Keywords |
| Nutrient intake, Micronutrients, Longitudinal study, Birth Weight |
Introduction |
| Nutrition is an important health determinant
that can affect the course of pregnancy and its
outcomes. Optimal nutrient intake during
pregnancy is reflected not only in the
improved health of the mother ,but also in the
improved health of the infant[1]. Maternal
diets during pregnancy need to provide energy
and nutrients for the mother as well as for fetal
growth[2]. Poor maternal nutrition during
pregnancy, particularly during the third
trimester, is a major cause of low birth weight
in developing countries[3]. |
| Trace elements are well known to play an
important role in the maintenance of health.
Alterations in maternal-fetal disposition of
some essential trace elements could be a
potential health risk for mother as well as the
fetus[4]. Pregnancy is associated with
increased demand of all the nutrients like
calcium, iron, zinc, copper, and other
micronutrients. Deficiency of any of these
could affect pregnancy, delivery and outcome
of pregnancy[5].Calcium, iron, zinc, and
copper are essential elements required for the
normal growth and development of the
fetus[6]. |
| The role of calcium in intermediary
metabolism and skeletal development in prenatal
and post natal periods have been
established[7]. Calcium plays an important
role in muscle contraction and regulation of
water balance in cells. |
| Iron is an important micronutrient and is
necessary for hemoglobin synthesis and
several other important functions in the body.
Iron deficiency can result not only in reduced
oxygen carrying capacity due to lowered
hemoglobin levels, but can also affect
immunity and growth and development. More
than half the women of reproductive age in
developing countries are anemic, primarily due to iron deficiency as a result of poor diets
and increased requirements [8]. During
pregnancy, iron needs are usually very high to
meet the requirements for the fetus, placenta,
and maternal red cell expansion. Worldwide,
poor pregnancy outcome has been most
commonly associated with anemia caused by
low plasma levels of iron [9]. |
| Inadequate zinc during the prenatal period has
been particularly linked with low birth weight
[10]. Zinc is required for cellular division and
differentiation, and is an essential nutrient for
normal embryogenesis[11]. |
| Copper is an essential trace element for
enzyme systems, such as the catalase,
superoxide dismutase and cytochrome oxidase
systems, and its deficiency can lead to a
variety of nutritional and vascular
disorders[4]. In human adults, severe copper
deficiency is relatively rare, whereas signs of
moderate copper deficiency were observed in
human infants under a variety of
conditions[12]. |
| The micronutrient profile in maternal body
will influence the normal growth and
development of the fetus in the womb. In the
present study, energy and protein intake, some
mineral intake of pregnant women during
pregnancy, maternal and cord blood levels of
calcium, iron, zinc, and copper were
determined to assess the relationship between
these parameters in pregnant mothers and
birth weight of their neonates. |
Material and Methods |
Selection of area, hospitals and subjects |
| Khoy, a city of Western Azarbayjan province
located in North West of Iran, was selected for
research work, as it is the home town of the
investigator. Seven urban health centers was selected. In the present study a total of 450
healthy pregnant women, aged between 18-40
years, attending in public health centers for
their routine prenatal care were selected as
subjects of present study in different social
economic status. From 450 subjects 162
pregnant women were voluntary for giving
blood sample to analyze the microelements in
serum. All subjects were invited by the head
midwife of the center to take part in this
longitudinal Study. The inclusive criteria were
age group (16 to 40 years) and who
continuously visited for health care during the
three trimesters of pregnancy in selected urban
health care centers areas of Khoy city. The
pregnant women with diabetes mellitus and
cardio vascular disease (CVD), multiple
pregnancies, mothers with placenta previa and
placenta abruptia were excluded from this
study. |
| Since the investigator had registered for Ph.D
in University of Mysore, the study was
approved by the Human Ethical Committee of
the University of Mysore and Urmia Medical
University (home town of investigator) as all
the health centers and hospitals in Khoy city
are affiliated to Urmia Medical University.
