Iron Deficiency Anemia and Associated Factors During Pregnancy: A Longitudinal Study of Women Attending Antenatal Care Facility in Nigeria

Abstract

Objective

The purpose of this study was to investigate iron deficiency anemia (IDA), its associated factors, and intake of iron/folate supplements among pregnant women in the antenatal care facility of Aminu Kano Teaching Hospital, Kano, Nigeria.

Methods

The study was longitudinally designed, and 112 pregnant women in the second trimester were recruited and followed up through the third trimester. Sociodemographic characteristics, medical/obstetrical history, consumption pattern, and iron indices were assessed using standard methods.

Results

This study showed that 58.0% of the pregnant women investigated have attained a tertiary level of education, and 50.0% were full-time housewives. Among the pregnant women, 56.4% were iron/folate supplement-compliant, and 83.0% and 67.8% were multigravida and multipara, respectively. The study reported that approximately 24.8% of the pregnant women consumed heme iron food sources at least 1 to 3 times daily, while approximately 64.8% did not have a daily intake of at least 1 nonheme iron–rich food source. Iron deficiency anemia prevalence in the second trimester was 10.7%, increasing to 16.5% in the third trimester (P < .05). Similarly, all-cause anemia increased from 37.5% to 65.9% and iron deficiency from 14.3% to 23.5% (P < .05 for both).

Conclusion

Progression from the second to third trimesters was associated with an increased risk of anemia, iron deficiency, and IDA among pregnant women. Pregnant women taking iron/folate supplements had higher iron indices than the noncompliant pregnant women. Consumption of iron-rich foods among pregnant women was low and had little effect on the iron indices estimated, while supplement intake and birth spacing had a significant negative association with anemia, iron deficiency, and IDA.

Introduction

Iron deficiency anemia (IDA) is the most common nutritional disorder, which accounts for approximately one-half of all anemia cases.¹ The disorder involves diminished red blood cell production due to low iron stores in the body caused by inadequate intake, decreased intestinal absorption, increased demand, and chronic blood loss.² Iron is a trace element necessary for most cellular activities associated with the syntheses of hemoglobin, myoglobin, and cytochrome, which makes it a crucial requirement for respiration, mitochondrial function, and energy production.³ Similarly, iron is extremely important during pregnancy owing to rapid cell and tissue development associated with fetal growth.⁴ Since fetal iron requirements take precedence over maternal needs and storage,⁵ adequate iron intake is imperative for both mother and fetus.

Insufficient amount of iron during pregnancy could lead to IDA, and its consequences include negative perinatal outcomes such as intrauterine growth restriction, low birth weight, birth asphyxia, premature labor, postpartum depression, and developmental delay in the baby’s growth.^6,7 Consequently, the World Health Organization (WHO) recommends supplementation with daily oral iron and folic acid as part of antenatal care to decrease the risk of iron deficiency (ID), maternal anemia, and low birth weight.⁸ However, oral iron supplementation is challenged by poor compliance due to gastrointestinal side effects³ and possibly limited knowledge of its impact. Breymann⁹ stated that lack of compliance is a common problem associated with oral iron supplementation, and in Nigeria, only 21% of pregnant women complete the dose of iron tablets during their last pregnancy.¹⁰ Estimates from WHO show that the prevalence of IDA in pregnancy ranges from 14% in developed countries to 56% in low- and middle-income countries.¹¹ The Nigeria Demographic and Health Survey in 2018 reported the prevalence of anemia among pregnant women to be 61%.¹²

Information on IDA and pregnant women is needed to improve the quality of antenatal care accessible to pregnant women in the study area. A study is needed to help strengthen the nutrition information system in the state and the nation at large, as well as contribute to monitoring the achievements made in meeting one of the Global Nutrition Targets (reduction of anemia in women of reproductive age by 50%) by 2025 and Sustainable Development Goals 2 (Target 2.2) and 3 (Target 3.1).

In spite of the high prevalence of IDA during pregnancy in Nigeria, the adverse consequences of its existence are not fully elucidated. There is paucity of data on IDA and its associated factors among pregnant women in Kano, Nigeria. Therefore, the purpose of this study was to investigate changes in iron indices, intake of iron/folate and other supplements, prevalence of ID and anemia, as well as associated factors (sociodemographics, medical/obstetrical history, and dietary pattern) among pregnant women in Kano.

Methods

Ethics

This study was performed in line with the principles of the Declaration of Helsinki. Ethical approval for the study was obtained from the institutional ethical committees of Aminu Kano Teaching Hospital (AKTH), Kano (AKTH/MAC/SUB/12A/P-3/VI/2650), and Ahmadu Bello University, Zaria (ABUCUHSR/2020/015). Informed written and/or verbal consent was sought from each subject before inclusion into the study.

