Maternal packed cell volume, anemia severity, and placental hematologic lesions in HIV-positive and HIV-negative pregnancies: A comparative clinicopathologic study

INTRODUCTION

Anemia remains one of the most common and clinically consequential medical disorders complicating pregnancy, particularly in low- and middle-income countries, where it contributes substantially to maternal morbidity, adverse perinatal outcomes, and increased healthcare utilization.^[1-7] Packed cell volume (PCV), a practical surrogate for hematocrit, is routinely used in antenatal care to assess maternal hematologic status and guide clinical decision-making.^[4,8-11] Reduced PCV during pregnancy has been associated with impaired maternal functional capacity, increased susceptibility to infection, postpartum hemorrhage, preterm delivery, and low birth weight.^[2,4,8-15] However, PCV is often interpreted as a single, static measurement, despite its dynamic nature and susceptibility to physiologic plasma volume expansion, nutritional status, infection, and chronic disease across gestation.

Although anemia in pregnancy is commonly defined using hemoglobin thresholds (including trimester-specific cutoffs), PCV/hematocrit remains a widely used and clinically meaningful screening index in routine antenatal practice, and clinical guidance provides hematocrit-based thresholds that parallel hemoglobin cutoffs.^[16-18] In many low-resource antenatal settings, serial PCV measurements are more consistently available than hemoglobin concentrations.^[16] Accordingly, this study leveraged routinely recorded antenatal PCV values to characterize sustained maternal hematologic status and anemia severity.

Evidence from longitudinal studies underscores the clinical importance of changes in maternal hemoglobin and PCV during pregnancy.^[9,14,15] A South African cohort study demonstrated a decline in anemia prevalence from early pregnancy to the third trimester, reflecting dynamic hematologic adaptation.^[14] Systematic reviews further indicate that maternal hemoglobin trajectories are associated with key perinatal outcomes, including reductions in low birth weight and stillbirths, alongside increased risks of hypertensive disorders.^[14,15] Importantly, a U-shaped relationship between hemoglobin concentration and pregnancy outcomes has been described, with both low and high levels conferring risk, although substantial population-level variability persists and warrants further investigation.^[9]

Pregnancy in women living with human immunodeficiency virus (HIV) presents additional and complex hematologic challenges.^[1-3,12] HIV infection is independently associated with anemia through multiple mechanisms, including chronic inflammation, bone marrow suppression, opportunistic infections, nutritional deficiencies, and antiretroviral therapy-related effects.^[1] Studies have reported a high prevalence of anemia among pregnant women with HIV, particularly in those with low CD4 counts and high viral loads, and anemia is most common in advanced stages of HIV disease.^[3,12] Despite this, data examining anemia severity and sustained hematologic status in pregnancy, especially using averaged hematologic indices rather than isolated measurements, remain limited. Moreover, the relative contributions of maternal age, parity, and nutritional status to anemia risk in HIV-positive pregnancies are not well defined.^[2]

Beyond maternal systemic effects, maternal hematologic status may influence placental structure and function.^[19-26] Placental hematologic lesions, including retroplacental hematomas, intervillous thrombo-hematomas, and adherent blood clots, are of particular interest to perinatal pathologists, as they may reflect underlying maternal vascular, hematologic, or inflammatory disturbances.^[19-26] Placental vascular lesions are recognized contributors to fetal injury, and specific intraplacental hematomas have been linked to maternal vascular disease.^[23,27] However, the relationship between maternal hematologic parameters and placental hematologic lesions remains inconsistent, with some studies demonstrating complex, indirect associations rather than reliable predictive relationships.^[24]

In this context, this study aimed to conduct a comparative clinicopathologic evaluation of HIV-positive and HIV-negative pregnancies. The objectives were to analyze subject-level average PCV, characterize anemia prevalence and severity, assess associations with HIV disease stage, and evaluate placental hematologic features. These objectives inform antenatal surveillance and integrated obstetric– pathologic care in settings with a high burden of HIV-related anemia.