Written consent letter from all of subjects was
obtained and they accepted to be the subjects
to continue until the birth of the babies. The
study was carried out in the year 2009 to
2010. The required information about various
aspects proposed to study was provided by
questionnaires. |
Selection and Description of the Tools Used
for the Study |
- Questionnaire: |
| A Questionnaire is a tool or device for
securing answers to a set of questions, by
respondent who fills in the Questionnaire. The
Questionnaire method was selected for the present study, as it is frequently used method
of data collection [13]. In the present study,
questionnaire was selected to collect the
maternal family back ground and nutrition
status of pregnant women. |
- Diet survey and Nutrient Intake: |
| Dietary assessment gives reliable information
on dietary intake[14]. The dietary assessment
of pregnant women was done at the end of
first, second and third trimester, three times
during pregnancy, and food intakes were
obtained using 24-hour dietary recall method.
Probing questions were used to help the
subjects to remember different meals and
drinks consumed on previous day, using
standard cups and measures. Probing
questions were used to help the subjects to
remember all foods and drinks consumed on
previous day. Questions were extended to
methods of food preparation, portion sizes, as
well as to approximate sizes of meals.
Standard cups were used to measure the
quantity of intake of the cooked food [15] The
information about the quantity of raw material
(raw quantity) taken for cooking as well as the
cooked food by the subject was recorded in
terms of household measures/number/kg to
find out the quantum of raw food intake. From
the information provided, the cooked and raw
amount of foods consumed by each subject
was then calculated. The mean intake of
different nutrients consumed was then
computed for a day the help of ready recknor
to calculate nutritive value. The ready recknor
was prepared by the investigator using Iranian
food preparation and the nutritive value of
Iranian national food composition[16].
Nutrient adequacy of energy, protein,
calcium, iron, zinc and copper was calculated,
using the ready recknor with reference to
Iranian recommendation[17]. |
- Anthropometric Measurements |
| Anthropometry provides a simple, reliable and
low-cost method of assessing maternal
nutrition status which can be universally
applied at the primary care was selected.
Maternal anthropometry indicates the risk of
intrauterine growth retardation and low birth
weight[18].Body measurements, namely
height and weight, were measured by the
investigator using standard methodology as
described by Jelliffee [19]. The measurements
were made on the participants wearing a
minimum amount of clothing by using digital
weighing balance with a sensitivity of 100 g.
Height was measured in cm using a locally
made anthrop-meter. The pregnant women
were asked to maintain an upright and erect
posture with her feet together and the back of
her heels touching the pole of the anthropmeter,
and the horizontal headpiece was
lowered onto the women’s head. Body Mass
Index: Body mass index in early first trimester
in initial visit when pregnant women refer to
health center for submitting the positive
garvindex test results and apply for having
prenatal care visit was calculated by using the
formula: weight (kg)/ height (m)2 [20]. Birth
weight of newborns were taken within 24
hours after birth, using standard
procedure[21]. A beam balance with an
accuracy of 50 g was employed for weighing
the infants. Infants were weighed with
minimum clothing while the baby was restful. |
Biochemical Analysis |
| Venous blood specimens were collected from
participating pregnant women during each of
the three trimesters were collected in metalfree
plain tubes .Plain tubes were centrifuged
(1100 g) for 15 min 2at 3500 rpm and the
serum was separated and kept in trace
elements-free tubes and stored at ˗40°C until
analysis. Maternal serum levels of zinc, copper, and iron were measured by an
inductively couple plasma mass spectrometer
(ICP/MS). |
Processing of the data and statistical analysis |
| The data collected was subjected to statistical
tests utilizing the SPSS-16.0 version (SPSS,
Chicago, IL, USA). Suitable tests using
Student “t” test, ANOVAs one way, Binary
regression carried out to interpret the results. |
Results |
Family Background of Pregnant Women |
| Details of all selected pregnant women are
presented in Table 1. The mean age of
pregnant women was 26.1±5.8 years and the
age range was 18-40 years. Majority (41%) of
pregnant women were in age group 26-36
years, followed by the age group 20-26 years
(36%). Majority of subjects (55%) had high
school and diploma levels of education. Based
on what the subjects and their family declared,
the total income of a majority of them was
Rials 3-5 million per month. The percentage
of subjects with income less than Rials 3
(million/month) and above Rials 5
million/month were 27 and 25 respectivel.