Study Design

This was a longitudinal study to evaluate IDA and its associated factors among pregnant women attending the antenatal clinic AKTH, Kano, Nigeria. Blood samples were collected from consented pregnant women in their second trimester upon confirmation from the ultrasound scanning results. The pregnant women were then followed up, and their blood samples were again collected when they were in the third trimester (12 weeks after recruitment).

Study Area

This study was carried out at AKTH, Kano, Nigeria. Aminu Kano Teaching Hospital is a government tertiary teaching hospital located at 11.9634° N, 8.5504° E, Unguwa Uku, Kano, Nigeria. The core function of this facility is service delivery, teaching, and research. Antenatal and delivery services to pregnant women and other services related to general health care are provided by the Obstetrics and Gynecology Department of the hospital.

Selection Criteria

All pregnant women within the age of 15 to 49 years in their second trimester attending the antenatal clinic, AKTH, at the time of study were recruited. However, pregnant women with medical complications such as diabetes, hypertension, cardiovascular diseases, HIV/AIDS, cancer, and hemoglobinopathies were excluded. Also, pregnant women who refused to give consent were excluded.

Sample Size and Sampling Technique

A sample size of 112 was used, as calculated according to Dobson’s formula: n = t² (p × q/d²) where n = sample size, t = 95% CI (1.96), p = prevalence rate (6.50%) as reported by Nwizu et al¹³, q = 1 − p (1 − 0.065 = 0.935), and d = desired level of significance (.05). Substituting and adjusting for attrition rate at 20%, the sample size becomes 112. Simple random sampling was used for selection, targeting pregnant women in their second trimester at the antenatal clinic, AKTH, Kano.

Instruments

The instruments employed in the study included a validated semistructured questionnaire as well as plain and EDTA tubes for blood sample collection. Additionally, laboratory procedures used equipment such as a water bath (Thermo Fisher Scientific, TSGP28), centrifuge (MPW MED. Instruments, MPW-223e), spectrophotometer (20D; Techmel and Techmel), and microtiter plate along with a reader (DNM-9602, Wincom).

Data Collection

Demographic, Medical/Obstetrical, and Dietary Data Collection

A validated semistructured questionnaire containing 3 sections was administered to consenting pregnant women by interviewers so as to collect information on sociodemographic characteristics (including age, household size, education status, occupation, and monthly income) and medical/obstetrical history such as reported disease status, gravidity, parity, gestational age and birth spacing. A section also assessed the daily consumption of iron-rich food sources (heme iron–rich foods: red and organ meat, chicken, and fish; nonheme iron–rich foods: eggs, beans, spinach, and moringa), enhancers/potentiators (which are nutrients such as vitamin A and C that aid in improving the absorption of iron by the intestine and can be sourced from oranges and carrots), and inhibitors such as calcium and phytate, which prevent iron absorption and are available in coffee/tea.14, 15, 16

Blood Sample Collection

Four milliliters of blood sample were collected by a trained phlebotomist using venipuncture; immediately after, 1 mL of blood was transferred into an EDTA tube and 3 mL was transferred into a plain tube. The blood in the plain tube was allowed to clot and then centrifuged at 3000 rpm for 5 minutes to obtain serum and preserved at −20°C for further analyses.

Determination of Hemoglobin Concentration

The blood sample in the EDTA tube was used for the estimation of hemoglobin concentration based on the cyanmethemoglobin method. Twenty microliters of blood was added to 5 mL of Drabkin’s solution, and the absorbance was measured at 540 nm after 5 minutes of incubation at 25°C.¹⁷ The hemoglobin concentration was estimated with reference to the standard.

Determination of Serum Iron, Total Iron Binding Capacity, and Transferrin Saturation

Serum iron and total iron binding capacity (TIBC) were determined using commercial Centronic GmbH assay kits (Iron Feren S fluid kit IF01000060-4, and TIBC kit IF08000050) following the manufacturer’s instructions. Serum iron was determined using a colorimetric method according to Makino et al,¹⁸ where transferrin-bound iron is released at an acidic pH and reduced from ferric to ferrous ions. These ions react with ferrozine to form a violet colored complex. Fifty microliters each of sample, standard, and distilled water were added to 1000 µL of reagent (guanidine hydrochloride, pH 4.0-4.4) in separate tubes; the contents were mixed and incubated at 25°C for 10 minutes. The absorbance of the mixtures was measured at 560 nm, which was proportional to the serum iron concentration. Total iron binding capacity was estimated as described by Stookey¹⁹ and Yamanishi et al,²⁰ where serum was treated with an excess of ferrous ions to saturate the iron binding sites on transferrin. The excess ferrous ions were adsorbed and precipitated, and the iron content in the supernatant was measured to give the TIBC. Two hundred and fifty microliters of sample was added to 500 µL of FeCl₃, mixed, and allowed to stand for 30 minutes at 25°C. One spatula of magnesium carbonate was added to the mixture and kept for 60 minutes; the mixtures were shaken intermittently during the period and then centrifuged for 10 minutes at 4000 rpm. The clear supernatant was used for iron measurement as described by Makino et al.¹⁸ Transferrin saturation was calculated as:

$$\text{Transferrin}\text{saturation}(\%)=\frac{\text{Serum}\text{Iron}\text{Concentration}}{\text{TIBC}}\times 100$$

