European Journal of Cardiovascular Medicine

Feto-maternal haemorrhage (FMH) refers to the passage of fetal erythrocytes into the maternal circulation, a phenomenon that can occur spontaneously or as a result of obstetric interventions.¹ FMH is a critical clinical event due to its potential to cause severe fetal anemia, alloimmunization in Rh-negative mothers, and in extreme cases, fetal death.² The incidence of FMH varies widely, with studies reporting rates ranging from 3% to 30% depending on the population studied and the detection methods used.³

During the third trimester of pregnancy, the risk of FMH increases due to physiological changes in the placenta and the growing fetal size.⁴ The immediate postpartum period is another high-risk phase, as uterine contractions and placental separation can exacerbate fetal blood loss into the maternal circulation.⁵ Despite its clinical significance, FMH often goes undetected due to the lack of routine screening protocols and the asymptomatic nature of mild cases.⁶

The Kleihauer-Betke (KB) test and flow cytometry are the most commonly used methods for detecting FMH. The KB test, although widely available, has limitations in sensitivity and specificity, while flow cytometry offers greater accuracy but is less accessible in resource-limited settings.⁷ Understanding the incidence, volume, and risk factors associated with FMH is essential for developing effective screening and management strategies.

This study aims to evaluate the incidence and volume of FMH during the third trimester and immediate postpartum period in a sample size of 90 women, identify associated risk factors, and assess the clinical implications for both mother and fetus. By addressing these objectives, we hope to contribute to the growing body of knowledge on FMH and inform clinical practice.

 prospective observational study was conducted over 12 months at a tertiary care hospital. The study population included 90 pregnant women in their third trimester (28–40 weeks) and the immediate postpartum period (within 24 hours of delivery).

Inclusion Criteria:

1. Singleton pregnancy.
2. Gestational age ≥ 28 weeks.
3. No known placental abnormalities (e.g., placenta previa, placental abruption).
4. Informed consent provided.

Exclusion Criteria:

1. Multiple pregnancies.
2. Placental abruption or preeclampsia.
3. History of recent trauma or invasive procedures (e.g., amniocentesis).
4. Refusal to participate.

Detection Methods:

1. Kleihauer-Betke (KB) Test: Maternal blood samples were collected and analyzed for the presence of fetal hemoglobin using acid elution techniques.
2. Flow Cytometry: A subset of samples was analyzed using flow cytometry for quantitative assessment of fetal red blood cells.

Data Collection: Demographic data, obstetric history, and clinical outcomes were recorded. The volume of FMH was calculated based on the percentage of fetal cells detected in maternal blood.

Statistical Analysis: Data were analyzed using SPSS version 25. Descriptive statistics, chi-square tests, and logistic regression were used to assess associations between variables.

The results are summarized in five tables:

Table 1: Demographic Characteristics of Study Population (n=90)

Table 2: Incidence of FMH in the Third Trimester and Postpartum Period

Table 3: Volume of FMH

Table 4: Risk Factors Associated with FMH

Table 5: Clinical Outcomes

The findings of this study highlight the clinical significance of FMH, particularly in the immediate postpartum period. The higher incidence of FMH postpartum (16.7%) compared to the third trimester (11.1%) aligns with previous studies, which suggest that uterine contractions and placental separation during delivery increase the risk of fetal blood entering the maternal circulation.⁸ The mean volume of FMH was also significantly higher postpartum (14.8 mL) compared to the third trimester (4.2 mL), underscoring the need for vigilant monitoring during and after delivery.

Maternal age ≥35 years, multiparity, and cesarean delivery were identified as significant risk factors for FMH. Advanced maternal age and multiparity may contribute to placental insufficiency or structural changes that predispose to FMH.⁹ Cesarean delivery, particularly emergency procedures, may involve greater manipulation of the uterus and placenta, increasing the likelihood of fetal blood leakage.¹⁰

The clinical outcomes associated with FMH, such as fetal anemia and neonatal ICU admission, emphasize the importance of early detection and intervention. The KB test remains a valuable tool for FMH screening, but its limitations in sensitivity and specificity highlight the need for more accurate methods like flow cytometry, especially in high-risk cases.¹¹

This study has limitations, including its small sample size and single-center design, which may limit the generalizability of the findings. Future research should focus on larger, multicenter studies to validate these results and explore the role of routine FMH screening in improving maternal and fetal outcomes.

FMH is a clinically significant event with a higher incidence and volume in the immediate postpartum period. Risk factors such as advanced maternal age, multiparity, and cesarean delivery should be considered in clinical practice. Early detection and appropriate management are essential to prevent adverse outcomes. Further research is needed to establish standardized protocols for FMH screening and intervention.

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