Anaemia among Antenatal Women: Determinants and Pregnancy Outcomes from a Prospective Hospital-Based Cohort Study

Anaemia in pregnancy remains a major public health concern globally and continues to affect maternal and neonatal health, particularly in low- and middle-income countries. It is characterized by a reduced haemoglobin concentration, leading to impaired oxygen transport and adverse physiological consequences for both the mother and the developing foetus. The World Health Organization defines anaemia in pregnancy as a haemoglobin concentration below 11 g/dL and classifies it into mild, moderate, and severe categories based on severity. Despite sustained public health efforts, anaemia continues to affect a large proportion of antenatal women worldwide [1].Pregnancy is associated with increased nutritional and metabolic demands due to expansion of plasma volume, increased red blood cell mass, and foetal growth requirements. These physiological changes, coupled with inadequate dietary intake and poor micronutrient bioavailability, predispose pregnant women to anaemia, particularly during the second and third trimesters. Iron deficiency remains the most common cause; however, deficiencies of folate and vitamin B12, chronic inflammation, parasitic infections, repeated pregnancies, and underlying medical conditions also contribute to the development of anaemia during pregnancy [2].

Anaemia in pregnancy has been consistently linked to adverse maternal outcomes such as fatigue, reduced physical capacity, increased susceptibility to infections, preeclampsia, postpartum haemorrhage, and higher need for blood transfusion. Severe anaemia has also been associated with increased maternal mortality. From a foetal and neonatal perspective, maternal anaemia is associated with low birth weight, preterm delivery, intrauterine growth restriction, low Apgar scores, increased neonatal intensive care unit admissions, and perinatal mortality, thereby contributing to long-term health and developmental consequences [3].India continues to bear a disproportionately high burden of anaemia among pregnant women despite long-standing national initiatives such as iron–folic acid supplementation and the Anaemia Mukt Bharat programme. Recent national survey data indicate that more than half of pregnant women remain anaemic, with higher prevalence observed in rural and socioeconomically disadvantaged populations. Poor compliance with supplementation, inadequate nutritional counselling, and gaps in antenatal monitoring have been identified as major barriers to effective anaemia control [4].Although several studies have reported the prevalence of anaemia during pregnancy, many are cross-sectional and fail to capture the dynamic changes in haemoglobin status across different trimesters. In addition, limited data are available on the incidence of newly developed anaemia during pregnancy and its association with pregnancy outcomes under routine clinical care. Prospective hospital-based cohort studies are therefore essential to generate real-world evidence on the determinants and outcomes of anaemia in pregnancy and to support evidence-based antenatal care practices [5].In view of the persistent burden of anaemia, its multifactorial determinants, and its significant impact on maternal and neonatal outcomes, the present study was undertaken to evaluate anaemia among antenatal women attending a tertiary care hospital using a prospective hospital-based cohort design. The findings are expected to provide clinically relevant evidence to strengthen antenatal screening, improve therapeutic compliance, and inform integrated clinical and public health strategies aimed at reducing anaemia-related morbidity during pregnancy [6].

OBJECTIVES OF THE STUDY

Primary Objective

• To determine the prevalence and incidence of anaemia among antenatal women attending a tertiary care hospital over a six-month period.

Secondary Objectives

• To analyse the socio-demographic, nutritional, and clinical determinants associated with anaemia during pregnancy.
• To evaluate the impact of maternal anaemia on pregnancy outcomes, including selected maternal complications and foetal/neonatal outcomes.
• To assess the utilisation and effectiveness of existing antenatal anaemia prevention and management interventions, such as iron–folic acid supplementation and nutritional counselling, and to identify areas for improvement.

Materials and Methods

Study Design

A hospital-based prospective cohort study was conducted to evaluate the prevalence, incidence, and determinants of anaemia among pregnant women and to examine its association with pregnancy outcomes. The prospective design enabled longitudinal assessment of haemoglobin status and related clinical variables across different stages of pregnancy, allowing identification of both existing and newly developed anaemia under routine antenatal care conditions.

Study Period

The study was carried out over a six-month period, allowing enrolment of participants across all three trimesters of pregnancy and follow-up until later stages of gestation.

Study Setting

The study was conducted in the antenatal outpatient clinics and labour wards of a tertiary care teaching hospital affiliated with a pharmacy practice department. The hospital caters to a mixed urban and rural population and provides comprehensive antenatal services, including routine haemoglobin estimation, nutritional counselling, and iron–folic acid supplementation as part of standard maternal healthcare.

Study Population

The study population comprised pregnant women attending antenatal care services during the study period, irrespective of gestational age. Inclusion of women from the first, second, and third trimesters enabled trimester-wise estimation of anaemia prevalence, incidence, and progression.