Determination of Serum Ferritin

Serum ferritin was determined using the Human Ferritin Enzyme Immunoassay Test Kit obtained from Pointe Scientific, INC. (USA) following the manufacturer’s protocol. The ferritin quantitative test was based on a microplate immunoenzymometric assay.²¹ To 25 µL each of sample and serum reference in microtiter wells, 100 µL of ferritin biotin reagent (biotinylated monoclonal mouse immunoglobulin G) was added, swirled gently, and incubated for 30 minutes at 25°C. The contents of the microplate were discarded, and the plate was then washed using 350 µL of wash buffer; 100 µL of ferritin enzyme conjugate (horseradish peroxidase) was then added and incubated for 30 minutes at 25°C. The contents were further discarded, the plate was washed, and 100 µL of substrate solution (tetramethylbenzidine and hydrogen peroxide in buffer) was added and incubated at 25°C for 15 minutes. Fifty microliters of stop solution (1 N hydrochloric acid) was finally added and mixed gently for 20 minutes. The absorbance was read at 450 nm in a microplate reader. Serum ferritin level was extrapolated from a ferritin standard curve.

Definitions of Anemia, ID, and IDA

Anemia was defined as hemoglobin levels less than 11.0 g/dL²²; ID was defined as serum ferritin less than 12 ng/mL²³ and transferrin saturation less than 14.0% and 9.0%^16,24 for second and third trimesters, respectively; IDA was defined as serum ferritin less than 12 ng/mL and hemoglobin levels less than 11.0 g/dL.²³

Data Analysis

Data collected were analyzed using SPSS software version 21 (IBM). Data on sociodemographics, medical/obstetrical history, dietary pattern, and prevalence of anemia, ID, and IDA were represented as percentages (%), whereas the levels of iron indices (hemoglobin, serum iron, TIBC, transferrin saturation, and serum ferritin) were presented as mean ± SD. Descriptive statistics were measured to summarize demographic data, medical/obstetrical data, and daily food consumption pattern. Independent sample t test was conducted for comparison of iron indices (among the 2 groups of pregnant women), except for TIBC, which was compared with the Mann-Whitney U test. Phi and Cramer’s V test was conducted to establish the association between sociodemographics/medical history and prevalence of anemia, ID, and IDA, while Eta-squared test was conducted to establish the association between dietary pattern and iron indices. P value ≤.05 was considered statistically significant.

Results

Sociodemographic Characteristics and Medical/Obstetrical History of Pregnant Women Attending the Antenatal Clinic, AKTH, Kano

The sociodemographic characteristics revealed that majority (49.1%) of the pregnant women were within the age of 19 to 28 years, with 59.9% having ≤5 people in their household and 58.0% having a tertiary education (Table 1). In terms of household monthly income, 42.9% earned ₦30 000 to ₦49 999, equivalent to USD $79 to $131, as indicated in Table 1. The medical history of the pregnant women showed that 87.5% had not been diagnosed with any disease at the time of data collection. Among the pregnant women, 49.1% were currently on supplements, with 56.4% taking an iron/folate supplement (Table 1). Obstetrical data showed that majority of the women (83.0%) were pregnant more than once, 45.5% had given birth 2 to 4 times, and 41.1% had experienced miscarriage or abortion (Table 1). Most of the pregnant women (38.4%) were within the gestational age of 19 to 22 weeks, while 32.1% practiced 12 to 24 months of birth spacing (Table 1).

Table 1.

Sociodemographic Characteristics and Medical/Obstetrical History of Pregnant Women Attending the Antenatal Clinic, Aminu Kano Teaching Hospital, Kano