MATERIAL AND METHODS

RESULTS

Comparison of mean PCV by HIV status

The mean PCV was significantly lower among HIV-positive mothers compared with HIV-negative mothers (31.9% ± 4.8 vs. 33.7% ± 3.9; Mann–Whitney U P ≈ 0.02) [Table 1]. PCV distributions were non-normal in both groups.

Figure 1a illustrates the distribution of mean PCV by HIV status, demonstrating a leftward shift among HIV-positive mothers.

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Figure 1: (a) Distribution of mean packed cell volume (PCV) by human immunodeficiency virus (HIV) status. Box-and-whisker plots showing the distribution of subject-level mean PCV among HIV-negative and HIV-positive mothers. The boxes represent the interquartile range, the horizontal line indicates the median, and the whiskers denote the range of values. Mean PCV was calculated for each subject using all available antenatal PCV measurements. (b) Anemia severity stratified by HIV status. Stacked bar chart illustrating the distribution of anemia severity categories (not anemic, mild, moderate, and severe anemia) among HIV-negative and HIV-positive mothers, based on subject-level mean PCV. Bar segments represent the number of mothers in each anemia category.

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Relationship between PCV and nutritional status

Nutritional status was significantly associated with mean PCV (Kruskal–Wallis P ≈ 0.009). Obese mothers had the highest mean PCV, while normal-weight and overweight mothers had lower values [Table 2]. Anemia prevalence also differed significantly by nutritional status (χ², P ≈ 0.002), with anemia observed only among normal-weight and overweight mothers and absent among obese mothers. Figure 2a illustrates the mean PCV by nutritional category.

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Figure 2: (a) Mean packed cell volume (PCV) by nutritional status. Box-and-whisker plots depicting the distribution of subject-level mean PCV across nutritional status categories (normal weight, overweight, and obese). Boxes represent the interquartile range, with medians and ranges indicated. (b) Anemia severity across human immunodeficiency virus (HIV) disease stages. Stacked bar chart showing the distribution of anemia severity categories across HIV disease stages among HIV-positive mothers. Anemia severity was determined using subject-level mean PCV, and bars represent the number of mothers in each severity category within each HIV stage.

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Relationship between PCV and placental hematologic lesions

No significant associations were observed between mean PCV or anemia status and the presence of retroplacental hematoma, membrane hematoma, umbilical cord hematoma, chorionic plate hematoma, or intervillous thrombohematoma (all P > 0.20) [Table 3]. Similarly, adherent blood clot size was not associated with mean PCV (Kruskal–Wallis P = 0.67) or anemia prevalence (χ², P = 0.12) [Table 3]. Figure 3 summarizes the mean PCV by clot size category.

Table 3: Association of mean PCV and anemia with placental hematologic lesions and adherent blood clot size.

Association between mean PCV and placental hematologic lesions
Lesion		HIV-negative		HIV-positive		P-value‡
		Mean PCV (%)/lesion present	Mean PCV (%)/lesion absent	Mean PCV (%)/lesion present	Mean PCV (%)/lesion absent
Retroplacental hematoma		31.8	33.6	30.4	32.1	0.21
Membrane hematoma		33.9	33.4	32.6	31.9	0.90
Umbilical cord hematoma		34.0	33.5	32.0	31.8	0.90
Chorionic plate hematoma		33.7	33.4	32.1	31.8	0.90
Intervillous thrombo-hematoma		31.8	33.6	30.4	32.1	0.92
‡Mann–Whitney U test
Mean PCV and anemia by adherent blood clot size
Clot size (mL)	HIV-negative mean PCV±SD			HIV-positive mean PCV±SD		Anemia n (%)
<100	33.1±4.9			31.6±5.2		13 (17.8)
100–200	34.0±2.8			32.2±3.4		2 (4.0)
201–300	32.0±4.5			31.8±4.6		2 (20.0)
>300	32.0			—		0 (0.0)
Kruskal–Wallis P=0.67; Chi-square P=0.12. PCV: Packed cell volume, HIV: Human immunodeficiency virus, SD: Standard deviation

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Figure 3: Mean packed cell volume (PCV) according to adherent blood clot size. Box-and-whisker plots demonstrating the distribution of subject-level mean PCV according to categories of adherent placental blood clot size (<100 mL, 100–200 mL, 201– 300 mL, and >300 mL). Boxes indicate the interquartile range, with medians and ranges shown.