Sample Size Determination

The sample size was calculated using Cochran’s formula for prevalence studies. Based on an expected anaemia prevalence of approximately 40%, a 95% confidence level (Z = 1.96), and a margin of error of 5%, the minimum required sample size was estimated. To ensure adequate statistical precision and account for potential loss to follow-up, a final sample size of approximately 400 participants was targeted.

Sampling Technique

A purposive consecutive sampling technique was employed. All eligible pregnant women attending antenatal clinics during the study period were approached consecutively and enrolled until the required sample size was achieved.

Eligibility Criteria

Inclusion Criteria

• Pregnant women aged 18–45 years
• Women in any trimester of pregnancy
• Singleton pregnancy
• Willingness to provide written informed consent

Exclusion Criteria

• Known chronic medical conditions affecting haemoglobin levels, including chronic kidney disease, diabetes mellitus, or cardiovascular disorders
• Active infections known to influence haemoglobin concentration, such as malaria, tuberculosis, or HIV/AIDS
• Use of medications affecting haematopoiesis, including chemotherapy or immunosuppressive agents
• History of recurrent pregnancy loss or known congenital anomalies likely to influence pregnancy outcomes

Data Collection Procedures

Data were collected using a structured and pre-validated case record form through participant interviews, clinical examination, and review of medical records. Information collected included sociodemographic characteristics, obstetric history, inter-pregnancy interval, dietary habits, supplement use, and relevant clinical details.

Haematological Assessment

Venous blood samples were collected under aseptic conditions by trained personnel. Haemoglobin concentration was measured using an automated haematology analyser as part of routine laboratory investigations. Anaemia was classified according to World Health Organization criteria as:

• Mild anaemia: 10.0–10.9 g/dL
• Moderate anaemia: 7.0–9.9 g/dL
• Severe anaemia: <7.0 g/dL

Haemoglobin estimation was performed at enrolment and reassessed during the second and third trimesters to evaluate changes in anaemia status over time.

Dietary Assessment

Dietary intake was assessed using a 24-hour dietary recall method supplemented by a food frequency questionnaire. Particular emphasis was placed on intake of iron-rich foods, folic acid sources, dietary inhibitors of iron absorption (such as phytates and tannins), and enhancers of iron absorption, including vitamin C-rich foods.

Anthropometric Measurements

Anthropometric parameters including body weight, height, body mass index (BMI), and mid-upper arm circumference (MUAC) were measured using standardized procedures and calibrated instruments to assess maternal nutritional status.

Socio-Demographic and Clinical Assessment

Information on age, educational status, socioeconomic status, obstetric history, parity, antenatal supplement intake, and lifestyle factors was collected through structured interviews. Socioeconomic status was assessed using standard classification criteria appropriate to the local population.

Biochemical Investigations

Where clinically indicated, biochemical investigations including serum ferritin, vitamin B12, folate, and C-reactive protein (CRP) levels were performed to aid in identifying the type of anaemia and to differentiate nutritional anaemia from anaemia associated with inflammation or chronic disease.

Follow-Up Assessments

Participants were followed during routine antenatal visits. Clinical status and haemoglobin levels were reassessed during subsequent trimesters to identify incident cases of anaemia and to monitor progression or improvement.

Statistical Analysis

Data were entered into Microsoft Excel and analysed using appropriate statistical software. Continuous variables were summarised as mean ± standard deviation, while categorical variables were expressed as frequencies and percentages. Prevalence and incidence rates of anaemia were calculated. Associations between anaemia and potential risk factors were assessed using logistic regression analysis. Kaplan–Meier survival analysis was employed to evaluate time-dependent development of anaemia. A p-value <0.05 was considered statistically significant.

Ethical Considerations

Ethical approval was obtained from the Institutional Ethics Committee prior to study initiation. Written informed consent was obtained from all participants. Confidentiality and anonymity of participant information were strictly maintained throughout the study.

Ethical Considerations

Ethical approval for the study was obtained from the Institutional Ethics Committee (IEC) prior to initiation. Written informed consent was obtained from all participants. Confidentiality and anonymity of participant information were strictly maintained throughout the study.

RESULTS

Baseline Characteristics of the Study Population

A total of 300 pregnant women were enrolled and prospectively followed during the study period. The mean maternal age was 24.61 ± 4.07 years, with the majority (84.3%) belonging to the 20–30-year reproductive age group. Multigravida women constituted 65.3% of the cohort, while 33.7% were primigravida. More than half of the participants (53.3%) had one or two previous live births, reflecting cumulative nutritional demands due to repeated pregnancies (Table 1)

Socioeconomic assessment revealed that 55.3% of women belonged to lower or upper-lower socioeconomic classes. Rural residents accounted for 57.7% of the study population. Although most women reported non-vegetarian dietary habits (97.3%), access to healthcare services was limited, with 77% reporting poor access.