Sociodemographic Characteristics	Percentage (%) n = 112	Medical/Obstetrical Data	Percentage (%) n = 112
Age		Disease status
19-28 y	49.1	Yes	12.5
29-38 y	42.9	No	87.5
39-48 y	8.0
No. of people in household		Disease type
≤5	59.9	Ulcer	7.1
6-10	33.0	Asthma	2.7
11-15	5.3	Others	2.7
>16	1.8
Level of education		Supplement intake
Nonformal	2.7	Yes	49.1
Primary	2.7	No	50.9
Junior secondary	3.6
Senior secondary	33.0
Tertiary	58.0
No. of children		Type of supplementa
None	25.0	Iron/folate	56.4
1-4	58.9	Multivitamin	30.9
5-8	16.1	Calcium	7.3
		Others	5.4
Occupation		Gravidity
Full housewife	50.0	Primigravida	17.0
Artisan/skilled worker	12.5	Multigravida	83.0
Civil servant	18.8
Others	18.8
Household monthly incomeb		Parity
<₦10 000	4.5	Nulliparous	20.5
₦10 000-₦29 999	12.5	Primiparous	11.6
₦30 000-₦49 999	42.9	Multiparous	45.5
≥₦50 000	40.2	Grand multiparous	22.3
		Gestational age
		14-18 wk	34.8
		19-22 wk	38.4
		23-26 wk	26.8
		Miscarriage/abortion
		Yes	41.1
		No	58.9
		Birth spacing
		Not applicable	24.1
		<12 mo	2.7
		12-24 mo	32.1
		>24 mo	41.1

^bSample size is 55, which comprises pregnant women taking a drug/supplementation.

^a₦1 is equivalent to USD $0.0026.

Daily Consumption Pattern of Some Iron-Rich Foods Among Pregnant Women Attending the Antenatal Clinic, AKTH, Kano

The daily consumption of heme and nonheme iron food sources, as well as enhancers and inhibitors of iron absorption14, 15, 16 among pregnant women, is presented in Figure 1A-C. The proportion of pregnant women who consumed heme iron food sources at least 1 to 3 times daily was, on average, 24.8%; approximately 72.3% did not have a daily intake of at least 1 iron-rich food source (Fig 1A). The proportion of pregnant women who did not consume at least 1 nonheme iron food source in the previous day was 64.8%; however, 37.2% consumed at least 1 nonheme iron food source the previous day, as shown in Figure 1B. In terms of enhancers and inhibitors of iron absorption, 25.3% of the pregnant women had an average daily consumption of enhancers, whereas 36.6% of the pregnant women consumed coffee/tea (inhibitor) at least 1 to 3 times daily (Fig 1C).

Fig 1.

Daily consumption pattern of heme iron–rich foods (A), nonheme iron–rich foods (B), and enhancers/inhibitors of iron absorption (C) among pregnant women attending the antenatal clinic, Aminu Kano Teaching Hospital, Kano. Values are expressed as percentages of pregnant women consuming iron-rich foods, potentiators/enhancers (orange, lettuce, carrot, and sweet potato), and inhibitors (coffee/tea) of iron absorption.14, 15, 16

Iron Indices of Iron/Folate Supplements in Compliant and Noncompliant Pregnant Women Attending the Antenatal Clinic, AKTH, Kano

The results indicated that iron/folate supplement-compliant pregnant women had significantly (P < .01) higher mean values of hemoglobin, serum iron, and transferrin saturation than noncompliant pregnant women in both trimesters. However, significantly (P < .01) lower levels of TIBC were observed among the compliant pregnant women compared with the noncompliant ones in both trimesters, as presented in Table 2. The prevalence of anemia among iron/folate supplement-compliant pregnant women was 14.6% while that of noncompliant pregnant women was 54.7% in the second trimester (Table 3). None of the compliant pregnant women was iron-deficient or had IDA in the second trimester, whereas 25.0% of the noncompliant pregnant women were iron-deficient and 17.5% had IDA in the second trimester, as presented in Table 3. In the third trimester, the prevalence of anemia among the compliant pregnant women was 45.0%, ID was 15.0%, and IDA was 5.0%, whereas among the noncompliant pregnant women, 84.4% were anemic, 31.1% were iron-deficient, and 26.7% had IDA, as indicated in Table 3.

Table 2.

Iron Indices of Iron/Folate Supplements in Compliant and Noncompliant Pregnant Women Attending the Antenatal Clinic, Aminu Kano Teaching Hospital, Kano

Trimester	Iron Indices	Iron/Folate Supplements		P Value
		Compliant	Noncompliant
Second trimester	Hemoglobin (g/dL)	13.3 ± 1.8a	10.8 ± 2.8b	.001
	Serum iron (µmol/L)	21.4 ± 5.0a	17.7 ± 6.6b	.002
	Total iron binding capacity (µmol/L)c	76.0 ± 18.1a	83.8 ± 13.4b	.002
	Transferrin saturation (%)	29.4 ± 9.2a	22.1 ± 9.8b	.001
	Serum ferritin (ng/mL)	33.0 ± 8.2a	29.7 ± 14.2a	.206
Third trimester	Hemoglobin (g/dl)	11.0 ± 1.9a	9.0 ± 2.2b	.001
	Serum iron (µmol/L)	15.1 ± 4.8a	12.0 ± 5.8b	.010
	Total iron binding capacity (µmol/L)c	108.3 ± 20.6a	119.6 ± 14.8b	.005
	Transferrin saturation (%)	14.4 ± 5.5a	10.2 ± 5.2b	.001
	Serum ferritin (ng/mL)	21.7 ± 8.2a	19.6 ± 9.9a	.291

Values are expressed as mean ± SD (n = 40 and n = 45 for iron/folate supplement-compliant and noncompliant pregnant women, respectively). Values bearing different superscript alphabets for the iron indices across the respective rows are significantly different.