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DISCUSSION

This study provides a comprehensive clinicopathologic evaluation of maternal PCV, anemia severity, and placental hematologic features in HIV-positive and HIV-negative pregnancies, using subject-level average PCV derived from multiple antenatal measurements. By integrating maternal age, nutritional status, HIV disease stage, and systematic placental hematological pathology assessment, the study offers a nuanced appraisal of sustained hematologic status in pregnancy and its clinical and pathological correlates.

The absence of significant differences in ABO blood group, Rhesus status, and genotype distributions between HIV-positive and HIV-negative mothers suggests that inherited hematologic traits did not confound the observed associations between HIV status and maternal PCV or anemia in this cohort. This finding is consistent with Okorie et al.^[31] and Ukaejiofo and Nubila’s^[32] reports, which demonstrated minimal or inconsistent associations between blood group antigens and HIV infection. Notably, a recent systematic review and meta-analysis failed to establish reproducible, clinically meaningful associations between blood group AB and HIV infection risk, but highlighted heterogeneity across regions and study designs, supporting cautious interpretation.^[33] In contrast, Nneli et al., and Davison et al., reported subtle variations in blood group frequencies in their study populations.^[34,35] Importantly, our study was not designed or powered to evaluate ABO–HIV susceptibility (AB counts were limited), and we therefore treat ABO findings as descriptive and hypothesis generating. Larger prospective cohorts could incorporate ABO and other host factors as exploratory endpoints alongside virologic, treatment, and inflammatory covariates. Collectively, these data support the interpretation that HIV-associated anemia in pregnancy is predominantly driven by acquired rather than inherited hematologic factors.

HIV-positive mothers exhibited significantly lower mean PCV compared with HIV-negative mothers. The use of averaged PCV across multiple antenatal measurements strengthens this observation by minimizing the influence of transient physiologic fluctuations and intercurrent illness. This finding aligns with prior studies by Adesina et al., Ekwempu et al., and Abdulqadir et al., from Nigeria and other sub-Saharan African settings, demonstrating consistently lower hematocrit or PCV values among HIV-positive pregnant women.^[11,13,36] Semba et al., in their study, mechanistically showed that HIV-associated anemia reflects the combined effects of chronic inflammation, impaired erythropoiesis, nutritional deficiencies, opportunistic infections, and antiretroviral therapy-related toxicity.^[1] The present findings reinforce HIV infection as a persistent determinant of reduced hematologic reserve during pregnancy.

Anemia was significantly more prevalent and more severe among HIV-positive mothers, with mild anemia occurring almost exclusively in this group and moderate-to-severe anemia also being more frequent. A similar pattern has been documented in a previous study by Eze et al., which showed consistently higher anemia prevalence among HIV- positive pregnant women compared with HIV-negative controls.^[4] Importantly, O’Brien et al. showed in their study that anemia severity carries prognostic significance, as moderate and severe anemia were independently associated with increased mortality and accelerated disease progression in HIV-infected populations.^[6] These findings underscore the clinical value of severity-based anemia classification in antenatal care, particularly in HIV-endemic settings.

Parity was not independently associated with mean PCV in this study, suggesting that reproductive history alone does not substantially influence sustained maternal hematologic status when HIV-related factors are considered. While a study by Adesina et al. reported a higher anemia risk among primigravid HIV-positive women, another study by Sharief and Masyarakat similarly found no consistent association between parity and hemoglobin levels.^[10,13] In contrast, nutritional status demonstrated a significant association with mean PCV, with obese mothers exhibiting higher PCV values. This observation likely reflects complex physiologic and metabolic influences on plasma volume expansion and red cell concentration rather than superior hematinic status, a distinction that has been emphasized in prior nutritional and hematologic studies by Sharief and Masyarakat.^[10]