(See Table 1) |
Anthropometric Measurements of Pregnant
Women during Pregnancy |
| Anthropometric measurements, namely,
height, weight, body mass index and upper
mid arm at first, second and third trimester of
pregnancy are given in Table 2. Our findings
showed significant differences among weight,
body mass index and upper mid arm circumference according to different
trimesters. (See Table 2) |
Energy and Nutrient of Pregnant Women
during Pregnancy |
| Energy and nutrient intakes per day of the
subjects during the three trimesters are
presented in Table3.The mean energy nutrient
intake per day of the subjects in the first
trimester were significantly lower than in
second and third trimester. Mean energy and
nutrient intake by pregnant women in third
trimester were slightly and not significantly
lower than second trimester. It is clear from
the Table 3, that in the first trimester of
pregnancy energy and protein intake was
inadequate. Energy and protein intakes during
second and third trimester were almost
adequate. Calcium, iron and zinc intakes
during first, second and third trimesters were
inadequate. Iron intake in dietary was
inadequate but after including the iron
supplements it was adequate. (See Table3) |
Profile of Serum Calcium, Iron, Zinc and
Copper during Three Trimesters |
| The profile of selected biochemical
parameters, namely, calcium, iron, zinc and
copper in the serum of the pregnant women
during the three trimesters of pregnancy is
given in Table 4. Our findings showed that
there was observable significant difference at
5% level as shown by one way ANOVA post
hoc Bonferroni test during the three trimesters
of pregnancy (See Table 4) |
| The measurements of serum calcium during
the three trimesters of pregnancy showed a
slightly decrease in serum calcium during
second trimester of pregnancy but the mean
serum calcium levels between the first and third trimester were the same (8.9mg/dl). (See
Table 4) |
| As it is clear from the Table 4 there was
noticeable significant difference in iron and
zinc levels during three trimesters of
pregnancy. In comparison with the values in
the first trimester, serum iron and zinc
concentration kept decrease in the third
trimester. |
| The mean levels of copper increased with the
progression of pregnancy and there was
significant difference at 5% level in copper
levels was shown in first, second and third
trimester. |
Birth Weight of Neonates |
| The mean birth weight of neonates were
3275±552 gram. Birth weight was classified
according to W.H.O classification into two
categories namely NBW (>2500g) and LBW
(<2500g) . Our findings showed a majority
(89%) of them had normal birth weight and
11% of them were considered as low birth
weight |
Maternal Energy and Nutrient Intake in
Third Trimester vs. Birth Weight |
| It was interesting to analyze the dietary intake
of energy and nutrient in different levels
intake in pregnant women with reference to
variations in birth weight of neonates. The
data was subjected to one-way ANOVA and
the findings are presented in Table 5. |
| It is clear from the Table 5, with higher intake
of energy resulted in heavier neonates, it
means pregnant women who consumed < 75%
RDA with mean intake 1794±54 kcal/day
gave birth to neonates with 2.6 kg, while |
| pregnant women with ≥100%RDA (2698±107
kcal/day) of energy gave birth to neonates
with 3.6 kg. Significant difference in neonatal
birth weight (400-600gr) was absurd with
increasing almost 374-530 kcal/day energy
intakes by subjects. |
| Similarly with increasing protein intake by the
subjects, the birth weight of corresponding
neonates increased. Pregnant women with
protein intake of <75% RDA with mean
intake 38.7±4.7g/day gave birth to neonates
with 2.5 kg, while pregnant women with
higher intake of protein ≥100%RDA
(72.8±7.4g) gave birth to neonates with 3.4
kg. In the other word with increasing 16 -18g
protein intake by pregnant women, birth
weight of neonates increased 300-600 gram.