^cAn independent sample t test and Mann-Whitney U test were conducted for iron indices.

Table 3.

Prevalence of Anemia, Iron Deficiency, and Iron Deficiency Anemia Among Iron/Folate Supplement-Compliant and Noncompliant Pregnant Women Attending the Antenatal Clinic, Aminu Kano Teaching Hospital, Kano

Trimester	Prevalence	Iron/Folate Supplements		Total (%)
		Compliant (%)	Noncompliant (%)
Second trimester (n = 112)	Anemia	14.6	54.7	37.5
	Iron deficiency	0.0	25.0	14.3
	IDA	0.0	17.5	10.7
Third trimester (n = 85)	Anemia	45.0	84.4	65.9
	Iron deficiency	15.0	31.1	23.5
	IDA	5.0	26.7	16.5

Values are presented as percentages of pregnant women (n = 48 and n = 64 for iron/folate supplement-compliant and noncompliant pregnant women, respectively, in the second trimester; n = 40 and n = 45 for iron/folate supplement-compliant and noncompliant pregnant women, respectively, in the third trimester). Indices used as criteria were as follows: anemia based on hemoglobin < 11.0 g/dL²²; iron deficiency based on serum ferritin < 12 ng/mL,²³ and transferrin saturation < 14.0% and <9.0%^16,24 for the second and third trimester, respectively; IDA based on serum ferritin <12 ng/mL and hemoglobin <11.0 g/dL.²³

IDA, iron deficiency anemia.

Factors Associated With the Prevalence of Anemia, ID, and IDA Among Pregnant Women Attending the Antenatal Clinic, AKTH, Kano

The result indicated that level of education had a weak, positive, and significant (0.270, P = .04) association with anemia status and household monthly income (0.222, P = .05), as presented in Table 4. Supplement intake showed a medium, negative, and significant association with anemia (−0.461, P = .03), ID (−0.309, P = .02), and IDA (−0.393, P = .04) (Table 4). Birth spacing was weakly, negatively, and significantly (P < .05) associated with anemia (−0.213, P = .01) and ID (−0.143, P = .04), as indicated in Table 4. However, gravidity, parity, and miscarriage/abortion were insignificantly (P > .05) and positively associated with anemia, ID, and IDA status (Table 4).

Table 4.

Factors Associated With Anemia, Iron Deficiency, and Iron Deficiency Anemia Status Among Pregnant Women Attending the Antenatal Clinic, Aminu Kano Teaching Hospital, Kano

Associated Factors	Anemia				Iron Deficiency				IDA
	Yes (%)	No (%)	Cramer’s Va	P Value	Yes (%)	No (%)	Cramer’s Va	P Value	Yes (%)	No (%)	Cramer’s Va	P Value
Level of education
Nonformal  Primary  Junior secondary  Senior secondary  Tertiary	2 (66.7) 1 (33.3) 1 (25.0) 17 (45.9) 21 (32.3)	1 (33.3) 2 (66.7) 3 (75.0) 20 (54.1) 44 (67.7)	0.270	.04b	0 (0.0) 0 (0.0) 0 (0.0) 5 (13.5) 11 (16.9)	3 (100) 3 (100) 4 (100) 32 (86.5) 54 (83.1)	0.135	.07	0 (0.0) 0 (0.0) 0 (0.0) 6 (16.2) 6 (9.2)	3 (100) 3 (100) 4 (100) 31 (83.8) 59 (90.8)	0.101	.08
HH monthly income
<₦50 000  ≥₦50 000	27 (40.3) 15 (33.3)	40 (59.7) 30 (66.7)	0.222	.05b	10 (14.9) 6 (13.3)	57 (85.1) 39 (80.0)	0.121	.09	7 (10.4) 5 (11.1)	60 (89.6) 40 (88.9)	0.136	.12
Supplement intake
Yes  No	10 (18.2) 32 (56.1)	45 (81.8) 25 (43.9)	−0.461	.03b	4 (7.3) 12 (21.1)	51 (92.7) 45 (78.9)	−0.309	.02b	3 (5.5) 9 (15.8)	52 (94.5) 48 (84.2)	−0.393	.04b
Miscarriage/abortion
Yes  No	26 (56.5) 16 (24.2)	20 (43.5) 50 (75.8)	0.147	.62	10 (21.7) 6 (9.1)	36 (78.3) 60 (90.9)	0.130	.46	8 (17.4) 4 (6.1)	38 (82.6) 62 (93.9)	0.170	.47
Birth spacing
Not applicable  <12 mo  12-24 mo  >24 mo	11 (40.7) 3 (100) 20 (55.6) 8 (17.4)	16 (59.3) 0 (0.0) 16 (44.4) 38 (82.6)	−0.213	.01b	5 (18.5) 1 (33.3) 8 (22.2) 2 (4.3)	22 (81.5) 2 (66.7) 28 (77.8) 44 (95.7)	−0.143	.04b	4 (14.8) 1 (33.3) 6 (16.7) 1 (2.2)	23 (85.2) 2 (66.7) 30 (83.3) 45 (97.8)	−0.107	.09
Gravidity
Primigravida  Multigravida	6 (31.6) 36 (38.7)	13 (68.4) 57 (61.3)	0.106	.26	2 (10.5) 14 (15.1)	17 (89.5) 79 (84.9)	0.118	.21	1 (5.3) 11 (11.8)	18 (94.7) 82 (88.2)	0.036	.40
Parity
Nulliparous  Primiparous  Multiparous	2 (8.7) 5 (38.5) 35 (46.1)	21 (91.3) 8 (61.5) 41 (53.9)	0.074	.13	1 (4.3) 2 (15.4) 13 (17.1)	22 (95.7) 11 (84.6) 63 (82.9)	0.117	.09	0 (0.0) 2 (15.4) 10 (13.2)	23 (100) 11 (84.6) 66 (86.8)	0.017	.38