Among HIV-positive mothers, advancing HIV disease stage was strongly associated with declining mean PCV and increasing anemia severity. This stage-dependent gradient represents one of the most clinically salient findings of the study and is consistent with studies by Levine et al., and Nandlal et al., who linked low CD4 counts and advanced disease to anemia.^[7,12] Large cohort and systematic reviews have demonstrated that anemia prevalence increases markedly with HIV disease progression, although reported prevalence ranges widely across populations.^[5,7,37] The present findings reinforce the importance of HIV disease staging as a key determinant of hematologic vulnerability during pregnancy. In addition, hemoglobin concentrations and gestational age at the time of each antenatal hematologic measurement were not consistently captured, precluding trimester-specific anemia classification and limiting direct comparability with hemoglobin-based guideline definitions.

No significant associations were observed between maternal PCV or anemia severity and placental hematologic lesions or adherent blood clot size. These findings suggest that placental hematologic pathology reflects multifactorial local and systemic processes that are not adequately captured by maternal PCV alone. Prior placental pathology studies by Rayne and Kraus, Redline and Litt and Hecht, have emphasized the complexity of these lesions, implicating maternal vascular perfusion, inflammatory pathways, and fetal vascular factors rather than isolated maternal hematologic indices.^[20,23,24] Although studies by D’Costa et al. and Izuka et al. showed that HIV infection was associated with increased placental pathology, including inflammatory and vascular lesions, the present results indicate that maternal PCV is not a reliable surrogate marker for predicting specific placental hematologic lesions.^[19,26]

Overall, the key strengths of this study include the use of subject-level averaged PCV, systematic anemia severity classification, and integrated placental hematological pathologic assessment. Clinically, the findings support intensified anemia surveillance and management in HIV-positive pregnancies, particularly among women with advanced disease. From a perinatal pathology perspective, the results caution against reliance on maternal PCV as a proxy for placental hematologic pathology, underscoring the need for direct placental examination.

This study has several limitations that should be considered when interpreting the findings. First, its observational design precludes causal inference, and residual confounding by unmeasured variables, such as iron status, inflammatory markers, and antiretroviral therapy regimens, cannot be excluded. Second, genotype data were incomplete, limiting the ability to fully assess inherited hematologic contributions. Third, some subgroup analyses, particularly those involving advanced HIV disease stages and grand multiparity, were constrained by small sample sizes, reducing statistical power and precision. Regarding the choice of hematologic index, we acknowledge that contemporary global guidance primarily defines anemia in pregnancy using hemoglobin concentrations with trimester-specific cutoffs. However, hematocrit/PCV remains clinically actionable in many antenatal programs, and clinical guidance provides hematocrit thresholds that parallel hemoglobin-based screening.^[16-18,29] In our retrospective dataset, hemoglobin values and gestational age at each PCV sampling point were not consistently available; consequently, trimester-stratified anemia prevalence could not be estimated. To reduce the influence of transient physiologic variation across gestation, we analyzed subject-level mean PCV using all available antenatal measurements, and we selected PCV <30% as a conservative primary definition of clinically meaningful anemia. We further provided a sensitivity analysis using PCV <33% to facilitate comparison with guideline-based screening thresholds. Finally, although placental hematologic lesions were systematically assessed, their multifactorial etiology may not be adequately captured by maternal PCV alone, potentially obscuring subtle associations.

CONCLUSION

In this comparative clinicopathologic study, HIV infection in pregnancy was associated with significantly lower mean PCV and a higher prevalence and severity of anemia, particularly among women with advanced HIV disease. Nutritional status influenced maternal PCV, whereas parity and age were not independent determinants of sustained hematologic status. Maternal PCV and anemia severity were not reliably associated with placental hematologic lesions or adherent blood clot size, underscoring the complexity of placental pathology. These findings highlight the importance of stage-stratified anemia surveillance and management in HIV-positive pregnancies and caution against reliance on maternal PCV as a surrogate marker for placental hematologic pathology.