(See Table 5) |
| It is evident from the Table 5, that the
pregnant women who consumed calcium less
than <75% RDA (693±207 mg/day) gave birth
to lighter neonates with 3.0 kg (still in normal
weight range), while the pregnant women with
≥ 100%RDA (1298±84mg/day) calcium
consumption gave birth to heavier babies
(3.5kg). |
| The pregnant women with iron intake in
dietary <75% RDA (16.1±3 mg/day) gave
birth to neonates with 2.9 kg, while the
pregnant women with higher intake of iron
(≥100% RDA or 31.5±1 mg/day) gave birth to
neonates with heavier neonates (3.6 kg). |
| As shown in the Table 5 pregnant women who
consumed zinc <75% RDA (9.9±1.3 mg/day),
gave birth to neonates 2.9 kg in compared
with women who consumed ≥100% RDA
(15.9±0.2 mg/day) gave birth to heavier
neonates (3.5 kg). Copper consumption had no
significant influence on the birth weight of the
babies. |
| 3.7). Maternal Serum Calcium, Iron, Zinc and
Copper Levels in Third Trimester vs. Birth
Weight of Neonates |
| It was important to analyze the results of
different categories of serum calcium, iron,
zinc and copper levels of pregnant women
with reference to variations in birth weight of
neonates. The data was subjected to one-way
ANOVA and the findings are presented in
Table 6. It is clear from the Table, Pregnant
women with more than 1200 μg/dl, 80 μg/dl
serum levels of calcium and iron, gave birth to
neonates with heavier birth weight 3.5 and 3.6
respectively; whereas mothers with serum
levels of calcium and iron less than 900 μg/dl
and 60μg/dl gave birth to babies with lighter
birth weight 2.9 and 2.8 respectively (p<0.05).
(See Table 6) |
| It is clear from Table 7, pregnant women with
more than 70μg/dl serum levels of zinc, gave
birth to neonates with heavier birth weight 3.5,
whereas mothers with serum levels of zinc
less than 60 μg/dl gave birth to babies with
lighter birth weight 2.9 (p<0.05). |
| In the present study the association between
maternal copper levels and birth weight was
not significant. |
| It is evident from the study that the various
levels of nutritional attributes influence the
birth weight of infants. Therefore, it is
interesting to find out whether the low birth
weight and normal birth weight infants have
similar or different maternal nutritional
attributes. In order to obtain an answer for this
question, the data on birth weights of neonates
classified as Normal and Low Birth Weight
and the corresponding maternal nutritional
status were illustrated in Table 7. As Table
illustrates, the pregnant women who gave birth to LBW babies had significantly lower
consumption of energy, protein, calcium, iron
and zinc than those who gave birth to neonates
with low birth weight. It is clear from the
Table 7. Pregnant women who gave birth to
low birth weight had lower levels of calcium,
iron and zinc levels than the pregnant women
who gave birth to normal neonates. (See Table
7) |
Predicting Factors for Birth Weight |
| The nutrient intakes such as energy, protein,
calcium, iron, zinc, the maternal serum
micronutrients levels such as calcium, iron,
zinc affected birth weight of neonates. It was
interesting to find out among these
parameters, which factors can be considered
as major predictable factors for birth weight of
neonates. Therefore the binary logistic
regression was carried out to find out the
possible factors associated with birth weight
(results are presented in Table 8). The findings
showed calcium, protein, iron, energy intake,
could be considered as ″prediction factors″ for
birth weight of neonates. (See Table 8) |
Discussion |
| The percentage of energy, protein and copper
were adequate (85%, 80% , 86%.) in the
present study while the consumption of
calcium, iron and zinc were inadequate
(51%,56%,50%) according the Recommended
Daily Allowance [22]. In this study iron
consumption in dietary was inadequate with
reference to RDA, but it was adequate when
iron supplementation is added. The actual
consumption of supplementary nutrients was
not monitored and this is one of the limitations
of the study. . Similar studies in India [23];
Spain [24], USA; [25], and Iran [26], [27], showed that energy and protein intakes were
adequate while calcium, iron and zinc intakes
were inadequate. |
| The mean serum calcium during the first,
second and third trimesters were almost the
same. The similar results were reported in
Hungary [28], and in Argentina [29]. In
pregnancy, the very high circulatory
concentrations of estrogens and progesterone
alter the concentration of many substances
including calcium in the maternal blood [30].