Values are proportions of the pregnant women, N = 112.

HH, household; IDA, iron deficiency anemia.

^aPhi and Cramer’s V test.

^bValues are significantly (P ≤ .05) associated.

Association Between Iron Indices and Daily Consumption Pattern of Iron-Rich Foods Among Pregnant Women Attending the Antenatal Clinic, AKTH, Kano

The association between iron indices and consumption pattern of iron-rich foods was established using Eta test, as presented in Table 5. There was a small association/effect (Eta test = 0.02-0.12) between the consumption pattern of iron-rich foods and iron indices. Specifically, fish showed a small association (average Eta test = 0.05, 0.09, and 0.03) with hemoglobin, TIBC, and transferrin saturation, respectively, while beans showed a small association (average Eta test = 0.02) with serum iron, transferrin saturation, and serum ferritin (Table 5). Also, eggs showed a small association (average Eta test = 0.02, 0.06, and 0.03) with hemoglobin, TIBC, and serum ferritin, respectively, as presented in Table 5.

Table 5.

Association Between Iron Indices and Daily Consumption Pattern of Iron-Rich Foods Among Pregnant Women Attending the Antenatal Clinic, Aminu Kano Teaching Hospital, Kano

Food	Iron Indices
	Hb	SI	TIBC	TS	SF
Red meat	0.01	0.00	0.01	0.01	0.00
Liver	0.01	0.01	0.01	0.00	0.01
Chicken	0.02a	0.00	0.01	0.00	0.00
Fish	0.05a	0.01	0.09a	0.03a	0.00
Egg	0.02a	0.01	0.06a	0.01	0.03a
Beans	0.04a	0.02a	0.00	0.02a	0.02a
Soybeans	0.01	0.00	0.01	0.01	0.00
Pumpkin	0.00	0.00	0.00	0.00	0.00
Spinach	0.01	0.01	0.01	0.01	0.02a
Moringa	0.00	0.01	0.01	0.01	0.01

Values are Eta-squared, showing association/effect size of nominal and interval variables on each other.

Hb, hemoglobin; SF, serum ferritin; SI, serum iron; TIBC, total iron binding capacity; TS, transferrin saturation.

^aValues with a small association/effect with the corresponding vertical and horizontal variable (Eta test: ≥0.26 = large association/effect; 0.13-0.25 = medium association/effect; 0.02-0.12 = small association/effect).

Discussion

In this study, IDA and its associated factors were investigated among pregnant women attending the antenatal clinic, AKTH, Kano. The study included 112 pregnant women in their second trimester, and 85 of them were followed up successfully to their third trimester. Among the pregnant women, 58.0% had a tertiary education, which should be a great advantage when it comes to seeking proper health care. The sociodemographic factors assessed have been reported to have significant effect on the condition and outcomes of pregnancy.¹³ This study reported that level of education and household monthly income were significantly associated with anemia status. Level of education, household monthly income, and cultural practices/differences, among others, may affect response and compliance to health and nutrition advice from health professionals. These factors may also affect health-seeking behavior and eating habits of pregnant women, which subsequently have an impact on pregnancy and its outcomes.

