the current study. Optimum level and
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any sort of changes in the level of serum calcium play a vital role in the health and wellbeing of
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the mother as well as of the neonate. The very high circulatory concentrations of estrogen and
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progesterone alter the concentration of many substances including calcium in the maternal blood
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during pregnancy (Mayne 1996). Studies of calcium homeostasis responses during pregnancy
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have shown increase in both intestinal calcium absorption and urinary calcium excretion during
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pregnancy and increased rate of bone turnover during pregnancy(Prentice 2000).
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In comparison with the values in the first trimester, serum iron concentration in our study
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kept decreasing in the third trimester. This reflects the fact that the iron stores in the pregnant
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body gradually fell during pregnancy. Similar variation in serum iron during pregnancy was
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shown in South Korea (Lee, Kang et al. 2002). A comparison of the mean serum iron in the
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current research with the findings of a study in Amman (Awadallah, Abu-Elteen et al. 2004)
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showed that the mean serum iron was lower than the mean serum iron in the current study for all
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trimesters.
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The mean serum levels of zinc in a study conducted in Amman (Awadallah, Abu-Elteen
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et al. 2004) during the first, the second and the third trimester of pregnancy were similar with the
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result of the current study. A comparison between the mean serum zinc during the three
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trimesters of pregnancy in the current study with a study in China (Liu, Yang et al. 2010) showed
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that the mean serum zinc levels was higher in China than in the current findings. Similar results
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regarding the zinc variations during the pregnancy period were shown in other studies in China
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(Liu, Yang et al. 2010) and Turkey (Ilhan and Simsek 2002). The decline in zinc levels is
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explained by a disproportionate increase in plasma volume, as well as the maternal–fetal transfer.
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The other reason is a decrease in zinc binding (Tamura, Goldenberg et al. 2000), or low dietary
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bioavailability (Tuttle 1983), or very high amounts of copper or iron in the diet that compete
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with zinc at absorption sites (Sheldon, Aspillaga et al. 1985).
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Our results show that copper levels rose significantly with increasing gestational periods.
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Similar results were shown in studies in Turkey (Ilhan and Simsek 2002) and China (Liu, Yang
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et al. 2010). The increase of copper with the progression of pregnancy is partly related to
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synthesis of ceruloplasmin, a major copper binding protein, as a result of elevated levels of
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maternal estrogen. Another reason is the decreased biliary copper excretion induced by hormonal
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changes, typically during pregnancy (O’Brien, Zavaleta et al. 1999).
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Regarding the mean serum magnesium during pregnancy the similar results was reported
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in Argentina.(Zeni, Soler et al. 2003). In the study that was carried out in India (Pathak, Kapoor
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et al. 2003) among pregnant women, the findings showed that the mean serum magnesium was
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lower than the current findings, while the mean serum magnesium in normal pregnant women
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that was reported in Thailand (Punthumapol and Kittichotpanich 2008) was similar to the present
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study. As shown in our study, the blood magnesium levels slightly decreased (<0.05) in the
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second trimester and increased in the third trimester. Generally, the hypomagnesemia is
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associated with hemodilution, renal clearance during pregnancy, and consumption of minerals by
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the growing fetus (Williams and Galerneau 2002). Besides, the blood magnesium levels are
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partly dominated by estrogen (Dale and Sinpson 1992).
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Results of the current study showed that as energy and protein intake of pregnant women
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increased the birth weight of neonates also increased. Other groups of investigators in India
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(Rao, Aggarwal et al. 2007) and elsewhere in Iran (Houshiar-Rad, Omidvar et al. 1998) have
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reported comparable results with regard to protein and energy intake and birth weight. However,
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contradicting this result, a study conducted in Oman (Bawadi H 2010) has not found a significant
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relationship between the intake of energy and protein and the birth weight.
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Similar results with consumption of the calcium and iron by pregnant women were
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observed and reported in others countries, namely, Saudi Arabia (Al-Shoshan 2007); South
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Africa (Osendarp, West et al. 2003) and Iran (Sabour, Hossein-Nezhad et al. 2006).
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Similar results was shown in the USA (Neggers, Goldenberg et al. 1997) which indicated
that higher consumption of zinc resulted in heavier neonates.
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Results from other studies which have been conducted in other countries, namely, the
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Saudi Arbia (Al-Shoshan 2007) and South Africa (Osendarp, West et al. 2003) noted that, in
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agreement with the present study there is no significant relationship between copper and
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magnesium intake and birth weight of neonates.
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Our findings showed that as the hemoglobin level of pregnant women increased, the birth
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weight of the neonates also increased. Other study in India (Malhotra, Sharma et al. 2002) and
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Iran (Yazdani, Tadbiri et al. 2004) are in agreement with the current study which indicated the
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importance of normal hemoglobin level ( Hb>11g/dl) on pregnancy outcome.
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Regarding the association between birth weight and maternal serum calcium and iron levels, our
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finding are in agreement with the studies in Iran (Hadipour, Norimah et al. 2010) and Korea(Lee,
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Kim et al. 2006), which reported that there was significant association between birth weight of
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neonates and maternal calcium and iron levels. Zinc is an important nutrient during pregnancy
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and plays a critical role in normal growth and development, cellular integrity and several
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biochemical functions. If a pregnant woman has zinc deficiency, the fetus will suffer from zinc
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deficiency during fetal development. Therefore, an impairment in these processes can retard fetal
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growth and result in LBW of the infant (King 2000).
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In agreement with the results of other studies in Turkey (Ozdemir, Gulturk et al. 2007);
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and Kuwait (Al-Saleh, Nandakumaran et al. 2004) our results showed no significant differences
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between copper and magnesium levels during pregnancy and birth weight of the neonates.
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Eleven percent of neonates were considered as low birth weight. Similar results were reported in
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Iran (Veghari 2009)(11.1%). The prevalence of low birth weight in India (Rao, Kumar Aggarwal
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et al. 2007), (24.3%) was higher and in Japan(Takimoto, Yokoyama et al. 2005), (8.3%) was
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lower than that in the present study.
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5) Conclusion and Suggestion:
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It may be concluded that maternal nutrient intake, hemoglobin levels and serum calcium, iron
and zinc influenced birth weight of the neonates.
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The findings of the Binary logistic regression test showed that hemoglobin levels,
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calcium intake, protein intake, iron intake and energy intake of women could be considered as
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″prediction factors″ for birth weight of neonates. These studies would be enable the appropriate
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intervention strategies to be developed, implemented, and evaluated. Such efforts will require the
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collaboration and commitment of government agencies, health care providers, nutritionists,
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research institutions, and the community. Our findings may help the government and non
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government agencies to concentrate on efficient performance education workshops on prenatal
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care and maternal nutritional status, considering that appropriate gestational weight gain has a
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close connection to birth weight of the neonates.
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Acknowledgments: We are indebted to the administrators of hospitals, and laboratory; Dr. Mohammad
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Reza Frootani and Mr. Samadi, for their support and cooperation. Cooperation of the staff in the selected
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health care centers is highly acknowledged. We are sincerely indebted to all the participants who made
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this study possible.
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