Studies of calcium homeostasis responses
during pregnancy have shown increase in both
intestinal calcium absorption and urinary
calcium excretion during pregnancy and
increase rate of bone turnover during
pregnancy [31, 32]. |
| Our findings showed that there was noticeable
significant difference in iron levels during
three trimesters Similar variation in serum
iron during pregnancy was shown in South
Korea [33], and India [34]. There was
significant difference in zinc and copper levels
but not magnesium levels during the three
trimesters of pregnancy. Regarding the zinc
variations during pregnancy period, our results
indicated that zinc levels of subjects kept
decreasing gradually from first trimester to
third trimester. Similar results were shown in
other studies in Turkey [35]; Spain;[36]; and
in USA [37]. The decline may be explained by
a disproportionate increase in plasma volume,
as well as the maternal–fetal transfer. The
other reasons possibly be decrease in zinc
binding [38], or low dietary bioavailability
[39], or very high amounts of copper or iron in
the diet that compete with zinc at absorption
sites [40]. |
| Mean serum copper levels during the three
trimesters of pregnancy in our results show
that copper levels rise significantly with
increasing gestational periods. Similar results
were shown in studies in Spain [36]; Turkey
[35], and in China [41]. The increase of copper with the progression of pregnancy
could be partly related to synthesis of
ceruloplasmin, a major copper binding
protein, as a result of elevated levels of
maternal estrogen. Another reason may be the
decreased biliary copper excretion induced by
hormonal changes, typical during pregnancy
[42] |
| Results of the current study show as energy
and protein intake of pregnant women are
increased the birth weight of neonates also
increased. Other groups of investigators in
Canada[43], India [44], Iran[45] have reported
comparable results with regard to protein and
energy intake and birth weight. |
| It is interesting to observe that with increase in
the amount of calcium, iron and zinc intake,
the mean birth weight increased. Similar
results were observed in other countries
namely USA [46]; UK [47]; South Africa
[48]; Iran[49]. |
| Copper consumption had no significant
influence on the birth weight of the babies.
Similar results were reported in other
countries like USA[50]; UK [51]; and South
Africa [52]. |
| Regarding the association between maternal
serum calcium, iron and zinc and birth weight,
our finding are close agreement with studies in
California [53]; UK [48]; Korea [54]; and Iran
[55] , which reported there were significant
association between maternal calcium, iron
and zinc with birth weight of neonates. The
mechanisms that operates by which poor iron
status may affect birth weight and preterm
births remains poorly understood [56]. A few
tested hypotheses showed that iron is
necessary for hemoglobin synthesis and
several other important functions in body. Iron
deficiency can result not only in reduced
oxygen carrying capacity due to lowered
hemoglobin levels, but can also affect
immunity and growth and of fetus [57]. |
| Zinc is an important nutrient during pregnancy
and plays a critical role in normal growth and
development, cellular integrity and several
biochemical functions. Zinc is a component of
many enzymes, it takes part in normal cell
division, and has a role in carbohydrate, lipid,
protein, and nucleic acid synthesis. Therefore
an impairment in these presses can retard fetal
growth and result in LBW of the infant [37]. |
| In the present study the association between
maternal copper levels and birth weight was
not significant, which is agreement with
results of other studies in Turkey [58] and
Kuwait [59] |
| To distinguish the relationship between
maternal nutrition status in low birth weight
and normal birth weight of neonates, analysis
of data was tasted in third trimester of
pregnancy. As Table 7 illustrates, the pregnant
women who gave birth to LBW babies had
significantly lower consumption of energy,
protein, calcium, iron and zinc than those who
gave birth to neonates with low birth weight.
It is clear from the Table7 pregnant women
who gave birth to low birth weight had low
levels of calcium, iron and zinc levels than the
pregnant women who gave birth to normal
neonates. Similar results have been reported in
Turkey [60] and Iran [61]. |
| The findings showed calcium, protein, iron,
energy intake, could be considered as
″prediction factors″ for birth weight of
neonates. In agreement with our results other
studies in Canada [62]; California [53]; and
India [63] reported the same results. |
| It may be concluded that for the study that
maternal energy, protein, calcium, iron and
zinc intake along with higher maternal serum
calcium, iron and zinc influenced birth weight
of the neonates. The findings of the study
indicated that total iron intake calcium,
protein, iron and energy intake as a predictor
factors for birth weight. It may be recommended from the present study that the
government and nongovernment agencies
should focus on the effective implementation
of program to improve the nutrient intake of
pregnant women to optimize their health
which will elevate the pregnancy outcome. |
Acknowledgments |
| We appreciate the administrators of hospitals,
and laboratory; Dr.Frootani and Mr. Samadi,
for their support and cooperation. Cooperation
of the staff in the selected health care centers
is highly acknowledged. We are sincerely
indebted to all the participants who made this
study possible. |
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