In the present study, 56.4% of the pregnant women reported that they took iron/folate supplements, while 30.9% took multivitamins. This study established a negative and significant association between supplement intake and anemia, ID, and IDA status. The practice of daily oral iron and folate supplementation among pregnant women in the study area requires improvement, and the health care workers should continue to encourage and inform pregnant women on the benefits of supplementation to both the mother and the growing fetus. Multiple pregnancies, short recovery between pregnancies, and multipara have been reported to be risk factors associated with anemia and ID during pregnancy.²⁵ This study also reported a negative and significant association between birth spacing and anemia, ID, and IDA status; however, an insignificant association was reported between gravidity and parity and anemia, ID, and IDA. Based on our results, the majority of pregnant women were multigravida and multiparous, which might predispose these pregnant women to the development of anemia and ID if preventive measures are not prioritized. The practice of birth spacing (WHO recommends at least a 24-month interval before attempting the next pregnancy) among pregnant women in AKTH is encouraging, as the majority wait beyond 24 months before attempting the next pregnancy, which was similar to the earlier report by Nwizu et al.¹³

One of the sustainable strategies for preventing IDA is to improve consumption of diversified foods and eating habits in order to enhance iron status and overall health.⁹ Daily consumption of heme and nonheme iron–rich foods among pregnant women was low, and the nonheme iron–rich foods were further challenged by low bioavailability. The leading cause of anemia among pregnant women in West Africa was reported to be inadequate intake of diets rich in iron.^26,27 Similarly, due to the increased requirement for iron during pregnancy, which cannot be met by a routine diet, consumption of heme and nonheme iron–rich foods¹⁶ is essential in order to meet the iron needs of the pregnant mother and the growing fetus. Apart from the availability of iron to the pregnant woman and the fetus by consuming iron-rich foods, they also contribute to energy (calories), vitamins (such as vitamins B9 and B12), and minerals (such as zinc and selenium) necessary for a healthy pregnancy. An avenue to overcome low bioavailability of iron from nonheme iron–rich foods is to consume these foods together with enhancers, such as vitamins A and C (from oranges, lettuce, spinach, and moringa), and avoid their consumption with any of the inhibitors, such as tannins in coffee/tea, as reported in Figure 1C.^15,16 There was moderate consumption of enhancers of iron absorption among the pregnant women (Fig 1C); therefore, there is a need for more awareness among pregnant women in AKTH about the benefits of enhancers of iron absorption, as well as the disadvantages of consuming iron-rich foods with inhibitors. The high consumption of coffee/tea (41%) recorded among the pregnant women (Fig 1C) may inhibit/limit the amount of iron absorbed by the body (which could lead to anemia and ID).

Anemia is a critical risk factor during pregnancy, which is associated with an increased occurrence of maternal and fetal morbidity and mortality.²⁸ The prevalence of anemia across the trimesters reported in this study was higher than the values of 14.9% and 37.0% (based on packed cell volume <30%) recorded in second and third trimesters, respectively, in a cross-sectional study conducted among pregnant women in Kano.¹³ Similarly, Gwarzo and Ugwa²⁹ found the prevalence of anemia (based on packed cell volume <30%) to be 24.5% among pregnant women based on their study at General Hospital, Dawakin Kudu, Kano. The high prevalence reported in this study could be associated with a high proportion of multigravida and multipara among the pregnant women studied, or possibly most of the pregnant women entered pregnancy with low iron stores. The high prevalence of anemia could also be attributed to the low consumption pattern of iron-rich foods among pregnant women, as observed in their dietary pattern (Fig 1); this can further be linked to the contribution of consumption pattern of iron-rich foods to iron indices estimated, as presented in Table 5. The daily consumption pattern of iron-rich foods among pregnant women contributed an average of 3.5% to the levels of iron indices estimated; however, the study acknowledges the fact that multiple analyses were used without statistical correction.

The prevalence of ID among pregnant women in this study was 14.3% and 23.5% during the second and third trimesters, respectively. The results of this study were similar to those obtained from pregnant women in Calabar, Cross-River State, who reported a 12.5% and 23.3% prevalence of ID (based on soluble transferrin receptor >2.4 µg/mL) in the second and third trimesters, respectively.³⁰ This prevalence observed may be associated with the low consumption pattern of iron-rich foods among the pregnant women, although majority of the pregnant women in the present study were taking supplements; this is further challenged by poor compliance. The prevalence of IDA among pregnant women was 10.7% and 16.5% in the second and third trimesters, respectively. The results obtained were somewhat similar to those of Okafor et al,³⁰ where they found a 12.5% and 20.0% prevalence of IDA in the second and third trimesters, respectively, among pregnant women in Calabar based on soluble transferrin receptor >2.4 µg/mL and hemoglobin < 11g/dL. Similarly, Erhabor et al³¹ reported a prevalence of 13.5% based on ferritin levels <12.0 ng/mL among pregnant women in Sokoto State; likewise, 12.3% prevalence of IDA based on serum ferritin <12.0 ng/Ml was found among pregnant women in Lagos State, Nigeria.³² The prevalence of IDA observed in this study could either be linked to the mother’s low iron stores at the time of conception or the quantity of iron absorbed as the gestation progresses.³³ It might also be due to low consumption patterns of iron-rich foods or infections, such as malaria and hookworm infestation.³⁴