Table 1. Baseline Sociodemographic and Obstetric Profile (n = 300)

Figure 1. Age-wise distribution of pregnant women.

Prevalence and Severity of Anaemia

Anaemia, defined as haemoglobin <11 g/dL as per World Health Organization criteria, was identified in 66.7% of the study population. Among the study population, 66.7% of pregnant women were anaemic, with mild anaemia accounting for 30.0%, followed by moderate anaemia (26.7%) and severe anaemia (10.0%). One-third of the women were non-anaemic (Figure 2).

Table 2. Severity of Anaemia among Pregnant Women

Figure 2. Pie chart depicting the severity of anaemia.

This pie chart depicts the distribution of anaemia severity among pregnant women. Approximately one-third of the participants were non-anaemic, while the remaining two-thirds had varying degrees of anaemia, with mild anaemia being the most common, followed by moderate and severe anaemia.

Trimester-wise Distribution of Anaemia

Anaemia persisted throughout pregnancy, with increasing severity observed in later trimesters. Moderate anaemia showed a notable rise during the second and third trimesters, indicating progressive iron depletion with advancing gestation (Table 3)

Table 3. Trimester-wise Severity of Anaemia

Figure 3. Stacked bar graph of anaemia severity across trimester

This bar graph illustrates the trimester-wise distribution of anaemia severity among pregnant women. Mild anaemia was the most prevalent form across all trimesters. The proportion of moderate anaemia increased during the third trimester, while severe anaemia was more frequently observed during the second trimester, indicating a critical period for progression of anaemia.

Incidence of New-Onset Anaemia

Among women who were non-anaemic at baseline, 34 new cases developed during follow-up, giving an overall incidence of 12.78%. The incidence was significantly higher in the second trimester (28.6%) compared to the third trimester (10.3%).

Table 4. Incidence of Anaemia during Pregnancy

Figure 4. Kaplan–Meier curve showing time to development of anaemia.

Figure 4 depicts the cumulative incidence of anaemia during pregnancy. The incidence of new-onset anaemia was highest during the second trimester (28.6%), followed by the third trimester (10.3%), with an overall cumulative incidence of 12.8% during pregnancy.

Determinants of Anaemia

Younger maternal age (≤20 years), short inter-pregnancy interval (<18 months), vegetarian diet, irregular iron–folic acid (IFA) intake, history of infections, and abnormal menstrual patterns were statistically significantly associated with anaemia (p < 0.05). Education level and socioeconomic status did not independently predict anaemia.

Table 5. Determinants of Anaemia

Types of Anaemia

Iron deficiency anaemia was the most prevalent subtype (40%), followed by megaloblastic anaemia (25%) and anaemia of chronic disease (15%).

Table 6. Distribution of Anaemia Types

Figure 5. Etiological distribution of anaemia among pregnant women

This figure depicts the etiological distribution of anaemia among the study population. Iron deficiency anaemia was the predominant subtype (40.0%), followed by megaloblastic anaemia (25.0%) and anaemia of chronic disease (15.0%). Hemoglobinopathies (6.7%) and thyroid-related anaemia (5.0%) accounted for smaller proportions, indicating the multifactorial etiology of anaemia in pregnancy.

Maternal and Neonatal Outcomes

Maternal complications increased significantly with anaemia severity, including preeclampsia, postpartum haemorrhage, blood transfusion requirement, and prolonged hospital stay. Neonatal outcomes such as low birth weight, preterm birth, NICU admissions, and perinatal mortality showed a dose-response relationship with maternal anaemia severity.

Table 7. Maternal and Neonatal Outcomes by Anaemia Severity

Figure 6. Trend of maternal and neonatal complications with anaemia severity.

Figure 6 shows the comparative distribution of key maternal and neonatal outcomes among non-anaemic and severely anaemic pregnant women. The frequency of postpartum haemorrhage, blood transfusion requirement, low birth weight, and NICU admission was markedly higher among women with severe anaemia compared with non-anaemic women, demonstrating a clear severity-dependent increase in adverse outcomes (p < 0.001).

Utilisation and effectiveness of antenatal anaemia prevention and management interventions

Utilisation of antenatal anaemia prevention and management strategies varied among the study population. Regular iron–folic acid supplementation, nutritional counselling, deworming therapy, and adequate antenatal follow-up were significantly associated with improved haemoglobin levels and reduced anaemia severity (Table 9).

Table 9. Utilisation and effectiveness of antenatal anaemia prevention and management interventions among antenatal women (n = 300)