The lower prevalence of anemia, ID, and IDA observed among the compliant pregnant women might be due to the intake of iron/folate supplements as well as consumption of iron-rich foods with enhancers of iron absorption. World Health Organization recommends daily oral iron and folic acid supplementation as part of antenatal care to reduce the risk of maternal anemia and ID.³⁵ A lack or poor intake of these supplements could be the reason for the high prevalence of anemia, ID, and IDA observed among the noncompliant pregnant women in this study; this could even be worsened by parasitic infections or multiple pregnancies and births, as well as low consumption of iron-rich foods reported among the pregnant women investigated. Furthermore, the higher values of the iron indices observed among the compliant pregnant women could be attributed to the iron/folate supplements they took, which have been reported to improve iron status and prevent anemia and ID.³⁵ Similarly, it was observed in this study that there was a decrease in iron indices investigated as pregnancy progressed, except for TIBC, which is the maximum iron concentration that can be bound by serum proteins (specifically transferrin), and its levels increased during ID and pregnancy. These changes might be due to the fact that iron requirements increase remarkably throughout the second trimester due to erythrocyte mass expansion and transfer of high levels of iron to the developing fetus and placenta.³⁶

Limitations

This study did not record whether coffee/tea (inhibitors of iron absorption) was consumed alongside nonheme iron food sources or otherwise. The study also acknowledges the fact that multiple analyses were used without statistical correction for the estimation of the contribution of iron-rich foods to iron levels among pregnant women in the study area. Assessment of other contributing factors or causes of anemia, such as malaria and hookworm infestation, was not conducted in this study.

Conclusions

The prevalence of anemia among the pregnant women studied was of public health significance. Pregnant women taking iron/folate supplements had higher iron indices than the noncompliant pregnant women. The prevalence of IDA among pregnant women was 10.7% and 16.5% in the second and third trimesters, respectively. This study observed that the consumption pattern of iron-rich foods among the pregnant women investigated was low and had little effect on the iron indices estimated, while supplement intake and birth spacing had a significant negative association with anemia, ID, and IDA. Pregnant women should be continuously encouraged to take an iron/folate supplement, as well as creating awareness of iron-rich foods, foods that enhance iron absorption, and good feeding practices in order to combat anemia, ID, and IDA.

Acknowledgments

The managements of Ahmadu Bello University, Zaria, Nigeria, and Aminu Kano Teaching Hospital, Kano, are duly acknowledged for providing facilities, ethical approval, support, and an avenue toward the realization of this study. We also acknowledge the Ministry of Health, Kano State, and the pregnant women who voluntarily participated in the research for their patience and cooperation throughout the duration of the study.

Funding Sources and Conflicts of Interest

No funding sources or conflicts of interest were reported for this study.

Contributorship Information

Muhammad Auwal Saliu, MSc, Aliyu Salihu, PhD, and Sanusi Bello Mada, PhD

Concept development (provided idea for the research): M.A.S., A.S., S.B.M.

Design (planned the methods to generate the results): M.A.S., A.S., S.B.M.

Supervision (oversight, organization and implementation): A.S., S.B.M.

Data collection/processing (experiments, organization, or reporting data): M.A.S.

Analysis/interpretation (analysis, evaluation, presentation of results): M.A.S., A.S., S.B.M.

Literature search (performed the literature search): M.A.S.

Writing (responsible for writing a substantive part of the manuscript): M.A.S.

Critical review (revised manuscript for intellectual content): A.S., S.B.M.

Data Availability

The research data of this study are available from the corresponding author after approval and reasonable request.

Practical Applications.

• •This study investigated IDA, its associated factors, and intake of iron/folate supplements among 112 pregnant women in the antenatal care facility of AKTH, Kano.
• •Among the pregnant women, 56.4% were iron/folate supplement-compliant, and 83.0% and 67.8% were multigravida and multipara, respectively.
• •Progression from the second to third trimesters was associated with increased risk of anemia, iron deficiency, and IDA among the pregnant women.
• •Pregnant women taking iron/folate supplements had higher iron indices than the noncompliant pregnant women.
• •Consumption of iron-rich foods among pregnant women was low and had little effect on the iron indices estimated, while supplement intake and birth spacing had a significant negative association with anemia, iron deficiency, and IDA.

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